Part – A Taxonomy

Introduction

The nematodes are a successful group of invertebrates placed at a low

level in the taxonomic hierarchy of the animal kingdom. They are the most

diverse phylum, and one of the most diverse of all animals. They have

successfully adapted to nearly every ecological habitat from marine to fresh

water, from the Polar regions to the tropics, as well as the highest to the lowest of

elevations. They are ubiquitous in freshwater, marine, and terrestrial

environments, where they often outnumber other animals in both individual and

species counts, and are found in the locations as diverse as Antarctica and

oceanic trenches. Some of them also can withstand complete dryness on the

surface of rocks. Their size too is extremely variable ranging from less than 100

µm (Greefiella minutum) to greater than 8 metres (Placentonema gigantissima).

The nematodes are the planets most abundant metazoa; of every five animals,

four are nematodes (Platt, 1994; Bongers & Ferris, 1999). They are particularly

abundant in marine, freshwater, and soil habitats. A square yard of woodland or

agricultural habitat may contain several million nematodes. The existence of

nematodes living in water, soil or in parasitizing the plants remained largely

unknown perhaps, because of their exceedingly small size, absence of any

colouration, mostly underground habitat and the difficulties encountered in their

isolation.

The phylum Nematoda is characterized by high species diversity. It has

been estimated that the total number of described and undescribed species might

be ranged from 0.1 to 100 million (May, 1988; Hammond, 1992;

Lambshead,1993; Coomans, 2000). The nematodes are not only numerically

    1 

 

abundant, but they are also very diverse in terms of species. Usually species

richness at a single site is high with an average of 20-60 species per soil sample.

In soil, the nematodes dominate in number as well as species over all

other soil inhabiting animals collectively and have occupied all possible habitats

representing a very wide range of biological diversity. Soil nematode

communities have the potential to provide insights into many soil processes and

functions as most nematodes are active in soil throughout the year (Ritz &

Trudgill, 1999). Nematodes can be used as bioindicators of soil health because

they are ubiquitous and have diverse feeding behaviours and life strategies

(Bongers & Bongers, 1998; Neher, 2001). They occupy several trophic grades

and a central position in the soil food web and play significant roles in biological

processes such as nitrogen cycling and plant growth patterns (Neher, 2001). Soil

nematodes stabilize soil ecosystems, promote substance cycling and energy flow

(Ingham et al., 1985). The ecological classification of terrestrial nematodes have

usually been based on feeding biology (trophic functions) and on life strategies;

colonizers versus persisters (Bongers, 1990). Yeates et al. (1993) classified the

terrestrial nematodes into eight trophic groups viz., plant feeding, hyphal feeding,

substrate ingestion, predation on animals, bacterial feeding, unicellular eukaryote

feeding, dispersal/infective stage of parasites and omnivorous. Free-living

nematodes promote decomposition of soil organic matter, mineralization of plant

nutrients and nutrient cycling, amend soil physico-chemical property and

improve soil fertility (Ferris et al., 2004). Some free living nematodes suppress

bacterial, fungal and nematode diseases (Khan & Kim, 2007).

    2 

 

All terrestrial ecosystems consist of aboveground and belowground

components that interact to influence community- and ecosystem-level processes.

Several recent studies have indicated that biotic interactions in soil can regulate

the structure and functioning of the above ground communities (Wardle et al.,

2004). Soil nematode communities can provide unique insights into many aspects

of soil processes; they can offer a holistic measure of the biotic and functional

status of soils (Ritz & Trudgill, 1999). They are good environmental indicators

because of their strong relationships with land management (Todd, 1996; Neher

and Campbell, 1994; Liang et al., 1999; Fiscus and Neher, 2002) and

aboveground vegetation (Ingham et al., 1985; Bongers and Bongers, 1998;

Bongers and Ferris, 1999; Yeates, 1999).

Measurement of meiofaunal diversity and abundance is an important but

time consuming process. Morphological identification of individual organisms to

named species is often not technically possible due to sheer abundance, small

size, and lack of expert knowledge of the groups encountered. This is especially

true of nematodes, whose diversity in soils and sediments remains essentially

unknown. Surveys of benthic sediments suggest that the total species number for

marine nematodes may exceed 1 million (Lambshead 1993; Lambshead 2001),

with only a few thousand described in the scientific literature (Malakhov 1994;

De Ley & Blaxter 2002). In terrestrial systems, nematode diversity appears to be

under-reported (Lawton et al., 1998), with, for example, only about 200 species

of soil nematodes being described from the British Isles (Boag & Yeates 1998).

The maximum number of nematode taxa described from a single soil site is 228

from a prairie in Kansas, USA (Orr & Dickerson 1966; Boag & Yeates 1998).

    3 

 

Nematodes are arguably the most numerous metazoans in the soil and aquatic

sediments (Lambshead, 2004), the extraordinary species diversity, paucity of

trained taxonomists, labour intensive work for traditional morphological

identification of soil fauna challenges the nematode taxonomy. To develop new

technology for identification, classification, genome relatedness and diversity, in

nematode genepools the technology to be developed will use molecular,

biosystematic, informatic and genetic tools. New approaches are coming in use to

aid species identifications within the context of a classical morphological system.

Currently a shift from the purely phenotypic to using a combination of both

phenotypic and molecular methods is observed (Powers et al., 1997; Powers,

2004). Also, the phylogenetic species concept has gained more support recently

(Adams, 1998, 2002) and ways to extend its theoretical appeal into practicality

have been evaluated (Nadler, 2002).

For years, morphological identification was the only method widely used

to identify nematodes. As our knowledge of nematodes of agronomical

importance increased, it became clear that morphology alone did not reveal the

complete picture of observed pathological differences between populations

within morphologically delimited species. As a result, new methods have been

looked for that can better predict observed pathological behaviors among

populations within species. Numerous molecular techniques have been developed

that are capable of identifying and quantifying nematodes at the species level and

below. Techniques such as isoenzyme pattern analysis, restriction fragment

length polymorphism (RFLP) analysis, random amplified polymorphic DNA

(RAPD) analysis, polymerase chain reaction (PCR), quantitative polymerase

    4 

 

chain reaction (qPCR), and sequencing of diagnostic rDNA regions have all been

used successfully to identify and quantify several agriculturally important plant-

parasitic nematodes. These methods have their own advantages and limitations.

Most of these methods have been widely used in the diagnostics of agriculturally

important nematodes. DNA sequences of marker genes, Denaturing Gradient Gel

Electrophoresis (DGGE) and the more recently developed method of

pyrosequencing are the three methods employed in biodiversity studies of

freeliving forms. Andre et al. (2002) highlighted the need for the development

and consistency of methods in soil faunal monitoring; commenting that molecular

techniques for community analysis are now widely used in soil microbiology and

have greatly expanded our knowledge of soil microbes. Molecular methods

provide an alternative to traditional morphological identification for routine

assessment of described species. Their application has enabled profiling of

environmental samples of soil microbial populations, overcoming the need to

culture and identify bacteria and fungi from complex mixtures (Amann et al.,

1995) and similarly may reduce the taxonomic expertise currently required to

characterise microfaunal communities.

Blaxter et al. (1998) produced the first molecular phylogenetic framework

of the phylum Nematoda. They constructed a database of small subunit (SSU)

sequences from 53 taxa, including 41 new sequences to construct a phylogenetic

tree of nematodes. Sequences were aligned with reference to a secondary-

structure model and on the basis of similarity. They recognise three major clades:

Clade I groups the vertebrate-parasitic order Trichocephalida with the insect-

parasitic Mermithida, plant-parasitic Dorylaimida and free-living Mononchida,

    5 

 

Clade II links the plant-parasitic Triplonchida with the free-living Enoplida &

Monhysterida and clade C+S groups Chromadorida and Secernentea. Within

Secernentea three major clades were identified (clades III, IV and V). Clade III

represents a grouping of vertebrate- and arthropod-parasitic taxa from the orders

Ascaridida, Spirurida, Oxyurida and Rhigonematida. Clade IV a ‘cephalobid’

clade, groups the plant-parasitic orders Tylenchida and Aphelenchida, the

vertebrate-parasitic genus Strongyloides and the entomopathogenic genus

Steinernema with free-living bacteriovores of the rhabditid families Cephalobidae

and Panagrolaimidae. Clade V groups C. elegans and other members of the

suborder Rhabditina with the vertebrate-parasitic order Strongylida, the

entomopathogenic genus Heterorhabditis and the order Diplogasterida. De Ley

and Blaxter (2002, 2004) updated the classification of the phylum Nematoda

using molecular data available from additional species, with morphological data

to assist the placement of taxa for which SSU sequences were not yet available.

They used SSU phylogenies to develop a novel classification reflecting recent

evolutionary findings and proposing the infraorders Cephalobomorpha,

Panagrolaimomorpha and Tylenchomorpha, all within a considerably expanded

suborder Tylenchina.

Nematodes of the suborder Cephalobina Andrassy, 1974 include an

ecologically and morphologically diverse array of species that range from soil

dwelling microbivores to parasites of vertebrates (Strongyloidoidea, including

Strongyloides) and invertebrates [entomopathogens used commercially for

biological control (Steinernema)]. Despite a long history of study, certain of these

microbivores (Cephaloboidea) present some of the most intractable problems in

    6 

 

nematode systematics (De Ley, 1997); the lack of an evolutionary framework for

these taxa has prevented the identification of natural groups and inhibited

understanding of soil biodiversity and nematode ecology.

The Cephaloboidea are a relatively distinctive group of widely distributed

bacterial-feeding soil nematodes, most frequently represented by the family

Cephalobidae, which includes more than 275 nominal species and 24 genera.

These nematodes, which are often striking in their labial morphology, are found

in soils worldwide and are typically the most abundant microbivores in nutrient-

poor soils such as deserts (Freckman and Mankau, 1986) and dry Antarctic

valleys (Freckman and Virginia, 1997). Despite their abundance and

cosmopolitan distribution, cephalobs have been among the most difficult

nematodes to diagnose, identify and classify. Historically these genera have

primarily been recognized based on variation in labial morphology, but molecular

phylogenies show the same general labial (probolae) morphotype often results

from recurrent similarity, a result consistent with the phenotypic plasticity of

probolae for some species in ecological time. The taxonomy, identification and

classification of cephalobs have become more difficult with time. For example,

genera that once seemed discrete based on morphological observations of

relatively few species have been blurred by discovery and description of

additional species with confounding character combinations, or overlaps between

characters previously considered diagnostic (De Ley, 1997). As a result, the

morphological characters originally proposed for distinguishing most genera are

now thought to be of questionable value, as demonstrated for Acrobeloides,

Cephalobus, Chiloplacus, Eucephalobus and Pseudacrobeles (De Ley, 1997).

    7 

 

More potentially disturbing are longstanding reports of substantial intraspecific

variation of lip structures within and between natural and in vitro cultured

populations of certain species of Cephalobidae (Allen and Noffsinger, 1972;

Anderson, 1965, 1968; Anderson and Hooper, 1970), with the range of variation

within single species sometimes exceeding differences used to discriminate

among genera. Addressing these systematic problems by developing a

phylogenetic framework for cephalobs is essential, because investigations of soil

biodiversity and ecology almost invariably require identification of cephalobs,

and taxa from this suborder are increasingly used as model organisms for

comparative developmental studies (Baldwin et al., 1997; Dolinski et al., 2001;

Félix et al., 2000; Goldstein et al., 1998; Schierenberg, 2000). Moreover, a

comprehensive phylogenetic framework for cephalobs has the potential to

provide insights into the evolution of features that may be associated with

nematode parasitism of plants, annelids, insects, and vertebrates.

Proposed phylogenetic affinities of cephalobs have been quite diverse.

For much of the early history of nematode taxonomy, cephalobs were considered

very closely related to rhabditids, the group that includes the premier nematode

model organism Caenorhabditis elegans. Other authors have proposed closer

affinities with certain predominantly parasitic nematodes, most notably with the

fungivorous or phytophagous tylenchs (Siddiqi, 1980), the annelid parasitic

drilonematids (Coomans and Goodey, 1965; De Ley and Coomans, 1990;

Lisetskaya, 1968; Spiridonov et al., 2005), and the entomopathogenic

steinernematids (Poinar, 1993). Regions of 28S rDNA subunit, including the

D2/D3 variable domains, have been used to infer relationships among certain

    8 

 

closely related species, primarily congeners (Baldwin et al., 2001; De Ley et al.,

1999; Nadler et al., 2003; Stock et al., 2001), Molecular phylogenies with

taxonomically broader representation for cephalobs have been inferred using

sequences from SSU (18S) ribosomal DNA (Blaxter et al., 1998; Félix et al.,

2000; Goldstein et al., 1998) and RNA polymerase II genes (Baldwin et al.,

1997). These studies have provided new insights into the relationships of

cephalobs to other major groups of nematodes, including the unexpected Wnding

that Tylenchida and Aphelenchida, which include the most economically

important plant parasites among nematodes, share most recent common ancestry

with cephalobs (Blaxter et al., 1998). A phylogeny of Cephaloboidea also

provides the opportunity to test the monophyly of other genera and examine their

relationships. Molecular phylogenetic trees can further serve as independent

frameworks for the investigation of morphological characters in nematodes

(Baldwin et al., 1997; Nadler & Hudspeth, 1998).

Recently Nadler et al. (2006) studied the phylogeny of Cephalobina. The

phylogenetic analyses of ribosomal (LSU) sequence data from 53 taxa revealed

strong support for monophyly of taxa representing the cephaloboidea, but do not

support the monophyly of most genera within this superfamily. Trees inferred

from LSU sequences, include a large clade containing most (but not all) genera

classically representing cephalobs plus plant parasites from the orders Tylenchida

and Aphelenchida. Published phylogenies inferred from SSU rDNA, although

including far fewer cephalob taxa, also recover this relationship (Blaxter et al.,

1998; Félix et al., 2000). Thus, both SSU and LSU sequence data indicate that

certain plant parasitic species share most recent common ancestry with

    9 

 

cephalobs, contrary to most traditional evolutionary concepts. Although the LSU

trees reveal that a large group of taxa normally classified as cephalobs are

monophyletic, the exclusion of certain genera and the close relationship of some

plant parasites indicates that even newer classification proposals for these taxa

(De Ley and Blaxter, 2002) will require some amendments to reflect these

findings. The LSU trees clearly refute the hypothesis that Macrolaimellus is more

closely related to chambersiellids (represented by Macrolaimus and Fescia in the

LSU trees), and strongly support its inclusion in Cephaloboidea.

Meldal et al. (2007) added SSU rDNA sequences for 100 un-sequenced

species of nematodes, including 46 marine taxa. Sequences for more than 200

taxa have been analysed based on Bayesian inference and logDet-transformed

distances. The phylogenetic analysis provided the support for the re-classification

of secernentea as the order Rhabditida that derived from a common ancestor of

chromadorean orders Araeolaimida, Chromadorida, Desmodorida,

Desmoscolecida and Monhysterida. Their analysis also support the the position of

Bunonema close to the Diplogasteroidea in the Rhabditina. Meldal et al. also

proved that SSU rDNA genes are very effective in the recovery of many

monophyletic group within the phylum Nematoda and provided clarification of

relationships that were uncertain or controversial. However, there were certain

limitations to the use of SSU. The SSU gene did not provide significant support

for the class Chromadoria or clear evidence for the relationship between the three

classes, Enoplia, Dorylaimia, and Chromadoria. Furthermore, across the whole

phylum, the phylogenetically informative characters of the SSU gene are not

informative in a parsimony analysis, highlighting the short-comings of the

    10 

 

parsimony method for large-scale phylogenetic modelling. Recently Abebe et al.

(2011) presented a review of the various techniques used in the taxonomy of free

living and plant parasitic nematodes and critique those methods in the context of

recent developments and trends including their implications in nematode

taxonomy, biodiversity and biogeography.

    11 

 

Historical Background

Although nematology attracted attention and recognition only in 20th

century, our knowledge of a few species of nematodes of medical importance

dates back to Papyrus Ebers (Circa 1500 BC). The intestinal round worm

(Ascaris lumbricoides), filarid (Wucheraria bancrofti) and guinea worm or fiery

serpent of Moses (Dracunculus medinensis) were already known to the ancient

man. However, marine, freshwater, soil and plant nematodes remained little

known groups mainly because of their extremely small size and the difficulties

encountered in their isolation, mounting and observation.

Knowledge of free-living nematodes dates back to 1656 when Borellus

for the first time observed Turbatrix aceti the ‘vinegar eels’. Observations and

descriptions of plant parasitic nematodes, which were less conspicuous to ancient

scientists, didn’t receive as much or as early attention as did animal parasites.

Needham (1743) solved the “riddle of cockle” when he crushed one of the

diseased wheat grains and observed “Aquatic Animals” the first plant parasitic

nematode (Anguina tritici). He found tiny serpent-like worms, which were later

named Vibrio tritici Steinbuch (1799). Muller (1783) described several species of

free-living freshwater nematodes. Nematode taxonomy further developed and

landmark progress was observed in the middle of 19th century. Around 1850,

marine biologists began to recognize nematodes; there were, studies on the

nematodes of Iceland (Leuckart, 1849), the Mediterranean (Eberth, 1863), the

English coast (Bastian, 1865), the coast of Brittany (Villot, 1875) and on

nematodes collected by various expeditions (Von Linstow, 1876). Freshwater

nematodes received further interest around 1890 with the papers of Daday (1897)

on the Hungarian fauna. Dujardin (1845), Bastian (1865), Schneider (1866), de

    12 

 

Man (1884), Daday (1905) and Maupas (1900) were the pioneers of the field.

Early work on the free-living nematodes included careful descriptions of

Enoplus, Oncholaimus, Rhabditis and Dorylaimus (Dujardin, 1845). He was first

to recognize the close relationship of free-living and plant parasitic nematodes.

Bastian (1865), made significant contributions in the field of Nematology. He

grouped the free-living nematodes into soil, fresh water and marine forms and

described 100 new species of 30 genera in which 23 were new to science, in a

single paper. de Man (1876-1927) listed eight families of free-living nematodes.

de Man’s (1884) formula for denoting measurements of nematodes is universally

used in taxonomy till date. Cobb, a contemporary of de Man, is considered, the

Father of Nematology. He placed nematodes under separate Phylum Nemata.

Significant changes in classification were proposed by Cobb (1920), De Coninck

(1965), Maggenti (1963, 70), and by Andrássy (1976, 84). In Chitwood’s (1933,

37) classification, ‘Nematoda’ was treated as a phylum with two classes,

‘Phasmidia’ and ‘Aphasmidia’, based on presence or absence of phasmids. The

terms Secernentea and Adenophorea were introduced by Chitwood (1958) who

proposed the system of classification of nematodes including free-living and

parasitic nematodes. Andrássy has contributed extensively to the taxonomy of

major groups of terrestrial and freshwater nematodes. In his productive career he

described more than 500 taxa of nematodes and at least 39 taxa were named after

him. Besides his voluminous contributions to nematode taxonomy and

systematics, he has had an enormous influence on soil and nematode ecology. He

published keys for identification, proposed and raised higher taxa, amended and

put forth classification schemes besides authoring valuable books including the

    13 

 

extremely useful compilation, ‘Klasse Nematoda' (1984) based on the diagnosis

of orders of Araeolaimida, Enoplida, Chromadorida, Monhysterida, and

Rhabditida and their subordinate taxa. This book exercised major influence on

the direction of nematode ecology in that it bridged the gap between nematode

taxonomy and soil ecology.

Order Rhabditida was erected by Chitwood (1933) for bacteriophagus

rhabditids. Dujardin (1845) first established the genus Rhabditis with Rhabditis

terricola as its type species. However it was not clearly defined until more than

one hundred year later (Dougherty, 1955). Örley (1880) proposed a family

Rhabditidae, for the genera Anguillula, Cephalobus, Oxyuris, Rhabditis and

Teratocephalus. He placed this family in the higher category “Rhabditi formae”

which formed a connecting link between free living and animal parasitic

nematodes. Micoletzky (1922) described seven species. His system was,

however, rather artificial in that he united all nematodes having a prismatic,

unarmed stoma under the family Rhabditidae, viz. the subfamilies

Cylindrolaiminae, Plectinae, Rhabditinae and Bunonematinae. The subfamily

Rhabditinae was itself heterogenous, and composed of the following genera:

Rhabditis, Diploscapter, Cephalobus, Chambersiella, Teratocephalus and

Rhodolaimus.

The record of cephalobid nematode can be traced back to 1656 when

Borellus observed “vinegar eels” for the first time. Muller (1783) named these

eels as Vibrio aceti, later on it was redescribed and shuffled to various taxa by

several authors, finally Peters (1927) proposed the genus Turbatrix and accepted

T. aceti as its type species. Though the first cephalob species “Cephalobus

    14 

 

persegnis” was formally described in 1865 by Bastian, it was not until the work

of Cobb (1924) and Thorne (1925, 1937) that basic taxonomic concepts and

terminology were established. Cobb (1924) rehabilitated the genus Acrobeles von

Linstow, 1877 and suggested the subgenera Acrobeles and Acrobeloides. Thorne

(1925) accepted the subgenera proposed by Cobb and produced a detailed

account on morphology, systematics and taxonomy of the genus Acrobeles. He

described thirty new species of Acrobeles and grouped them under two

subgenera. Thorne’s (1937) revision of the Cephalobidae has been of immense

value and importance. He (l.c) proposed subfamily Acrobelinae for genera

Placodira, Chiloplacus, Cervidellus and Zeldia and redescribed the genus

Acrobeloides. He also proposed superfamily Panagrolaimoidea with family

Panagrolaimidae and subfamily Panagrolaiminae. Later on he (1938, 39)

described the genera Panagrobelus and Panagrellus under Panagrolaiminae and

Stegellata under Acrobelinae. Simultaneously, Steiner (1934, 36, 38) proposed

the genus Procephalobus under the family Panagrolaimidae, and in Cephalobidae

the genera Eucephalobus, Tricephalobus and Pseudacrobeles were proposed.

Andrássy (1967) published detailed information on Cephalobinae

Filipjev, 1934. In 1974, he proposed the Suborder Cephalobina, to include an

incredibly diverse array of free-living microbivores. He included three

superfamilies Cephaloboidea Filipjev, 1934, Elaphonematoidea Heyns, 1962 and

Panagrolaimoidea Thorne, 1937 under Cephalobina. In Cephaloboidea he erected

the family Metacrobelidae and placed Metacrobeles Loof, 1962 under it. Further,

in 1984, he added two more superfamilies viz. Drilonematoidea Peirantoni, 1916

and Myolaimoidea Andrassy, 1958 under Cephalobina and accepted eight

    15 

 

families and ten subfamilies in these five superfamilies. He also proposed five

new genera Acrobelophis, Ypsylonellus, Stegelletina, Panagrocephalus and

Panagrobelium. Several other scientists who contributed to morphology and

taxonomy of cephalobids were Fuchs (1930), Filipjev (1934), Timm (1956, 60,

71), Brezeski (1960) and Loof (1962) who added few more genera and species to

the group.

Heyns (1962) published a series of papers on cephalobids and proposed a

superfamily Elaphonematoidea with family Elaphonematidae for the genus

Elaphonema. He also proposed family Osstellidae with subfamily Osstellinae for

the genus Osstella. In 1968 he described a genus Paracrobeles. Nesterov (1970)

proposed a genus Acromoldavicus and redescribed Acrobeloides skrjabini. Allen

and Noffsinger (1971, 72) revised the genus Zeldia and added few species

besides an identification key. They also proposed a new genus Nothacrobeles

under Acrobelinae and described four new species viz. N. sheri, N. lepidus, N.

maximus and N. subtilus and transferred Zeldia acrobeles to Nothacrobeles

acrobeles as a new combination.

Boström (1984-2000) worked extensively on the taxonomy of

cephalobids. He (1984a, b) described morphological variability of Chiloplacus

minimus and compared the morphological features of three species of

Eucephalobus viz., E. striatus, E. oxyuroides and E. mucronatus by light and

scanning electron microscopy. In 1985, he described four new species viz.

Acrobeles oosiensis, Zeldia brevicauda, Cervidellus neftasiensis, C. serratus,

redescribed Acrobeloides emarginatus (de Man, 1880) Thorne, 1937 and

proposed a new genus Acrolobus. He (1988a, b) further described Cervidellus

    16 

 

spitzbergensis, Acrobelophis minimus, Acrobeloides tricornis, Eucephalobus

articus and conducted the morphological and systematic studies to investigate the

structure and function of labial probolae of the family Cephalobidae. In 1989, he

gave description of three populations of Pangrolaimus viz. P. superbus, P.

rigidus and P. detritophagus. He (1990, `91, `92) reported Heterocephalobellus

putamiensis, Seleborca complexa, Zeldia punctata, Acrobeloides ciliatus and

Cervidellus serratus from the soil samples from Greece. Boström (1993a, b)

described Cephalobus persegnis and Eucephalobus striatus from Ireland and E.

hooperi and Acrobeloides nanus from Malaysia. He (1995) described

Panagrolaimus magnivulvatus from Antarctica and in 2000, he reported a

divergent population of Cervidellus capraeolus (De Ley, Geraert & Coomans,

1990) Boström & De Ley, 1996 from Bahamas.

Rashid, Geraert & Sharma (1984) also contributed to Cephalobina by

working on their morphology, taxonomy and systematics. They proposed two

new genera Cephalonema and Heterocephalobellus with C. longicauda and H.

brasilensis as their type respectively under the family Cephalobidae. They

described two new species viz. Heterocephalobus tabacum and Cephalobus

pseudoparvus and also proposed three synonyms: Acrobeles capensis as a junior

synonym of A. mariannae, the genus Pseudocephalobus as a synonym of

Teratolobus and the family Alirhabditidae as a synonym of the Cephalobidae.

Rashid et al. (1989) synonymized Acrobelinae with Cephalobinae mainly on the

basis of presence or absence of labial probolae and indentations of the head

border.

    17 

 

De Ley et al. (1990-97) added a good number of species besides

publishing revision of genera and also revised the terminology of stoma

components by studying the ultrastructure of the stoma in Cephalobidae,

Panagrolaimidae and Rhabditidae. Siddiqi (1993) proposed five new genera and

eight new species of Cephalobina. He (2002) also described a new genus

Catoralaimellus with C. cornutus as its type and two new species of

Macrolaimellus viz., M. crassus and M. filumicus. Velde et al. (1994) elucidated

the ultrastructure of buccal cavity and cuticle in three species of cephalobs.

Morphology, oviposition and embryogenesis of Acrobeloides nanus was studied

by Bird et al. (1994). Vinciguerra (1994) reported new genus Metacrolobus

festonatus. Vinciguerra and Clausi (1996) reported two new species of

Acrobelophis viz. A. lanceolatus and A. fuegensis from soil in Argentina. A new

genus Penjatinema was described and morphology of P. natalense was discussed

by Heyns and Swart (1998). Clausi (1998) reported Cervidellus vinciguerrae

sp.n. from the soil samples around the moss plants in Argentina. Karegar et al.

(1998) described one new and one known species of Stegelletina and three

species of Cervidellus. Holovachov et al. (2001) described a new genus

Acroukrainicus with A. sagittiferus as its type species. Further, Holovachov &

Boström (2006) proposed two new genera viz. Panagrolobus and Deleyia under

subfamily Cephalobinae and described three species P. vanmegenae, D. poinari

and D. aspiculata. Abolafia and Peña-Santiago (2002, 2003, 2006, 2009) added

several new species to various genera and revised the genera, Acrobeloides,

Chiloplacus, Pseudacrobeles, Nothacrobeles, Panagrolaimus, Cephalobus and

also provided keys to species identification.

    18 

 

Nematode problems of various kinds must have existed since time

immemorial. In India work on Nematology has been started as one of the

disciplines of agricultural sciences. Barber (1901) was the first to record the

infestation of root-knot nematode on tea in South India. During the period 1901-

1958 there had been very little progress, though there were historical breaking

discoveries (Barber, 1901; Butler, 1906, 1913, 1919; Ayyar, 1926, 1933; Dastur,

1936). Brief historical perspectives of the growth and development of

nematology in India have been reported by various authors in the past (Swarup et

al., 1967; Seshadri, 1965; Swarup and Seshadri, 1974).

Organized research on plant nematodes started only after the end of 1950.

The 1960s could be regarded as the most active phase for the growth of

nematology in general and nematode taxonomy in particular in India. Primarily,

nematological research in India has focussed more on the plant parasitic and

animal parasitic groups. Little work has been done on the free-living group-

Rhabditida, probably because they have no direct concern with agriculture and

livestock. Only a few scientists have worked on this heterogenous group during

the late 60s and 70s. One of the earliest reports was the description of Tridontus

longicaudatus Khera, 1965. Khera (1969) described Mesodiplogasteroides,

Operculorhabditis, Saprorhabditis and Praeputirhabditis and in 1970 he further

described two new genera viz. Paradoxogaster and Gobindonema. Later in 1971

he described Paradoxorhabditis in the subfamily protorhabditinae. Suryawanshi

(1971) described Tawdenema and Syedella which later on synonimized with

Acrostichus and Pareudiplogaster respectively. Jairajpuri et al. (1973)

redescribed Tridontus longicaudatus (Mononchoides longicaudatus) and

    19 

 

    20 

 

synonymised Syedella with Tridontus. Tahseen et al. (2005) and Ahmad et al.

(2007) described the new genera Metarhabditis and Sclerorhabditis respectively.

Recently, Ahmad et al. (2010), Mahamood & Ahmad (2009) added new species

under the genera Mesorhabditis, Diplogasteroides and Rhabditidoides

Similarly the studies on the taxonomy of cephalobid nematodes has not

been carried out extensively. Khera (1968), described the genus Acrobelinema (=

Chiloplacus) with A. cornis as its type species. Suryawanshi (1971) proposed the

genus Alirhabditis and erected the subfamily Alirhabditinae for this genus. Joshi

(1972) reported a new genus Pseudocephalobus (= Teratolobus) from

Marathwada. Ali et al. (1973) described two new species of Drilocephalobus and

proposed a new family Drilocephalobidae with a revised classification of the

superfamily Cephaloboidea. Rathore and Nama (1992) described two new

species viz. Acrobeloides conoidis and Chiloplacus jodhpurensis from Jodhpur..

Recently, Tahseen et al. (1999) made the morphometrical observations on the

populations belonging to subfamily Acrobelinae viz. Zeldia punctata,

Chiloplacus subtenius and Seleborca complexa through scanning electron

microscopy.

The present work has been divided into two parts. Part A deals with the

taxonomy and biodiversity of free living nematodes. The nematodes of suborder

Cephalobina have been described in this part. Cephalobids are typically the most

diverse and abundant microbivores found in the soils world wide. This group is

interesting because they were equally abundant in both type of habitats studied

(i.e. crop fields and wastelands) during present work. In India the work on the

taxonomy of this group has not been carried out extensively, so in the present

work the taxonomy is restricted to the nematodes of suborder Cephalobina. A

total of ten new and three already known species have been described and

illustrated. In Part B ecological aspects like nematode community structure and

ecological indices, in two different types of habitats (i.e. crop field and wasteland)

have been analysed and compared. Different indices have been calculated for

diversity and food web studies.

 

20a  

Materials &

Methods

Sampling: Samples for cephalobid nematodes were collected from agricultural

fields, wastelands, soil samples rich in organic debris, decayed and decaying

plant parts and farmyard manure from different parts of the country, especially

from Aligarh district and Eastern and Western Ghats of India. Some samples

from older collections were also screened. The samples were collected at regular

period throughout the year. The soil samples were taken from a depth of 10-20

cm and kept in airtight polythene bags. All relevant information such as host,

locality and date of collection were marked on the samples and these samples

were then brought to the laboratory for further processing.

Processing of soil samples: Samples were processed by modified Cobb’s (1918)

sieving and decantation and modified Baermann’s funnel techniques. From each

large sample, a sub-sample of about 500 cc was taken and mixed thoroughly with

water in a bucket taking care to remove debris and break the large clods and soil

crumbs. The bucket was then filled with water and the suspension was stirred to

make it homogenous. The mixture was kept undisturbed for about half a minute

so as to allow heavy matter to settle down to bottom of bucket. The suspension

was then passed into another bucket through a coarse sieve (2 mm pore size)

which retained large debris, roots and leaves etc. The suspension in the second

bucket was stirred thoroughly and was kept undisturbed for 30 seconds and then

poured through a fine sieve of mesh number 300 (pore size 53 µm). Nematodes

and very fine soil particles were retained on the sieve, the residue was then

collected in a beaker. This step was repeated 2 to 3 times for good recovery of

nematodes.

    21 

 

Isolation of nematodes: The residue collected in the beaker was poured on a

small coarse sieve lined with tissue paper. This sieve was then placed on a

Baermann’s funnel containing water sufficient to touch the bottom of the sieve.

Special care was taken to avoid trapping air bubbles at the bottom of the sieve.

The stem of the funnel was fitted with a rubber tubing provided with a stopper.

The nematodes migrated from the sieve into the clear water of the funnel and

accumulated at the bottom. After 24 hours, a small amount of water was drained

into a cavity block through the rubber tubing. The nematodes thus isolated were

fixed and processed for mounting on slides.

Killing and fixation: The collected nematodes in cavity blocks were left

undisturbed for a few minutes so as to allow them to settle down at the bottom.

Excess water was removed using a fine dropper and the hot FA fixative (8 ml of

40% commercial formaldehyde + 2 ml of glycerol + 90 ml of distilled water) was

poured into the cavity block. This act simultaneously killed and fixed the

nematodes.

Mounting and sealing: 24 hours after fixation, the nematodes were transferred

to a mixture of glycerine-alcohol (5 parts glycerine + 95 parts 30% alcohol) in a

cavity block, which was then in a desiccator containing anhydrous calcium

chloride. After 3 to 4 weeks the nematodes were dehydrated and were ready to be

mounted. A small drop of anhydrous glycerine was placed on a clean glass slide

and the nematodes were transferred from the cavity block into this drop. Either a

ring of wax was made or the pieces of wax were kept around the drop and a

    22 

 

circular glass cover slip was gently placed on the ring or pieces. This slide was

then heated on a hot plate. As the wax melted it sealed the drop of glycerine with

the nematodes.

Measurements and drawings: Measurements were made on specimens

mounted in dehydrated glycerine with an ocular micrometer. De Man’s (1884)

formula was used to denote the dimensions of nematodes. All morphological

observations, drawings and photographs were made on Olympus BX 50 and

Nikon 80i DIC microscopes.

Abbreviations used in the text

L = Total body length

a = Body length / greatest body diameter

b = Body length / distance from anterior end to the oesophago-intestinal junction

c = Body length / tail length

c´ = Tail length / anal body diameter

V = Distance of vulva from anterior end x 100 / body length

ABD = Anal body diameter

VBD = Vulval body diameter

Diam. = Diameter/diameters

    23 

 

Systematics

Order Rhabditida Chitwood, 1933

Diagnosis: Cuticle usually annulated, rarely ornamented with longitudinal striae

or punctations. Labial region mostly continuous, lips separate, three or six, often

with projections. Amphids small, inconspicuous, on lateral lips, exceptionally

large and more posterior in position. Mouth cavity of two main types: tuboid or

more or less spacious; in former case unarmed or possessing minute denticles, in

latter case usually provided with well developed teeth. Pharynx with either

median or terminal valvular bulb. Excretory pore visible. Intestine with wide

lumen. Three rectal glands generally present. Female reproductive system

didelphic or mono-prodelphic, in latter case generally with posterior uterine sac.

Ovaries reflexed. Ovi- or viviparous. Spicules ocassionaly fused. Male either

with paired genital papillae or with caudal bursa possessing paired rod like

papillae or ribs. Tail often different in each sex, without caudal; glands or

spinneret, but with distinct phasmids.

Type suborder: Rhabditina Chitwood, 1933

Other suborders: Cephalobina Andrassy, 1974

Diplogastrina Micoletzky, 1922

Myolaimina Inglis, 1983

Teratocephalina Andrassy, 1974

Suborder Cephalobina Andrassy, 1974

Diagnosis: Lips three or six, mostly separate; labial region often bearing

projections (probolae) of very various appearances. Amphids minute, pore-like,

on lateral lips. Mouth cavity tuboid, composed of six rings: cheilo-, gymno-, pro-,

    24 

 

meso-, meta- and telostom. The four latter (= stegostom) surrounded by

pharyngeal collar. Dorsal wall of metastom with a minute tooth-like projection.

Corpus and isthmus of pharynx well separated, terminal bulb possessing a well

developed grinder. Excretory pore distinct. Female genital system organ always

unpaired, prevulval, but ovary reflexed beyond the vulva. Spermatheca generally

present at anterior flexure of gonad. Predominantly oviparous. Spicules simple,

never fused, gubernaculum present. Male supplements papilloid, arranged in

pairs. No bursa. Tail generally short. Phasmids well discernible.

Type Superfamily: Cephaloboidea Filipjev, 1934

Other Superfamilies: Chambersielloidea Thorne, 1937

Panagrolaimoidea Thorne, 1937

Superfamily Cephaloboidea Filipjev, 1934

Diagnosis: Lip region varies from simple amalgamated type to those having

elaborate modified structures. Stoma quite narrow with uniformly sclerotized ring

elements, divided into three distinct sections, with or without metastomal tooth.

Oesophagus with or without grinders apparatus in the basal bulb. Female gonad

mono-prodelphic, reflexed, ovary extending beyond vulva, postvulval part in

most cases showing double flexures; spermatheca invariably present at anterior

flexure of gonad. Testis single, with reflexed terminal part. Spicules ventrally

curved with velum and capitulum. Gubernaculum present. Bursa absent. Genital

papillae present or absent.

Type family: Cephalobidae Filipjev, 1934

Other families: Elaphonematidae Heyns, 1962

Osstellidae Heyns, 1962

    25 

 

Family Cephalobidae Filipjev, 1934

Diagnosis: Cuticle annulated with sharply bordered lateral fields, occassionally

divided by longitudinal lines. Three cephalic probolae and three or six labial

probolae often present. Amphids located on lateral lips. Mouth cavity tuboid,

generally very narrow, ring elements small, uniformly sclerotized except for the

mostly unsclerotized gymnostom; cheilostom wider than the other rings. Dorsal

wall of metastom with minute tooth like projection. Pharynx consisting of usual

three sections, bulb strong. Vulval opening at two-thirds of body length, ovary

reflexed far posterior to vulva, its postvulval section in almost every case with

double flexures. Post-uterine sac present, generally short, rarely absent. Males in

general nearly as frequent as females. Phasmids distinct.

Type subfamily: Cephalobinae Filipjev, 1934

Other subfamilies: Acrobelinae Thorne, 1937

Acrolobinae De Ley, Siddiqi and Boström, 1993

Metacrobelinae Andrássy, 1974

Subfamily Cephalobinae Filipjev, 1934

Diagnosis: Lip region with simple cephalic and labial probolae, mostly

hexaradiate in symmetry, no deep clefts between lips. Cheilostom a broad

chamber, gymnostom short, dorsal metastegostom with a small tooth. Pharyngeal

corpus cylindrical, basal bulb with well developed grinder. Nerve ring usually

surrounding the base of corpus anterior to the isthmus. Female gonad single,

reflexed, ovary extending beyond vulva; spermatheca present at anterior flexure

of gonad. Males without bursa. Genital papillae present.

    26 

 

Type genus: Cephalobus Bastian, 1865

Other genera: Bunobus De Ley, Siddiqi & Boström, 1993

Eucephalobus Steiner, 1936

Heterocephalobellus Rashid, Geraert & Sharma, 1985

Heterocephalobus (Brzeski, 1960) Brzeski, 1961

Pseudacrobeles Steiner, 1938

Genus Pseudacrobeles Steiner, 1938

Diagnosis: Lateral fields with three incisures, fading out at or near the phasmids.

Lip region with hexaradiate, triradiate or bilateral symmetry and bearing 6+4

papilliform sensillae. Amphids small slits or oval pores at bases of lateral lips.

Lips separate or amalgamated; lateral lips may be reduced. Cephalic probolae

absent to short-setiform. Labial probolae absent to low knobs or ridges. Radial

ridges absent, tangential ridges present or absent. Mouth opening circular to

triangular, occasionally with small radial striae separating small liplet-like

structures but never extending deeply between the lips. Stoma with six sets of

sclerotizations. Cheilorhabdions comma-, bar- or granule- shaped in optical

section; cheilostom wide. Appearance of gymnostom in lateral view varying

from being as wide as cheilostom and having sclerotized rhabdia, to being as

narrow as stegostom and having inconspicuous rhabdia. Stegostom sections

clearly narrower than cheilostom. Females with post-uterine branch usually

developed, never surpassing ovary tip. Female tail sharp or blunt, conical, from

2.5 to 10 anal body diam. long. Male tail with or without mucro, with or without

    27 

 

extension of the body core beyond the posteriormost papillae. Gubernaculum

with cornua crurum never prominent.

Pseudacrobeles ventricauda sp. n.

(Fig. 1, 2)

Measurements: In Table 1.

Females: Body slender, slightly ventrally curved upon fixation, tapering

gradually towards both the ends. Cuticle transversely annulated, annules 1.4-2.0

µm wide at midbody. Lateral fields with three incisures, usually indistinct. Lips

separated, lip region with 6+4 papillae. Cephalic probolae setiform. Labial

probolae present, low. Stoma cephaloboid. Cheilostom with bar-shaped rhabdia;

gymnostom intermediate between cheilostom and stegostom in width and degree

of sclerotization. Stegostom narrow with weakly sclerotized rhabdia,

metastegostom with a minute dorsal tooth . Pharyngeal corpus cylindrical, 4.5-5.5

times isthmus length. Isthmus visibly demarcated from corpus by transverse

markings. Basal bulb pyriform, with grinders. Nerve ring surrounding the

posterior part of the corpus, at 65-70% of neck length. Excretory pore opposite

nerve ring, at 66-71% of neck length. Hemizonid and excretory pore are at the

same level. Intestine with distinct wide lumen. Cardia conoid, enveloped by

intestinal tissue.

Reproductive system mono-prodelphic. Ovary reversed, on right side of

intestine, with a double flexure or sometimes without any flexure posterior to

vulva. Oocytes arranged in one or more rows in the germinal zone and in single

or double row in maturation zone. Oviduct short. Spermatheca well developed

1.3 – 2.6 times corresponding body diam. long, containing spermatozoa. Uterus

    28 

 

well developed about 2-3 times the corresponding body diam. long, sometimes

with single ova in the lumen. Post-uterine sac 1.2-1.8 times the corresponding

body diam. long. Vagina thick-walled, 0.25-0.33 times the vulval body diam. Tail

elongate-conoid gradually tapering to a sharply pointed tip. A small subterminal

ventral projection is also present near the tail tip.

Males: General appearance similar to that of females. Habitus ventrally curved,

more in the posterior region. Reproductive system monorchic. Testis with

anterior ventral flexure on right side of intestine. Tail conical bearing an acute

mucro. Genital papillae eight pairs; two pairs precloacal (subventral), one

adcloacal (subventral) and five pairs postcloacal. Of the five postcloacal pairs,

two pairs (one subventral and one lateral) are anterior to phasmid, one subdorsal

pair posterior to phasmid and two subventral pairs near the tail terminus. Spicules

with rounded manubrium, slightly arcuate lamina and rounded tip. Gubernaculum

with well developed crura.

Type habitat and locality: Sandy soil collected from a grass bed near a river close

to the Rushikonda beach, Vishakapatnam.

Type specimens

Holotype female on slide Pseudacrobeles ventricauda sp. n./1; ten

females and ten males (paratypes) on slides Pseudacrobeles ventricauda sp. n./2-

8 deposited in the nematode collection of Department of Zoology, Aligarh

Muslim University, Aligarh.

Diagnosis and relationship

Pseudacrobeles ventricauda sp. n. is characterized by setiform cephalic

probolae, Cheilostom with bar-shaped rhabdia. Post-uterine sac 1.2-1.8 times the

    29 

 

corresponding body diam. long. Vagina thick walled, 0.25-0.35 times the vulval

body diam. Female tail elongate-conoid, with a small subterminal ventral

projection and acute tail terminus. Male tail conical, with fine terminal mucro.

The new species resembles Pseudacrobeles variabilis (Steiner, 1936)

Steiner, 1938 in general morphological characters and body size but differs from

it in having relatively longer post-uterine branch (36-47 µm vs 16-35 µm),

smaller c´ value in females (3.7-4.4 vs 4.6-7.2) and in the shape of female tail

(tail with a sub-terminal ventral projection vs tail terminus straight). The new

species also resembles P. tabacum (Rashid, Geraert & Sharma, 1985) De Ley,

Siddiqi & Boström, 1993 in morphological details. However, the new species

differs from P. tabacum in having comparatively longer pharynx in males (134-

156 µm vs 115-133 µm long), slightly smaller b-value both in males and females

(3.5-4.0 vs 4.0-4.5 in males and 3.4-4.1 vs 4.2-5.0 in females), longer post-uterine

branch 36-47 µm vs 22-31 µm), in the shape of female tail (tail terminus with a

ventral projection vs tail terminus without projection) and slightly smaller

spicules (19-21 µm vs 21-25 µm).

    30 

 

Table 1: Measurements (in µm) of Pseudacrobeles ventricauda sp. n. Mean and S.D. given in parenthesis

Characters Holotype

female Paratype females

(n= 10) Paratype males

(n= 10)

L 608 530-620 (587±27) 501-601 (556±34)

a 22.5 21.5-24.0 (22.8±0.8) 21.9-27.6 (24.7±1.5)

b 3.8 3.4-4.1(3.8±0.2) 3.5-4.0 (3.8±0.2)

c 8.5 7.8-8.8 (8.3±0.3) 12.6-14.5 (13.3±0.5)

c′ 4 3.7-4.4 (4.2±0.2) 2.0-2.4 (2.2±0.1)

V 59.5 57.5-60.5 (59±1.0) --

Maximum body width 26.5 23.5-27.5 (25.5±1.5) 20-25 (22.5±1.5)

Lip width 7 6-7 (6.7±0.4) 6-7 (6±0.3)

Lip height 4 3-4 (3.9±0.3) 3-4 (3.5±0.5)

Length of stoma 13 10-14 (12.5±1.0) 12-13 (12.3±0.5)

Corpus 117 99-123 (113±7) 95-115 (105±5)

Isthmus 23 20.5-26.5 (24.0±2.0) 18.0-27.5 (23.5±3.0)

Basal bulb length 21 18-22 (20±1) 18-19 (18.5±0.5)

Pharynx 159 138-166 (155±8) 133-156 (147±8)

Excretory pore from ant. end 106 96-114 (106±5) 94-108 (102±4.5)

Nerve ring from ant. end 106 96-112 (104±5) 89-106 (98.5±5.0)

Dierid from ant. end 124 121.5-133.5 (128±4) 112-126 (119.5±5.0)

Cardia 4 4-5 (4.5±0.5) 4.0

Basal bulb width 16 15-17 (15.5±0.5) 13-14 (13.1±0.4)

Anterior sac (Spermatheca) 35 32.5-67.5 (46.5±11.5) --

Genital branch 62 62.5-86.0 (76.0±6.5) --

Post-uterine branch 45 36-47 (40.5±4.0) --

VBD 27 23.5-28.5 (26.5±1.5) --

Vulva- anus distance 175 155-189(171±10) --

Rectum/cloaca 20 20-22 (21.0±0.5) 18-21 (19±1.0)

Tail 71 64.5-76.0 (70.5±3.5) 37.5-44.5 (42±2.0)

ABD 18 15-19 (17±1) 18-20 (18.5±1.0)

Phasmids from anus 18 16-21 (19.0±1.5) 17-22 (19.05±1.5)

Testis -- -- 224-295 (256±23)

Spicules -- -- 19-21 (20±0.5)

Gubernaculum -- -- 11-13 (12±0.5)

    31 

 

A

Fig. 2. Pseudacrobeles ventricauda sp. n. A. Anterior region showing stoma, B. Anterior region showing probolae, C. Spermatheca, D. Post-uterine sac, E. Female posterior region, F. Female tail terminus showing ventral projection, G. Spicules and gubernaculum, H. Male posterior region (Scale bars = 20µm).

33

B D

GC

E F H

Pseudacrobeles mucronatus sp. n.

(Fig. 3, 4)

Measurements: In Table 2.

Females: Body slightly ventrally curved after fixation. Cuticle about 1.0-1.5 µm

thick at mid body, with transverse annules. Annules about 1.7-2.2 µm wide at

mid body. Lateral fields occupying 14-22% of mid body diam., with three

incisures. Lip region with triradiate symmetry. Cephalic probolae varying from

distinctly setiform to completely absent. Labial probolae varying from small but

distinct knobs, to flat ridges formed by partially fused lips. Stoma cephaloboid,

cheilorhabdia bar shaped. Gymnostom intermediate between cheilostom and

stegostom in width and degree of sclerotization. Stegostom with distinguished

rhabdia, dorsal metarhabdion with a small tooth like projection. Pharyngeal

corpus cylindrical, 4.8-7.5 times isthmus length. Isthmus short 16.0-22.5 µm

long, Basal bulb pyriform, with well developed valves. Nerve ring lying in the

corpus region, at 57-78% of pharynx length. Excretory pore at the level, or upto

five annules posterior to the trailing edge of nerve ring. Dierid 4-7 annules

posterior to excretory pore. Cardia short, conoid surrounded by intestinal tissue.

Reproductive system mono-prodelphic, ovary directed posteriorly, with

oocytes generally arranged in one or two rows in the germinal zone and in a

single row in maturation zone. Oviduct short. Spermatheca well developed 0.5-

1.5 times corresponding body diam long. Uterus tubular, differentiated into

anterior glandular part, and posterior muscular part with distinct lumen. Post-

uterine sac 0.8-1.3 vulval body diam. long. Vagina thick walled. Vulva transverse

    34 

 

slit like. Rectum 1.2-1.6 anal body diam. long. Tail elongate conoid, 3.5-4.5 anal

body diam. long, with acute terminus. Phasmid at 23-34% of tail length.

Males: Anterior region of males similar to that of females. Variability in the lip

region is also in concurrence with females. Habitus ventrally curved, more in the

posterior region giving it a ‘J’ shaped appearance. Reproductive system

monorchic. Testis ventrally reflexed anteriorly, with flexure on right side of

intestine. Tail conoid with mucronate tip. Mucro either small (with blunt tip) or

long (with pointed tip). Genital papillae eight pairs; two pairs precloacal

(subventral), one adcloacal (subventral) and five pairs postcloacal. Of the five

postcloacal pairs, two pairs (one subventral and one lateral) are anterior to

phasmid, one dorsal pair posterior to phasmid and two subventral pairs near the

tail terminus. Spicules cephaloboid, rounded manubrium, calamus slightly

narrower than manubrium, lamina ventrally curved, with acute terminus.

Gubernaculum with well developed crura.

Type habitat and locality: Decaying organic matter and leaf litter collected from

Indira Gandhi Zoological Park, Vishakapatnam, Andhra Pradesh, India.

Type specimens

Holotype female on slide Pseudacrobeles mucronatus sp. n./1; nine

females and six males (paratypes) on slides Pseudacrobeles mucronatus sp. n. /2-

6, deposited in the nematode collection of Department of Zoology, Aligarh

Muslim University, Aligarh.

Diagnosis and relationship

Pseudacrobeles mucronatus sp. n. is characterized by three incisures in

lateral fields. Cephalic probolae varying from distinctly setiform to completely

    35 

 

absent. Labial probolae varying from small but distinct knobs to flat ridges.

Cheilorhabdia bar shaped. Gymnostom intermediate between cheilostom and

metastegostom in width and degree of sclerotization. Pharyngeal corpus

cylindrical, 4.8-7.5 times isthmus length. Males with mucronate tail tip. Mucro

either small (with blunt tip) or long (with pointed tip). Gubernaculum with well

developed crura.

The new species closely resembles Pseudacrobeles variabilis (Steiner,

1936) Steiner, 1938 in general morphological characters and body size. However,

new species differs from it in having smaller c´ value in females (3.6-4.5 vs 4.8-

7.2), larger corpus to isthmus ratio (4.8-7.5 vs 3.1-4.5 in females and 5.7-6.4 vs

3.1-4.2 in males) and slightly longer gubernaculum (12-14 µm vs 10-12 µm). The

new species also resembles P. baloghi Andrassy, 1968 in body size, shape of lip

region and morphometric values. However, the present species differs from P.

baloghi in having longer body in males (0.52-0.58 mm vs 0.4-0.51), smaller c´

value (2.0-2.4 vs 2.8-3.7), larger corpus to isthmus ratio (4.8-7.5 vs 2.9-4.2 in

females and 5.7-6.4 vs 3.2-4.0 in males), more posterior position of phasmid in

males (20-24 vs 13-19), in shape of male tail (mucronate tail tip vs tail tip with

body core extending in spike for 4-11µm) and slightly longer gubernaculum (12-

14 vs 10-12).

P. mucronatus sp. n. closely resembles P. tabacum Rashid et al., 1985 in

general morphometrics and morphology. However, differences were traced in the

shape of cheilostom (never in granular form vs bar to granule form), longer

pharynx in males (150-163 vs 115-131), smaller b value (3.2-4.0 vs 4.2-5.0 in

females and 3.3-3.6 vs 4.0-4.6 in males), position of nerve ring in females (57-72

    36 

 

% vs 73-74 % of the pharynx length), larger corpus to isthmus ratio in males (5.7-

6.4 vs 4.1-4.7). The new species also resembles P. laevis Thorne, 1937 in body

size, structure of cephalic and labial probolae and other morphological details.

However, differences were found in ‘a’ value (20.7-23.5 vs 24-28 in females and

19.5-23.8 vs 25-29 in males), ‘c’ value of females (8.3-10.0 vs 11-14) and

corpus:isthmus ratio (4.8-7.5 vs 3.3-4.5 in females and 5.7-6.4 vs 3.2-4.1 in

males).

    37 

 

Table 2: Measurements (in µm) of Pseudacrobeles mucronatus sp. n. Mean and S.D. given in parenthesis

Characters Holotype

female Paratype females

(n= 9) Paratype males

(n= 6)

L 534 492-640 (558±41) 518-583 (538±22)

a 20.7 20.7-23.5 (22.1±1.0) 19.5-23.8 (21.6±1.4)

b 3.5 3.2-4.0(3.8±0.2) 3.3-3.6 (3.4±0.1)

c 9.6 8.3-10.0 (9.4±0.7) 12.0-13.2 (12.7±0.4)

c′ 3.7 3.6-4.5 (4.0±0.3) 2.0-2.4 (2.2±0.1)

V 65.5 61.5-65.5 (63.5±1.5) --

Maximum body width 25.5 21.8-28.7 (25.0±2.0) 22.5-26.5 (25.0±1.5)

Lip width 7 7-8 (7.3±0.5) 7-8 (7.3±0.5)

Lip height 4 4-5 (4.2±0.4) 4.0

Length of stoma 13 13-15 (13.5±0.6) 13-14 (13.2±0.5)

Corpus 119 100-133 (120±9) 114-124 (120±4)

Isthmus 16 15.5-22.5 (20±2) 18-22 (19.5±1.5)

Basal bulb length 20 19-24 (20.5±1.5) 18-20 (19±0.7)

Pharynx 153 140-176 (159±10) 150-163 (158±5)

Excretory pore from ant. end 102 94-114 (103±5) 104-110 (105±2)

Nerve ring from ant. end 99 92-110 (101±5) 95-106 (100±3.5)

Dierid from ant. end 118 106-127 (116±6) 114-124 (117±3.5)

Cardia 4 4-5 (4.3±0.5) 4-5 (4.1±0.4)

Basal bulb width 16 14-18 (15±1.0) 14-16 (14.8±0.8)

Anterior sac (Spermatheca) 36.5 12-38 (37±8) --

Genital branch 64 48.5-77.0 (61.5±8.5) --

Post-uterine branch 29.5 17.5-38.5 (28.5±6.0) --

VBD 25.5 22.0-28.5 (25.5±2.0) --

Vulva- anus distance 128 127-159 (144±11) --

Rectum/cloaca 19 19-21 (20.0±0.5) 17-20 (18.5±1.5)

Tail 55.5 53.5-67.5 (59.5±4.0) 39.5-44.5 (42.5±1.5)

ABD 15 13-17 (15±1) 18-20 (19±0.5)

Phasmids from anus 16 14-22 (17.0±2.5) 20-24 (22±1.5)

Testis -- -- 208-268 (229±21)

Spicules -- -- 22-24 (23±0.7)

Gubernaculum -- -- 12-14 (13.2±0.7)

    38 

 

A

Fig. 4. Pseudacrobeles mucronatus sp. n. A-C. Anterior region showing variable lip region and stoma, D. Spermatheca, E. Post-uterine sac, F. Female posterior region, G. Lateral lines, H. Male posterior region, I&J. Male tail tip showing variable mucro length (Scale bars = 20µm).

40

B C

F

G

HJI

E

D

Subfamily Acrobelinae Thorne, 1937

Diagnosis: Lip region having cephalic probolae with complicated structures,

labial probolae large and exhibit triradiate symmetry, deep clefts present between

the lips. Cheilostom a broad chamber, gymnostom short, dorsal metastegostom

with a small tooth. Pharyngeal corpus cylindrical, basal bulb with well developed

grinder. Nerve ring usually surrounding the base of corpus or anterior half of

isthmus. Female gonad single, reflexed, ovary extending beyond vulva, straight

or with flexure posterior to vulva; spermatheca present at anterior flexure of

gonad. Males without bursa. Genital papillae present.

Type genus: Acrobeles Linstow, 1877

Other genera: Acrobeloides (Cobb, 1924) Thorne, 1937

Acrobelophis Andrassy, 1984

Acroukrainicus Holovachov, Boström & Susulovsky, 2001

Cervidellus Thorne, 1937

Chiloplacoides Heyns, 1994

Chiloplacus Thorne, 1937

Nothacrobeles Allen & Noffsinger, 1971

Paracrobeles Heyns, 1968

Pentjatinema Heyns & Swart, 1998

Placodira Thorne, 1937

Scottnema Timm, 1971

Stegelleta Thorne, 1938

Stegelletina Andrassy, 1984

Triligulla Siddiqi, 1993

Zeldia Thorne, 1937

    41 

 

Genus Acrobeles Linstow, 1877

Diagnosis: Body small to large (L=0.3-1.1 mm). Cuticle single or double, with

large annules, with or without longitudinal striae, punctations and/or pores.

Lateral field with two or three incisures, if cuticle double then often with

undulating internal pseudolines. Amphids relatively distinct, circular. Labial

probolae long, deeply bifurcated. Each prong with at least seven tines, its tip

usually with two elongate , separated apical tines.cephalic probolae high,

triangular, separate and fringed by numerous tines. Stoma cephaloboid with

distinct cheilorhabdia that are large and spherical in cross section. Pharyngea

corpus cylindrical to fusiform. Excretory pore position varying from very anterior

to opposite basal bulb. Female reproductive system cephaloboid, spermatheca

and post-uterine sac small to large. Vulva flush with body, occasionally sunken.

Males with three pairs of precloacal papillae, five pairs of postcloacal papillae

and one median papillae on the precloacal lip. Tails in both sexes conical, usually

with acute tip.

Acrobeles mariannae Andrassy, 1968

(Fig. 5)

Measurements: In Table 3.

Females: Body, straight to slightly curved ventrad, gradually tapering at both

extremities. Cuticle double, both layers similar, coarsely annulated. Annules

about 1.5-2.0 µm wide at mid body. Lateral fields with four incisures, slightly

elevated from body contour, outer incisures smooth, inner ones are crenate.

Labial probolae 7-11 µm high, bifurcated to about 50-60% of their length, each

    42 

 

arm bearing membranous tines varying in length and shape, rounded to rod-like,

and apical ones longer than the posterior ones. Inner sides with 6-8 tines and

outer sides with 7-9 tines, terminal tines ‘T’ shape. Cephalic probolae forming a

circle around the labials, each probola triangular, flap like, with 7 or 8 tines at

primary and secondary axil margins. Primary and secondary axils with similar

morphology (‘U’ shaped), with two guard processes each. Third tine of the

secondary axil is long and forwardly directed. Amphidial apertures rounded, at

the base of lateral cephalic probolae. Stoma cephaloboid, rhabdia distinctly

demarcated, cheilostom wide, with rounded rhabdia, gymnostom narrower than

cheilostom and as wide as stegostom, dorsal metarhabdion with tooth. Pharyngeal

corpus cylindrical 4-8 times longer than isthmus. Isthmus short, distinctly

separated from corpus by transverse marking. Basal bulb pyriform, with well

developed grinders. Nerve ring surrounding the corpus near corpus-isthmus

junction, at about 66-71% of pharynx length. Excretory pore far forward 26-38

µm from anterior end. Hemizonid in the posterior half of isthmus. Dierids at the

level of basal bulb. Cardia short, conoid surrounded by the intestinal tissue.

Intestine with small and granular cells, and wide lumen.

Reproductive system mono-prodelphic, ovary reversed, with or without

double flexure posterior to vulva. Oocytes arranged in one or two rows in the

germinal zone and in a single row in proliferative zone of ovary. Oviduct short.

Spermatheca reduced, less than the corresponding body diam. in length. Uterus

tubular, more than two corresponding diam. long, differentiated into a proximal

glandular and a distal muscular with thin walls. Post-uterine sac small, less than

the vulval body diam. in length. Vagina tubular, perpendicular to body axis, one

    43 

 

third of body diam. long. Vulva a transverse slit. Rectum 1.0-1.3 anal body diam.

long, anus an arcuate transverse slit. Tail conoid, gradually narrowing to an acute

terminus. Phasmids distinct, 33-39% or about one anal body diam. posterior to

anus.

Male: Not found.

Habitat and locality: Soil collected from the barren fields and road side ditches

near All India Radio station, Anoopshahr road, Aligarh.

Voucher specimen

Twelve females on slides Acrobeles mariannae/1-5 deposited in the

nematode collection of Department of Zoology, Aligarh Muslim University,

Aligarh.

Remarks

A. mariannae is a terrestrial species. It is widely distributed and is known

from The Netherlands, Hungary, Pakistan, Sudan, Kenya, Namibia, South Africa,

Brazil, Paraguay and Krakatau Islands, Hungary. This species is easily

differentiated from the other species of the genus by its small body and a very

anteriorly located excretory pore. The morphology and morphometric values of

our population of A. mariannae corresponds well with those of described

populations. A. mariannae is reported for the first time from India.

    44 

 

Table 3: Measurements (in µm) of Acrobeles mariannae Andrassy, 1968 Mean and S.D. given in parenthesis

Characters Females (n=10)

L 440-497 (472 ± 20)

a 15.7-18.3 (16.9 ± 1)

b 3.6-4.1 (3.9 ± 0.15)

c 9.5-11.9 (10.6 ± 0.6)

c′ 2.3-3.0 (2.6 ± 0.2)

V 60-62 (61 ± 0.5)

Maximum body width 25-30 (28 ± 1.5)

Lip width 13-14 (13.1 ± 0.4)

Stoma length 11-14 (11.5 ± 1)

Corpus 79-86 (84 ± 2)

Isthmus 11-22 (16 ± 4)

Basal bulb length 21-23 (21.5 ± 0.5)

Basal bulb width 15-18 (16 ± 1)

Pharynx 114-128 (122 ± 5)

Excretory pore from anterior end 26-38 (33 ± 3.5)

Nerve ring 74-89 (82 ± 4)

Cardia 5-6 (5.5 ± 0.5)

Anterior sac (Spermatheca) 6-13 (9 ± 2)

Genital branch 46.5-79.0 (63 ±10)

Post-uterine sac 9-16 (13.5 ± 2)

Vulval body diameter (VBD) 24-30 (28 ±1.5)

Vulval anus distance 131-153 (141 ± 8.5)

Rectum 18-20 (19 ± 1)

Tail 41-48 (45 ± 2)

Anal body diameter (ABD) 15-19 (17 ± 1.5)

Phasmids from anus 15-17 (16 ± 0.5)

    45 

 

Genus Acrobeloides (Cobb, 1924) Thorne, 1937

Diagnosis: Body length varying from 0.3-1.2 mm. cuticle annulated, lateral fields

with two to five incisures extending generally to tip of tail. Lips three, labial

probolae hemispheroid or conoid, point always uni-tipped. Cephalic probolae

present, but low, not strongly differentiated. Proximal half of oesophagous,

fusiform. Stoma cephaloboid, narrow. Vulva near two-thirds of body length,

ovary with double postvulval flexures. Males mostly unknown. Tail short and

plump, broadly rounded or conoid.

Acrobeloides glandulatus sp. n.

(Fig. 6, 7)

Measurements: In Table 4.

Females: Body cylindrical, tapering gradually towards both ends, slightly

ventrally curved after fixation. Cuticle with strong transverse annules, annuli 3-

4µm wide at midbody. Lateral fields 22-30% of the mid-body diam., with five

incisures; outer incisures crenate and irregularly aerolated. Lips six, amalgamated

in pairs, flattened. Primary axils distinct, with smooth margins. Secondary axils

scarcely demarcated. Three low and rounded labial probolae. Amphidial

apertures slit-like. Stoma cephaloboid. Cheilostom wide, with small and ovoid

rhabdia, gymnostom and stegostom slightly narrower than cheilostom,

metastegostom with a small tooth on dorsal rhabdia. Pharyngeal corpus

cylindrical, 4.7-7.5 times isthmus length. Corpus-isthmus junction distinguished

by transverse markings. Isthmus smaller than basal bulb. Basal bulb ovoid or

pyriform, with strongly developed grinder. Nerve ring surrounding the isthmus in

    47 

 

anterior half, or at 73-78% of neck length. Excretory pore at the level of basal

bulb, 77-92% of neck length. Dierids at level or slightly posterior of basal bulb

region. Cardia conoid, surrounded by intestinal tissue. Intestine with distinct wide

lumen, intestinal cells small, granular in appearance with distinct nuclei.

Reproductive system mono-prodelphic. Ovary reversed, straight or with

double flexure in its postvulvular part. Oocytes arranged in two or more rows in

the germinal zone. Oviduct short, tubular. Spermatheca 0.6-2.0 times the

corresponding body diam. long, with few sperms. Uterus long, differentiated in

an elongated proximal glandular part and a short distal muscular part with wide

and distinct lumen. Post-uterine sac 1-2 vulval body diam. long. Vagina with

thick walls, one-third of body diam. A pair of spheroid glands associated with the

vagina, each gland is arranged on either side of vagina, both glands seems to

open into the vaginal lumen through a common duct. Vulva transverse, lips

slightly protruded. Rectum less than one anal body diam. long. Tail conoid, 1.7-

2.1 anal body diam. long, with rounded terminus. Phasmid at 46 – 55 % of tail

length.

Males: General appearance similar to that of female, but with slightly smaller

body, ventrally curved in the posterior region adopting ‘J’ shape. Reproductive

system monorchic. Testis reflexed ventrally anteriorly on the right side of

intestine. Tail conoid, ventrally curved, with rounded terminus. Genital papillae

eight pairs; three pairs pre-cloacal (subventral), five pairs post-cloacal. Of the

five post-cloacal pairs two pairs (one subventral and one lateral) anterior to

phasmid, three pairs (one dorsal, one lateral and one subventral) near the tail

terminus. Spicules strong, small manubrium, calamus broad, slightly ventrally

    48 

 

curved lamina with pointed tip. Gubernaculum straight, more than half of spicule

length, narrow and pointed distally.

Type habitat and locality: Soil collected from a ploughed field at Nohati village,

Madrak, Aligarh.

Type specimens

Holotype female on slide Acrobeloides glandulatus sp. n./1, nine females

and eight males (paratypes) on slides Acrobeloides glandulatus sp. n./2-10

deposited in the nematode collection of Department of Zoology, Aligarh Muslim

University, Aligarh.

Diagnosis and relationship

Acrobeloides glandulatus sp. n. is characterized by a body length of 625-

825 µm in females and 558-717 µm in males. Lateral fields with five incisures.

Low and rounded labial probolae. Pharyngeal corpus 4.7-7.5 times isthmus

length. Well developed spermatheca (0.6-2.0 times corresponding body diam.

long) and long post-uterine sac (1-2 vulval body diam. long). Presence of one pair

of gland on either side of vagina. Spicules 41-48 µm long. Straight

gubernaculum, with narrow and pointed distal end.

The new species resembles Acrobeloides bodenheimeri (Steiner, 1936)

Thorne, 1937 in general morphological characters, morphometric values and

body size but differs from it in having longer post-uterine sac (57-72 µm vs 29-55

µm), variable shape of ovary (with or without double flexure vs with double

flexure), larger corpus-isthmus ratio (5-8 vs 3.8-4.2), longer spicules (41-48 µm

    49 

 

vs 35-39 µm) and in the shape of gubernaculum (straight and pointed distal tip vs

ventrally curved and blunt distal tip).

    50 

 

Table 4: Measurements (in µm) of Acrobeloides glandulatus sp. n. Mean and S.D. given in parenthesis

Characters Holotype

female Paratype females

(n= 9) Paratype males

(n= 8)

L 825 625-825 (746±58.5) 558-717 (644±53)

a 17 15.8-19.3 (17.6±1.2) 14.5-18.2 (16.2±1.2)

b 5.4 4.5-5.5 (5.1±0.3) 4.3-5.1 (4.9±0.2)

c 19 15.4-19.0 (17.3±1.2) 14.5-17.0 (15.5±0.9)

c´ 1.9 1.7-2.1 (1.9±0.13) 1.5-1.8 (1.6±0.1)

V 69 68-71 (69.5±1.0) --

Maximum body width 47 32.5-50.5 (43.0±6.0) 30.5-47.5 (40.0±4.5)

Lip width 12 11-13 (11.5±0.7) 10-12 (11.0±0.5)

Lip height 5 5-6 (5.4±0.5) 5-6 (5.1±0.3)

Length of stoma 14 13-14 (13.7±0.5) 13-14 (13.2±0.4))

Corpus 109 102-110 (105.5±3.0) 81-106 (93.5±7.0)

Isthmus 17 14-22 (17±2.5) 15-20 (17±20)

Basal bulb length 26 22.0-26.5 (24.5±1.5) 19.0-23.5 (21.5±2.0)

Pharynx 153 138-152 (146±5) 120-146 (132±9)

Excretory pore from ant. end 126 115-130 (124±5.5) 101-130 (115±11)

Nerve ring from ant. end 112 103-113 (109±3.5) 85-102 (96±6)

Dierid from ant. end 136 126-141 (133.5±5.5) 108-138 (124±10)

Anterior sac (Spermatheca) 54 23-72 (44±13) --

Genital branch 215 137-274 (206±41) --

Post-uterine branch 59 57-72 (64±6) --

VBD 42 32.5-50.5 (41±5.5) --

Vulva- anus distance 214 160-214 (184±16) --

Rectum/cloaca 25 20-26 (24.5±1.5) 33-41 (36±2)

Tail 43 40.5-45.5 (43.5±1.5) 36.5-44.5 (41±2.0)

ABD 23 19-25 (22.5±1.5) 20.5-29.5 (25.5±2.5)

Phasmids from anus 20 20-25 (21.5±2.0) 20-27 (24±2)

Testis -- -- 294-381 (343±32)

Spicules -- -- 40.5-47.5 (43.5±2.5)

Gubernaculum -- -- 21.5-27.5 (25.5±2.0)

    51 

 

A B C

I

D

E

F

HG J

Fig. 7. Acrobeloides glandulatus sp. n. A&B. Anterior region showing stoma and lip region, C. Glands associated with vagina, D. Vulval region, E&F. Cuticular markings, G&H. female posterior region, I&J. Male posterior region showing spicules and gubernaculum (Scale bars = 20µm).

53

Genus Cervidellus Thorne, 1937

Diagnosis: Very small nematodes ranging from 0.3 to 0.5mm. Cuticle finely

annulated, lateral fields with two, three or five incisures. Lip margins with U-

shaped refractive elements, cephalic probolae six, triangular or leaf-like. Labial

probolae thin, Y-shaped, occasionally with secondary tines. Pharyngeal corpus

cylindrical. Female genital apparatus cephaloboid. Tails of both sexes conoid

with pointed tip.

Cervidellus neoalutus sp. n.

(Fig. 8, 9)

Measurements: In Table 5.

Females: Body slender, slightly ventrally curved after fixation, gradually tapering

towards both extremities. Cuticle double, transversely annulated, each annule

with two rows of punctations. Annuli 1.8-2.2 µm wide at pharyngeal region and

about 1.7-2.0 µm wide at midbody and tail region. Lateral fields with four

crenated incisures, without areolation, covering about 1/5th of body diam. at

midbody. Lateral lines start at 40-50% of pharynx length from anterior end as

two faint lines and differentiate into four lines at level of basal bulb. The two

inner incisures are more widely separated as compared to the outer ones,

appearing as two pairs of four lines. All incisures reach the tail terminus.

Cephalic region with six probolae, each consisting of five leaf-like elements: in

the centre, the longest and slightly clavate element; more outwards and on both

sides two pairs of shorter and acute elements. Labial probolae about 5µm long

with bifurcation at two levels, primary bifurcation at 2/3rd of probolae length,

    54 

 

secondary bifurcation apical. Amphidial apertures small, rounded. Stoma

cephaloboid. Cheilostom wide, with granular rhabdia. Gymnostom and stegostom

with less distinct rhabdia, narrower than cheilostom. Dorsal metastegostom with

a minute tooth like projection. Pharyngeal corpus cylindrical 2.5-3.0 times

isthmus length. Basal bulb pyriform or ovoid with well developed grinder. Nerve

ring at 63-71 % of neck length, surrounding isthmus in its anterior half. Excretory

pore at the level or slightly anterior to nerve ring. Dierids in the isthmus region, at

71-78% of neck length. Cardia rounded to conoid, surrounded by intestinal tissue.

Intestinal walls with differentiated rectangular cells, intestine with wide lumen.

Reproductive system mono-prodelphic. Ovary reversed, extending

posterior to vulva, postvulval flexure absent. Oocytes with large nuclei, arranged

in a single or double row in the germinal zone and in a single row in the

maturation zone. Oviduct short, spermatheca well developed, about 1.5 vulval

body diam. long. Uterus simple, tubular with narrow lumen and without any

differentiation. Post-uterine sac 1.0-2.5 times vulval body diam. long. Vagina

narrow, tubular, one-fourth of body diam. Vulval opening a small transverse slit.

Tail conical, with acute terminus. Phasmids distinctly visible, about 0.6-1.0 anal

body diam. posterior to anus.

Males: Anterior region similar to that of females. Reproductive system

monorchic. Testis reflexed ventrad anteriorly, on right side of intestine. Spicules

cephaloboid, manubrium round, calamus slightly narrower than manubrium,

lamina ventrally curved, with acute terminus. Gubernaculum straight, with well

developed crura. Genital papillae seven pairs, three pairs precloacal (subventral)

and four pairs postcloacal. Out of the four postcloacal papillae, two pairs (one

    55 

 

subventral & one lateral) anterior to phasmid and two pairs (one subdorsal & one

lateral) posterior to phasmid. A mid-ventral papilla on the anterior cloacal lip is

also present.

Type habitat and locality: Soil from a barren field near Central School, Bad

village, Mathura.

Type specimens

Holotype female on slide Cervidellus neoalutus sp. n./1, nine females and

three males (paratypes) on slides Cervidellus neoalutus sp. n./2-8 deposited in

the nematode collection of Department of Zoology, Aligarh Muslim University,

Aligarh.

Diagnosis and relationship

Cervidellus neoalutus sp. n. is characterized by a double cuticle, lateral

fields with four crenate incisures with inner ones more widely separated than

outer ones. Symmetrical lips, with refractive elements, labial probolae with

bifurcation at two levels and small post-uterine sac about 1.2-2 times vulval body

diam. in length.

The new species closely resembles C. alutus (Siddiqi, 1993) Shahina and

De Ley, 1997 in having double cuticle, symmetrical lips with refractive elements

but differs from it in the length of stoma (14-15 µm vs 10 µm), smaller post-

uterine sac (1.2 – 2 vs 2.3 - 2.6 times vulval body diam. long) and in the presence

of males (males absent in C. alutus).

    56 

 

Table 5: Measurements (in µm) of Cervidellus neoalutus sp. n. Mean and S.D. given in parenthesis

Characters Holotype female

Paratype females (n= 9)

Paratype males (n= 3)

L 554 485-566 (529.5±23) 500-538 (522±16.5)

a 20.7 18.3-22.3 (20±1.3) 17.5-19 (18.5±0.7)

b 3.9 3.5-3.9 (3.7±0.2) 3.5-4.0 (3.8±0.2)

c 10.4 9.8-11.3 (10.3±0.4) 13.5-14.5 (14±0.5)

c’ 3.2 2.7-3.3 (3.1±0.2) 1.8-2.0 (1.9±0.1)

V 59 57-59 (58.5±0.5) --

Maximum body width 26.5 22-31 (26.5±2.3) 28-29 (28.5±0.5)

Lip width 13 12-13 (12.5±0.5) 12-13 (12.5±0.5)

Lip height 7 6-7 (6.5±0.5) 7

Length of stoma 14 14-15 (14.5±0.5) 14

Corpus 86 85-90 (87±1.5) 85-87 (86.5±1.0)

Isthmus 32.5 27.5-33.5 (31.5±2.0) 24.5-31.5 (28.5±3.0)

Basal bulb length 22.5 21-24 (23±1.0) 22-24 (22.5±1.0)

Pharynx 141.5 135-145 (142±3.5) 136-141(138±4)

Excretory pore from ant. end 96 84-96 (92±3.5) 96-97 (96.5±0.5)

Nerve ring from ant. end 101 87-101 (94±3.5) 92-96 (94.5±1.5)

Dierid from ant. end 111 98-112 (107±5) 110

Basal bulb width 15 14-16 (15.5±0.5) 15-16 (15.2±0.5)

Anterior sac (Spermatheca) 37.5 29-43.5 (37±4.5) --

Genital branch 51 44.5-63.5 (50.5±5.5) --

Post-uterine branch 51 35.5-59.5 (47±7) --

VBD 27 22-31 (26±2.5) --

Vulva- anus distance 173 157-179 (167±7) --

Rectum 18 15-20 (18±1.5) --

Tail 53 48.5-55.5 (52±2.5) 37-39 (37.5±1.0)

ABD 17 15-19 (17±1) 20-21 (20.2±0.5)

Phasmids from anus 17 11-17 (15±2) 15-17 (16±1.0)

Testis -- -- 229-274 (246 ± 20)

Spicules -- -- 22-23 (22.5±0.5)

Gubernaculum -- -- 12-13 (12.5±0.5)

    57 

 

Fig. 9. Cervidellus neoalutus sp. n. A. Anterior region showing amphidial aperture, B&C. Anterior region showing probolae and stoma, D. Spermatheca, E. Post-uterine sac, F. Female posterior region, G. Male posterior region, H. Spicules and gubernaculum, I. Lateral lines (Scale bars = 20µm).

59

A B C

GED

F I H

Cervidellus minutus sp. n.

(Fig. 10, 11)

Measurements: In Table 6.

Females: Body small, slightly ventrally curved after fixation. Cuticle simple, with

transverse annulations. Lateral fields 12-14% of mid-body diam. wide, with three

incisures. Outer incisures crenate extending up to tail tip, central incisure ends at

phasmids. Cephalic probolae six, with refractive margins, each consisting of five

leaf- like elements. Primary and secondary axils similar in shape. Labial probolae

reduced, rarely visible in light microscope. Amphidial apertures small, ovoid.

Cheilostom with granular rhabdia, gymno- and stego-rhabdions poorly

developed. Pharyngeal corpus slightly fusiform, sometimes with wide lumen, 3.1-

3.7 times isthmus length. Corpus-isthmus junction distinguished by faint

transverse markings. Basal bulb spheroid, with well developed grinder. Nerve

ring at 56-61% of neck length, encircling isthmus in its anterior half. Excretory

pore at the level or just posterior to corpus-isthmus junction. Excretory duct

distinctly sclerotized. Dierids in the isthmus region or at the level of basal bulb.

Intestine with wide lumen. Cardia conoid about 2-3µm long, surrounded by

intestinal tissue.

Reproductive system mono-prodelphic, on right side of intestine. Ovary

reversed, without flexure posterior to vulva. Oocytes arranged in a single or

double row in germinal zone and in a single row in proliferative zone. Oviduct

short, not clearly demarcated. Spermatheca weakly developed, smaller than the

corresponding body diam. Uterus uniform in thickness, without any

differentiation between glandular and muscular part, lumen not visible. Post-

    60 

 

uterine sac less than one vulval body diam. long. Vagina straight, about 1/3rd of

body diam. with slightly thickened walls. Vulva transverse, slit like. Rectum

slightly more than one anal body diam. long. Rectal glands barely visible. Tail

conical, about 2-3 anal body diam. long, terminus acute, with subterminal dorsal

projection. Phasmids with distinct opening, about half anal body diam. posterior

to anus.

Male: Not found.

Type habitat and locality: Collected from the rhizosphere of Guava (Psidium

guajava) and Cashew-nut (Anacardium occidentale), in mixed plantation, from

Satpada, near Chilka lake, Orrisa, India.

Type specimens

Holotype female on slide Cervidellus minutus sp. n./1 and five females

(paratypes) on slides Cervidellus minutus sp. n./2-4 deposited in the nematode

collection of Department of Zoology, Aligarh Muslim University, Aligarh.

Diagnosis and relationship

Cervidellus minutus sp. n. is characterized by its small body (226-266

µm), lateral fields with three incisures. Lips with refractive margins. Reduced

labial probolae. Distinctly sclerotized excretory duct. Small spermatheca (5-6

µm) and post-uterine sac (less than one anal body diam.). Conoid tail, with acute

terminus and hook-like subterminal dorsal projection.

The new species differs from all other species of the genus in having a

subterminal dorsal projection in female tail. It, however, closely resembles C.

neftasiensis Boström, 1986 and C. vexilliger (de Man, 1880) Thorne, 1937 in

general morphometrics, shape of labial region, number of lateral lines. It can be

    61 

 

differentiated from C. neftasiensis in having comparatively smaller body length

(226-266 µm vs 268-330 µm), smaller spermatheca (5-6µm vs 13-28µm), and

relatively smaller genital branch (26-36µm vs 37-71µm). C. minutus sp. n. also

differs from C. vexilliger in having smaller spermatheca (5-6 µm vs 11-37 µm)

and relatively smaller post-uterine branch (7-8 µm vs 8-47 µm).

    62 

 

Table 6: Measurements (in µm) of Cervidellus minutus sp. n. Mean and S.D. given in parenthesis

Characters Holotype

female Paratype females

(n= 5)

L 253 226-266 (251±13)

a 17 16.3-18.8 (17.1±0.8)

b 3 2.9-3.1 (3±0.1)

c 12.2 10.5-12.2 (11.5±0.6)

c’ 2.3 2.3-2.8 (2.5±0.1)

V 67 63.5-66.5 (64.5±1.0)

Maximum body width 15 14-16 (14.5±0.5)

Lip width 8 8-9 (8.5±0.5)

Lip height 5 5-6 (5.2±0.5)

Length of stoma 7 6-8 (7±0.5)

Corpus 56 50.5-56.5 (55±2)

Isthmus 16 14-18 (16±1.5)

Basal bulb length 13 12-13 (12.5±0.5)

Pharynx 85 77-86 (83.5±3)

Excretory pore from ant. end 53 51.5-59.5 (54.5±2.5)

Nerve ring from ant. end 48 47.5-51.5 (49.5±1.5)

Dierids from ant. end 67 67.5-69.5 (67.5±1)

Basal bulb width 9.9 9.9

Anterior sac (Spermatheca) 5 5-6 (5.5±0.5)

Genital branch 32 26-36 (31±4.5)

Post-uterine branch 8 7-9 (7.5±0.5)

VBD 14 13-15 (13.5±0.5)

Vulva- anus distance 63.5 61-73 (67±4)

Rectum 12 10-12 (11.5±1.0)

Tail 21 20-24 (22±1.5)

ABD 9 8-10 (8.5±0.5)

Phasmids from anus 5 4-5 (4.2±0.4)

    63 

 

A B C

ED

F

GFig. 11. Cervidellus minutus sp. n. A. Pharyngeal region, B Anterior region showing cephalic

probolae with refractive margins, C Anterior region showing stoma, D. Lateral lines, E Female reproductive system, F. Posterior region, G. Tail tip showing dorsal projection (Scale bars = 20µm).

65

Genus Chiloplacus Thorne, 1937

Diagnosis: Body 0.3-1.0 mm long. Cuticle annulated, lateral fields with 3-6 lines.

Lips three. Labial probolae biacute or bifurcate (apically incised), symmetrical or

assymetrical, with broad “shafts”. Cephalic probolae small, generally with two

incisures. Pharyngeal corpus cylindrical. Post-vulval uterine sac of variable

lengths. Female tail straight, short, cylindroid, terminus broadly rounded. Male

tail ventrally bent, phasmids posterior to lateral caudal papilla.

Chiloplacus aligarhensis sp. n.

(Fig. 12, 13)

Measurements: In Table 7.

Females: Body slender, straight or slightly ventrally curved after fixation. Cuticle

annulated, annules 2.3-3.3 µm wide at mid-body, with irregular punctations

throughout the body length. Lateral fields about 1/4th body diam. at midbody,

with five incisures. Lateral lines arise at about two stoma lengths from anterior

end and from middle of procorpus differentiate into five lines that extends upto

the tail terminus except the central incisure that ends at phasmids. Lip region with

six lips. Cephalic probolae small, with deep primary axils and shallow secondary

axils. Labial probolae high (6-7µm), with shallow bifurcation forming finely

developed prongs. Stoma cephaloboid, rhabdions clearly differentiated;

cheilostom wide with minute oval or triangular rhabdia, gymnostom slightly

narrower than cheilostom and as wide as stegostom, metastegostom with small

tooth like projection. Pharyngeal corpus cylindrical, 8-11 times isthmus length.

Corpus-isthmus junction demarcated by faint transverse markings. Isthmus short,

    66 

 

17-22 µm long, basal bulb ovoid, with well developed grinder. Nerve ring

surrounding corpus in its posterior half, at 60-66% of pharynx length. Excretory

pore at 60-72% of pharynx length. Dierids 5-8 annules posterior to excretory

pore. Cardia short, conoid, surrounded by intestinal tissue. Intestine with wide

lumen and thin walls in its anterior region, cell differentiation not visible in

anterior and posterior regions of intestine. Cells in the mid-intestine region well

differentiated, rectangular in shape, granular in appearance with distinct nuclei.

Reproductive system mono-prodelphic, ovary reversed, without flexure

posterior to vulva, sometimes with swollen germinal portion with oocytes

arranged in one or two rows. Oocytes in a single row in the proliferative zone.

Oviduct short. Spermatheca well developed, longer than the corresponding body

diam.. Uterus tubular, more than two corresponding body diam. long,

differentiated into a proximal glandular part and a distal swollen muscular part

with thin walls. Post-uterine sac well developed, 2.5-4.0 vulval body diam. long.

Vagina muscular, anteriorly inclined, about half of vulval body diam. long. Vulva

transverse, slit-like, vulval lips may be slightly protruded. Rectum 1.0-1.3 anal

body diam. long. Tail subcylindrical with rounded terminus. Phasmids distinct,

1.0-1.5 anal body diam. posterior to anus.

Males: General morphology similar to that of females. Body J-shaped after

fixation. Reproductive system monorchic. Testis reflexed ventrally anteriorly,

with flexure on right side of intestine. Apical germinative zone with three to four

rows of spermatogonia, maturation zone with spermatocytes and differentiated

sperms at its distal end. Vas deferens highly granular in appearance without any

valve or sphincter at the junction of maturation zone. Ejaculatory duct with

    67 

 

similar appearance as of vas deferens but with distinct lumen containing sperms.

Tail conoid, ventrally curved. Genital papillae eight pairs; three pairs pre-cloacal,

ventro-lateral in position and five pairs post-cloacal. Of the post-cloacal pairs,

one ventro-lateral and one lateral pair anterior to phasmids, one pair dorso-lateral

near tail terminus and two terminal ventro-lateral pairs. A single median pre-

cloacal papilla present on the anterior cloacal lip. Spicules slightly ventrally

arcuate, manubrium round and bent ventrally, calamus with thin walls, lamina

thick, ventrally curved, bearing a longitudinal incisure from the calamus,

Gubernaculum well developed, trough-shaped, about half of spicule length, with

serrated margins at its proximal end.

Type habitat and locality: Soil around the rhizosphere of grasses from a barren

field near village Lodha on Aligarh-Khair road.

Type specimens

Holotype female on slide Chiloplacus aligarhensis sp. n./1, ten females

and eleven males (paratypes) on slides Chiloplacus aligarhensis sp. n./2-11

deposited in the nematode collection of Department of Zoology, Aligarh Muslim

University, Aligarh.

Diagnosis and relationship

Chiloplacus aligarhensis sp. n. is characterized by the long body (0.75-

0.83 mm in females and 0.72-0.82 mm in males), lateral fields with five

incisures, labial probolae with well developed prongs, pharyngeal corpus 7-10

times isthmus length, ovary without flexures posterior to vulva, well developed,

offset spermatheca, long post-uterine sac (85-109 µm), female tail subcylindrical,

    68 

 

2-3 anal body diam. long, male tail conoid 45-52 µm long, spicules 30-35µm

long and gubernaculum about half of spicules length.

The new species resembles C. tenuis Rashid & Heyns, 1990, C. subtenuis

Rashid & Heyns, 1990 and C. magnus Rashid & Heyns, 1990 in general

morphometrics, shape and body size. However, from C. tenuis it can be

differentiated in the shape of labial probolae (prongs small and straight vs prongs

long and curved towards each other), longer pharyngeal corpus in females (155-

177µm vs 105-150µm), longer female tail (42-49µm vs 25-40µm. From C.

subtenuis it differs by slightly smaller pharynx in females (197-216µm vs 219-

240µm), males of C. subtenuis differs in having longer tail (45-52µm vs 38-

43µm), wider body diam. at cloaca (22-27µm vs 18-20µm), slightly larger c′

value (1.9-2.3 vs 1.6-1.8) and in the arrangement of genital papillae (three pre-

cloacal & five post-cloacal pairs vs four pre-cloacal & four post-cloacal pairs).

From C. magnus the new species differs by its smaller body size (753-829µm vs

883-1522µm), slightly posterior position of nerve ring and excretory pore (60-

66% & 60-72% vs 35-59% & 38-56% of the pharyngeal length respectively),

smaller pharynx (197-216 µm vs 222-289 µm in females and 191-209 µm vs 211-

245 µm in males), relatively smaller spermatheca (35-47 µm vs 48-99 µm),

smaller genital branch (73-113µm vs 143-218µm), smaller vulva-anus/tail ratio

(4.2-5.0 vs 5.2-8.0) and in having smaller testis (294-412µm vs 421-741µm).

    69 

 

Table 7: Measurements (in µm) of Chiloplacus aligarhensis sp. n. Mean and S.D. given in parenthesis

Characters Holotype

female Paratype females

(n= 10) Paratype males

(n= 11)

L 754 753-829 (786±28) 716-817 (772±33)

a 23 23.1-28.9 (26.5±2) 23-31 (26.5±2.2)

b 3.5 3.5-4.1 (3.8±0.2) 3.6-4.3 (3.9±0.2)

c 15.7 15.7-18.5 (16.8±0.9) 14.4-16.5 (15.5±0.7)

c´ 2.7 2-2.9 (2.5±0.3) 1.9-2.3 (2.1±0.1)

V 67 65.5-68 (67±0.5) --

Maximum body width 32 26.5-38.5 (30.5±3.5) 25.5-35 (29.5±3)

Lip width 10.5 10-11 (10.5±0.5) 10-11 (10.5±0.5)

Lip height 7 7-8 (7.5±0.5) 7-8 (7.5±0.5)

Length of stoma 11 11-12 (11.5±0.5) 10-12 (11±0.5)

Corpus 169 155-177 (163±7) 148-165 (156±7)

Isthmus 19 16.5-22 (18.5±1.5) 11.5-23.5 (17.5±3)

Basal bulb length 24.5 22.5-26.5 (24±1) 22.5-25.5 (24±1)

Pharynx 212.5 197-216 (205±6.5) 191-209 (198±7)

Excretory pore from ant. end 127 124-145 (136±6.5) 127-143 (135±5)

Nerve ring from ant. end 119 118-134 (127±5) 118-172 (140±20)

Dierid from ant. end 142 140-165 (152±7.5) 141-155 (148±5)

Basal bulb width 16.5 14.5-17.5 (16±1) 14-16.5 (15±1)

Anterior sac (Spermatheca) 39 34.5-47 (39.5±4.5) --

Genital branch 98 73-113 (88.5±12) --

Post-uterine branch 106 85-109 (95±8) --

VBD 30 25-38 (30.5±3.5) --

Vulva- anus distance 204 201-234 (215±12) --

Rectum/cloaca 21.5 21.5-23.5 (23±1) 29.5-33.5 (31.5±1.5)

Tail 48 42-49 (46.5±2.5) 45-52 (50±2)

ABD 17.5 16.5-23.5 (19.5±2) 22-27 (24±2)

Phasmids from anus 23.5 18.5-26 (23±2) --

Testis -- -- 294-412 (354±41)

Spicules -- -- 30-35 (33.5±2)

Gubernaculum -- -- 17-21 (19.5±1)

    70 

 

Fig. 13. Chiloplacus aligarhensis sp. n. A. Anterior region showing labial probolae, B. Anterior region showing stoma, C. Post-uterine sac, D. Uterus and spermatheca, E. Female posterior region, F. Male posterior region, G. Spicules and gubernaculum, H. Lateral lines (Scale bars = 20µm).

72

A B C

D

GF

E H

Genus Nothacrobeles Allen & Noffsinger, 1971

Diagnosis: Body length varying from 0.4 to 0.9 mm. Cuticle with broad annules,

with or without longitudinal striae or punctations. Lateral fields with two to four

incisures. Cephalic probolae in pairs, low, with or without serrate sculpture.

Labial probolae short to moderately long, slightly bifurcate and bordered with

small tines; outer rim or shaft with basal ridge. Amphids minute. Pharyngeal

corpus cylindrical. Female gonad cephaloboid. Tails in both sexes conical with

acute tip. Phasmids anterior to the lateral caudal papilla in males.

Nothacrobeles punctatus sp. n.

(Fig. 14, 15)

Measurements: In Table 8.

Females: Body robust, slightly ventrally curved after fixation. Cuticle simple,

transversely annulated, annuli 3-4 µm wide at midbody, with two rows of

punctuations. Lateral fields about 1/6th of the body diam. at midbody. Incisures

start about two stoma lengths from anterior end as two crenate lines and

differentiate into four lines at the level of isthmus. Outer incisures crenate, inner

ones smooth, areolation absent. Lateral fields extend up to the tail terminus.

Labial probolae 8-10 µm long, bifurcate for half their length, with a prominent

dentate basal ridge protruding outwards towards the cephalic probolae. Prongs

divergent and bifurcate, outer longer than the inner. Each prong with six

triangular tines on inner margin and eight on outer margin. Primary and

secondary axils deep with ‘U’ and ‘V’ shape respectively. Amphidial openings

minute, oval or round in shape. Stoma cephaloboid. Cheilostom wide, with

    73 

 

almost triangular rhabdia. Gymnostom narrower than cheilostom and as wide as

stegostom. Dorsal metarhabdion with a minute tooth. Pharyngeal corpus slightly

fusiform 3.5-4.0 times isthmus length. Corpus-isthmus junction with transverse

markings. Basal bulb spheroid, with well developed grinder. Nerve ring at 66-

78% of neck length, surrounding isthmus in anterior half. Excretory pore at the

level or just posterior to nerve ring. Hemizonid about two annules posterior to

excretory pore. Dierids in the isthmus region or at the level of basal bulb. Cardia

conoid, 5-7µm long, surrounded by intestinal tissue. Intestine with distinct wide

lumen throughout its length, intestinal cells well differentiated, rectangular in

shape.

Reproductive system mono-prodelphic, ovary reversed, without any

flexure. Oocytes arranged in a single row throughout. Oviduct short, tubular,

made of eight differentiated cells. Spermatheca well developed, usually longer

than the corresponding body diam., with few sperms. Uterus well developed,

about two to three times body diam. long. Uterus differentiated into a proximal

glandular part with narrow lumen and a swollen distal muscular part with wide

lumen. Distal and proximal parts of uterus separated by slight constriction. Post-

uterine sac less than one vulval body diam. in length. Vagina thick walled, about

1/3rd of vulval body diam. Vulva transverse, slit-like. Rectum slightly less than

one anal body diam. long, with three rectal glands. Tail conical, 2-3 anal-body

diam. long, with acute terminus. Phasmids located at less than one anal body

diam. posterior to anus.

Males: General morphology similar to females. Posture slightly straighter than

females but more ventrally curved posteriorly. Reproductive system monorchic,

    74 

 

testis reflexed ventrally, flexure on right side of intestine. Germinal zone with

two to three rows of spermatogonia, leading to the maturation zone with

spermatocytes and differentiated sperms at its distal end. Vas deferens with

numerous small round sperms. Ejaculatory duct wider than vas deferens with

narrow lumen. Tail conical, ventrally curved, terminating in an acute mucro.

Phasmids 1.3-1.5 anal body diam. posterior to anus. Genital papillae eight pairs;

two pairs subventral precloacal, one pair subventral adcloacal and five pairs

postcloacal. Of five postcloacal pairs, two pairs (one lateral and one subventral)

are located just posterior to phasmid and three pairs (one subdorsal, one

subventral and one lateral) near the tail tip. Spicules ventrally arcuate;

manubrium rounded; calamus cylindrical; lamina swollen near calamus.

Gubernaculum well developed, slightly bent anteriorly.

Type habitat and locality: Soil sample collected from a potato field, Shahrekord,

Iran

Type specimens

Holotype female on slide Nothacrobeles punctatus sp. n./1, three females

and six males (paratypes) on slides Nothacrobeles punctatus sp. n./1-4 deposited

in the nematode collection of Department of Zoology, Aligarh Muslim

University, Aligarh.

Diagnosis and relationships

Nothacrobeles punctatus sp. n. is characterized by having two rows of

punctations in each annule; bifurcate labial probolae, with divergent prongs;

spermatheca 28-50 µm long; post-uterine sac less than one vulval body diam.

    75 

 

long; female tail conical with acute terminus; phasmids at 21-32% of tail length;

spicules 45-49 µm long and gubernaculum 30-34 µm long.

The new species resembles Nothacrobeles subtilis Allen and Noffsinger,

1971 and N. maximus Allen and Noffsinger, 1971 in general morphometrics.

However, the new species differs from N. subtilis in cuticular punctations (with

punctations vs without punctations), more anterior position of phasmid (21-32%

vs near middle of tail) and in the presence of males. From N. maximus it can

easily be differentiated by the structure of cuticle (without longitudinal striations

vs with longitudinal striations), cuticular punctations (with punctations vs without

punctations), lateral fields (incisures crenate anterior to dierids then smooth

throughout the body length vs incisures crenate posterior to dierids) and in the

presence of males (males absent in N. maximus).

    76 

 

Table 8: Measurements (in µm) of Nothacrobeles punctatus sp.n. Mean and S.D. given in parenthesis

Characters Holotype

female Paratype females

(n= 3) Paratype males

(n= 6)

L 716 646-721 (683±35.0) 668-749 (710.5±28.0)

a 18.5 16.3-18.7 (17.6±1.0) 18.2-19.5 (18.9±0.4)

b 4.6 3.7-4.6 (4.2±0.3) 4.3-4.9 (4.6±0.2)

c 10 10.0-11.5 (10.9±0.6) 10.7-12.6 (11.5±0.6)

c’ 2.6 2.1-2.7 (2.5±0.3) 1.7-2.0 (1.9±0.1)

V 63 62-63 (62.5±0.5) --

Maximum body width 39 39-40 (38.9±0.5) 35-40 (37.5±1.5)

Lip width 17 15-17 (16.5±1.0) 16-17 (16.0±0.5)

Lip height 15 14-15 (14.5±0.5) 13-14 (13.5±0.8)

Length of stoma 13 10-18 (13.5±3.0) 13-15 (13.5±0.8))

Corpus 101 98-115 (105.0±6.5) 88-106 (99.5±6.0)

Isthmus 28 25-31 (28.0±2.0) 25-31 (27.5±2.0)

Basal bulb length 28 28-30 (28.5±1.0) 26-29 (27.5±1.2)

Pharynx 155 149-171 (160.5±9.0) 138-163 (152.5±8.5)

Excretory pore from ant. end 120 94-120 (110±10) 111-127 (118.5±5.0)

Nerve ring from ant. end 109 109-134 (115±11) 106-112 (109.5±2.5)

Dierid from ant. end 132.5 104-133 (123±11) 125-141 (132.5±5.0)

Cardia 7 5-7 (6.0±0.8) 5-7 (6.5±0.8)

Basal bulb width 21 21-22 (21.0±0.5) 20-22 (20.8±0.8)

Anterior sac (Spermatheca) 49.5 27.5-49.5 (42±9) --

Genital branch 100 96-100 (98.0±1.5) --

Post uterine branch 26.5 24-27 (24.5±1.0) --

VBD 34 34-38 (35.5±1.5) --

Vulva- anus distance 194 182-202 (192±7) --

Rectum 23 22-24 (23±1) --

Tail 71 56.5-71.5 (63.5±6.5) 57-66 (62.0±3.0)

ABD 26.5 24.5-26.5 (25.5±1.0) 30-34 (32.0±1.5)

Phasmids from anus 21 12-22 (17.5±4.0) 22-25 (23.0±1.5)

Testis -- -- 325-360 (341±12)

Spicules -- -- 45-49 (46.5±1.5)

Gubernaculum -- -- 30-32 (30.5±0.5)

    77 

 

H I

E

F

G

C

B DA

Fig. 15. Nothacrobeles punctatus sp. n. A. Anterior region showing stoma, B&C. Labial probolae, D. Vulval region showing post-uterine sac, E. Glandular part of uterus and spermatheca, F. Cuticular punctations, G. Female posterior region, H. Spicules and gubernaculum, I. Lateral lines (Scale bars = 20µm).

79

Genus Stegellata Thorne, 1938

Diagnosis: Body 0.3-0.7 mm long. Cuticle with transverse as well as longitudinal

striations, dividing each other to form small quadrate blocks. Lateral fields with

three to five incisures. Cephalic probolae simple, low. Labial probolae tuning

fork-shaped with thin shaft and U-like prongs. Pharyngeal corpus cylindrical.

Female genital organs cephaloboid. Female tail broadly, male tail narrowly

rounded.

Stegellata ophioglossa Andrassy, 1967

(Fig. 16)

Measurements: In Table 9.

Females: Body small, straight to slightly ventrally curved after fixation. Cuticle

with transverse and longitudinal striations, giving it a tessellated appearance.

Lateral fields distinct, occupying about 1/5th of the midbody diam.. Incisures

three, outer ones crenate. Lip region with six separate lips having rounded

margins. Labial probolae with wide base, 4-6µm long, bifurcate to about 1/3rd of

their length. Prongs divergent and equal in size, forming a semicircular arc.

Amphidial apertures round. Stoma cephaloboid, cheilostom wide, with small

ovoid rhabdia. Gymnostom narrower than cheilostom, and as wide as stegostom.

Metastegostom with a minute tooth like projection on dorsal rhabdia. Pharyngeal

corpus cylindrical, with distinct lumen, 3.3-4.5 times isthmus length. Corpus-

isthmus junction distinctly demarcated. Basal bulb ovoid or pear-shaped with

well a developed grinder. Nerve ring surrounding the base of corpus at 60-67% of

neck length. Excretory pore opposite the trailing end of nerve ring or at 62-71%

    80 

 

of neck length. Hemizonid just posterior to the excretory pore. Dierids at about

65-71% of neck length, lying in the anterior half of isthmus. Cardia short, conoid,

surrounded by intestinal tissue. Intestine with wide lumen at its anterior region.

Reproductive system mono-prodelphic. Ovary posteriorly directed

without any flexure. Oocytes arranged in two rows in the germinal zone and in a

single row in the proliferative zone. Oviduct short, tubular. Spermatheca less than

the corresponding body diam long, without sperms. Uterus simple, tube like,

undifferentiated. Post-uterine sac less than one vulval body diam. long. Vagina,

thick walled, with sclerotization. Vulva transverse, slit like. Rectum 1.2-1.6 anal

body diam. long. Tail cylindrical, 2.6-3.5 anal body diam. long, with

approximately 20 ventral annuli. Tail terminus flat. Phasmids one anal body

diam. posterior to anus.

Males: Not found.

Habitat and locality: Soil sample collected from the root zone of Sorghum sp.

from village Nohati, Madrak and from the root zone of Trifolium alexandrinum

from village Pisava, Chandaus, Aligarh.

Voucher specimens

17 females on slides Stegellata ophioglossa (N)/1-9 and 12 females on

slides Stegellata ophioglossa (P)/1-4 deposited in the nematode collection of

Department of Zoology, Aligarh Muslim University, Aligarh.

Remarks

S. ophioglossa is a terrestrial nematode, this species have previously been

recovered from sandy soils and dune sands. It is widely distributed and has been

described from Europe (Hungary, Italy), Asia (Uzbekistan, Mongolia), Africa

    81 

 

(Senegal) and South America (Venezuela). This is the first report of S.

ophioglossa from India, where, it was recovered from sandy as well as from

loamy soil. Despite the change in type of habitat the measurements and

descriptions of our specimens agree well with that of Stegellata ophioglossa

Andrassy, 1967. However slight variations from the original description were

observed in the height of labial probolae (4-6 µm vs 8-11 µm), relatively smaller

pharynx (96-112 µm vs 110-130 µm), smaller post-vulval uterine sac (less than

corresponding body diam. vs as long as or longer than corresponding body diam.)

    82 

 

Table 9: Measurements (in µm) of Stegellata ophioglossa Andrassy, 1967 Mean and S.D. given in parenthesis

Characters Females (n= 10)

Nohati population Females (n=12)

Pisava population

L 327 – 386 (347 ± 16) 341 – 409 (347 ± 16)

a 18.3 – 23 (21 ± 1.5) 19.2 – 22 (20.2 ± 0.8)

b 3.1 – 3.7 (3.4 ± 0.2) 3.2 – 3.7 (3.4 ± 0.2)

c 10.3 – 11.9 (11.1 ± 0.5) 10 – 11.4 (10.6 ± 0.5)

c’ 2.6 – 3.4 (3 ± 0.2) 2.9 – 3.7 (3.1 ± 0.2)

V 62 – 64.5 (63 ± 0.5) 61 – 63.5 (62 ± 0.5)

Maximum body width 15 – 18 (16.5 ± 1) 15.5 – 20 (18 ± 1)

Lip width 6 – 7 (6 ± 0.3) 6 – 7 (6.9 ± 0.3)

Length of stoma 9.0 9.0 – 10 (9.5 ± 0.5)

Corpus 66.5 – 72.5 (70 ± 2) 69.5 – 77 (72 ± 2)

Isthmus 14.5 – 21.5 (18 ± 1.5) 18.5 – 24.5 (22 ± 1.5)

Basal bulb length 14 – 16 (14.5± 0.5) 13 – 17 (14.5± 1)

Pharynx 96 – 112 (102.5 ± 4.5) 104 – 114 (108 ± 3)

Excretory pore from ant. end 67.5 – 73.5 (69 ± 1.5) 69.5 – 75 (73 ± 1.5)

Nerve ring from ant. end 61.5 – 68.5 (65.5 ± 2.5) 68 – 73 (70.5 ± 1.5)

Dierid from ant. end 72.5 – 79 (74.5 ± 2.5) 75 – 82 (78.5 ± 2)

Basal bulb width 9 – 12 (10 ± 0.5) 10 – 13 (11 ± 0.5)

Anterior sac (Spermatheca) 10 – 14 (12 ± 1.5) 7 – 10 (9 ± 1)

Genital branch 36.5 – 65.5 (45.5 ± 7.5) 32.5 – 48.5 (40 ± 4)

Post uterine branch 8 – 12 (10 ± 1.2) 8 – 11 (10 ± 1)

VBD 14 – 17 (15.5 ± 1) 15 – 19 (17 ± 1)

Vulva- anus distance 89 – 113 (98 ± 6.5) 92 – 119 (105 ± 7)

Rectum 13 – 15 (14 ± 0.5) 14 – 16 (15 ± 0.5)

Tail 28.5 –34.5 (31 ± 1.5) 30.5 –37.5 (35 ± 2)

ABD 9 – 12 (10.5 ± 1) 10 – 12 (11 ± 0.5)

Phasmids from anus 9 – 10 (9.5 ± 0.5) 7 – 15 (10.5 ± 2)

    83 

 

Genus Zeldia Thorne, 1937

Diagnosis: Body length between 0.6-1.0 mm. Cuticle annulated, annuli with or

without punctations or tessellation. Lateral fields with three to five incisures,

outer lines sometimes crenate. Lateral fields with or without areolations. Cephalic

probolae triangular, flap-like, low with setose projections. Labial probolae low

and rounded to elongate and shallowly to deeply bifurcate at one level; without

tines. Amphidial apertures elongate-oval. Lining of cheilostom without or with 1-

3 tooth-like processes. Pharyngeal corpus long and cylindrical. Intestine often

with prerectum. Postvulval uterine branch short or absent. Tails in both sexes

conoid, with pointed or finely rounded tip. Males rare or unknown in most

species.

Zeldia tridentata Allen and Noffsinger, 1972

(Fig.19, 20)

Measurements: In Table 10.

Females: Body robust, gradually tapering toward both the ends, straight or

slightly curved ventrally. Cuticle with transverse annules, 1.6 – 2 µm wide at the

pharynx base and midbody and 1.6 - 1.8 µm wide at tail. Each annule with two

rows of punctations. Lateral fields with three lines, outer ones crenate, areolated

in the pharyngeal region. Lip region 10-11 µm wide, 4-5µm high. Labial

probolae low, with round margins and shallow grooves. Primary axils deep, with

dentate guard processes. Amphidial apertures oval. Cheilostom with prominent

cylindrical walls, each cheilorhabdion associated with a structure having three

teeth. Gymnostom longer than cheilostom, metastegostom with a small tooth like

    85 

 

process on dorsal wall. Pharyngeal corpus cylindrical, 7.9-9.2 times isthmus

length. Isthmus shorter than basal bulb. Basal bulb ovoid, 21-26 x 18-21 µm,

with a grinder at its middle or slightly anterior. Cardia conoid, surrounded by

intestinal tissue. Intestine with wide lumen. Nerve ring at 59-66% of neck length,

surrounding the distal part of the corpus. Excretory pore just posterior to nerve

ring or one to two annules anterior to hemizonid. Deirids in the posterior region

of corpus, or at 67-78 % of neck length.

Reproductive system mono-prodelphic, ovary reversed, on right side of

intestine, with or without additional flexures posterior to vulva. Oocytes usually

arranged in a single row throughout the ovary length. Spermatheca scarcely

developed. Oviduct short. Uterus tubular, without any differentiation. Post-

uterine sac short, 0.3-0.5 times vulval body diam. long. Vagina with thick walls,

slightly anteriorly directed. Rectum 21-28 µm long. Tail elongate conoid, 4-5

anal body diam. long, with acute terminus. Phasmids 1-3 µm posterior to anus.

Male: Not found

Habitat and locality

Soil sample collected from an orchard of guava and cashew-nut near

Chilika lake, Puri, Orissa.

Voucher specimens

9 females on slides Zeldia tridentata/1-2 deposited in the nematode

collection of Department of Zoology, Aligarh Muslim University, Aligarh.

Remarks

Z. tridentata is distinguished from other species of the genus by the

presence of three teeth associated with each cheilorhabdion and the longer tail.

    86 

 

This species is widely distributed throughout the world and has been collected

from India, Jamaica, Philippine Islands, Srilanka, Taiwan, Thailand, and

Venezuela. Most of the species of the genus were collected from the soil or sand

around the root zone of different plants. The present population was also

collected from the sandy soil, around the root zone of Guava and Cashew Nut

plantations.

The measurements and descriptions of our specimens agree well with that

of Zeldia tridentata Allen & Noffsinger, 1972. However differences from

original population were found in the lateral fields (outer incisures crenated vs

smooth). Rashid et al., 1984, collected two females of this species from Itapebi,

Lombardia, Brazil, (Host: Theobroma cacao). They Illustrate and redescribed the

species and added more details to the original description. In Brazilian

population, cuticular punctations were not observed, however the punctations

have been reported in the original descriptions and are distinctly visible in our

population also. They also mentioned the ovary with a double flexure posterior to

vulva but in our population the specimens without any flexure were also found

along with the specimens having double flexure. In Brazilian population the

phasmid lies at about 5-6 annules posterior to anus however, in our population

phasmid lies just posterior to anus.

    87 

 

Table 10: Measurements (in µm) of Zeldia tridentata Allen and Noffsinger, 1972 Mean and S.D. given in parenthesis

Characters Females (n= 9)

L 635-779 (724±46)

a 19.0-23.5 (20.8±1.3)

b 3.7-4.0 (3.9±0.1)

c 8.5-9.0 (8.8±0.2)

c’ 4.1-4.9 (4.5±0.3)

V 61-62 (61.5±0.3)

Maximum body width 30.5-40.5 (35±3.0)

Lip width 10-11 (11±0.5)

Lip height 4-5 (4.5±0.5)

Length of stoma 15-17 (15.5±0.5)

Corpus 135.5-155.5 (147±6.5)

Isthmus 14-19 (16.5±1.5)

Basal bulb length 20-25.5 (23.5±1.5)

Pharynx 170-200 (187±9.0)

Excretory pore from ant. end 109-126.5 (121±5.5)

Nerve ring from ant. end 105-121.5 (116.5±5.5)

Dierid from ant. end 124-149 (137.5±9.0)

Cardia 5-6 (5±0.5)

Basal bulb width 18-21 (19±1)

Anterior sac (Spermatheca) 7-14 (10.5±2.5)

Genital branch 70-135 (9±21)

Post uterine branch 12-18 (13.5±2.0)

VBD 31.5-40.5 (35.5±3.5)

Vulva- anus distance 166-209 (194±14)

Rectum 21-28 (24.5±2.0)

Tail 73-87 (82.5±4.0)

ABD 16-21 (17.5±1.5)

Phasmids from anus 1-3 (2±0.7)

    88 

 

Superfamily Panagrolaimoidea Thorne, 1937

Diagnosis: Buccal cavity a single, fairly wide chamber, sometimes tending to

taper at its base. Metastom anisoglottoid and anisomorphic, narrower than

anterior part; telostom small and narrow. Pro-, meso- and telorhabdions usually

conspicuously thickened; cheilorhabdions sometimes thickened; metarhabdions

not thickened but metastom segments often bearing small teeth. Pharyngeal

corpus cylindrical or with swollen valveless median bulb; a narrow isthmus and a

basal bulb with grinders. Female genital organ prodelphic, ovary reflexed once,

usually well down into body; a short post-vulval sac sometimes present. Tip of

male gonad usually reflexed. Male supplements papilloid, arranged in pairs. No

bursa. Phasmids well discernible.

Type family: Panagrolaimidae Thorne, 1937

Other subfamilies: Alirhabditidae Suryawanshi, 1971

Brevibuccidae Paramonov, 1956

Family Panagrolaimidae Thorne, 1937

Diagnosis: Cuticle annulated, lateral fields distinct. Lip region practically without

probolae. Lips three or six, moderately developed.Amphids located on lateral

lips, small. Stoma consisting of the usual six elements, its anterior section

(cheilo- and gymnostom) spacious, stegostom tapering, metastom with a small

tooth-like projection. Pharynx consisting of corpus, isthmus and bulb. Female

genital organ prodelphic, reflexed part extending far behind vulva, rarely with a

simple flexure. Anterior separated portion of uterus serving as a spermatheca.

Postvulval uterine sac present. Males mostly abundant. Preanal genital papillae in

    90 

 

5-7 pairs. Tail conoid or elongate, in male generally shorter than in female.

Phasmids always distinct.

Type subfamily: Panagrolaiminae Thorne, 1937

Other subfamilies: Panagrellinae Andrassy, 1976

Tricephalobinae Andrassy, 1976

Turbatricinae Goodey, 1943

Baujardiinae Andrassy, 2005

Subfamily Tricephalobinae Andrassy, 1976

Diagnosis: Cuticle finely annulated, lateral fields distinct. Lip region without

probolae. Lips three or six, moderately developed. Cheliostom small and less

sclerotized, gymnostom well developed, stegostom tapering, Pharyngeal corpus

with bulb like median swelling. Terminal bulb very strong. Female genital organ

panagrolaimoid. Postvulval uterine sac present. Males mostly abundant. Genital

papillae 6-7 pairs. Tail uniformly conoid in female. Phasmids always distinct.

Type genus: Tricephalobus Steiner, 1936

Other genus: Halicephalobus timm, 1956

Genus Tricephalobus Steiner, 1936

Diagnosis: Body length between 0.5-1.0 mm. cuticle finely annulated, lateral

fields narrow. Head broad, continuous with body, lips three, separate. Cheilostom

short and not sclerotized, gymnostom well developed, stegostom funnel- shaped.

Pharyngeal corpus posteriorly swollen, bulb-like. Terminal bulb very strong.

Female genital organ panagrolaimoid, postvulval branch present. Both sexes

    91 

 

equally common. Spicules with narrowed proximal end, gubernaculum thin.

Genital papillae six or seven pairs. Tail conoid in female, and strongly narrowed

at posterior half in male, terminus sharp.

Tricephalobus quadripapilli sp.n.

(Fig.18, 19)

Measurements: In Table 11.

Females: Body slender, slightly ventrally curved after fixation. Cuticle simple,

with fine transverse annulations. Lateral fields narrow with two incisures,

occupying about 1/9th of the body diam. at midbody. Incisures arise at level of

median bulb as two smooth lines and extend up to the level of phasmids. Labial

probolae absent. Lips three, low and rounded, continuous with body contour.

Amphids indistinct. Stoma tubular, cheilostom with indistinct rhabdia.

Gymnostom slender, tube like, surrounded by a granular band like structure.

Stegostom as long as gymnostom, with slightly tapering dorsal wall. Pharyngeal

corpus posteriorly swollen into an oval median bulb, 2.7 – 3.7 times isthmus

length. Isthmus tubular. Basal bulb pyriform, with well developed grinder. Nerve

ring at 67-73% of neck length, surrounding isthmus at its middle. Excretory pore

at level of basal bulb. Dierids situated at the level of basal bulb or slightly

posterior to pharynx. Cardia short, conoid, surrounded by intestinal tissue.

Intestine with distinct wide lumen.

Reproductive system mono-prodelphic. Ovary reversed, without any

flexure, extending upto anus level. Oocytes arranged in multiple rows in germinal

zone and in a single row in maturation zone. Oviduct short, tubular, separated

    92 

 

from spermatheca by constriction. Spermatheca in continuation of uterus,

separated from it by slight constriction. Uterus well developed, differentiated into

a proximal glandular part and a distal muscular part with distinct lumen. Distal

part is twice as long as muscular part, both parts were separated by a constriction.

Post-uterine sac continuous with uterus, small, less than half vulval body diam. in

length. Vagina slightly anteriorly directed, about 1/3 - 1/2 of vulval body diam. in

depth. Vulva transverse, slit-like. Vulval lips slightly protruded. Rectum about

one anal body diam. long. Tail conical, 2.6-3.7 anal-body diam. long, with

narrowly rounded terminus. Phasmids 1.3-1.8 anal body diam. posterior to anus.

Males: Body slightly smaller than females. General morphology similar to that of

females. Reproductive system monarchic. Testis reflexed ventrally, flexure on

right side of intestine. Germinal zone with two to three rows of spermatogonia,

leading to the maturation zone with spermatocytes. Tail conical, ventrally curved,

strongly narrowed in its posterior half, terminating in a rounded tip. Phasmids

indistinct. Genital papillae four pairs; one subventral pair precloacal, situated at

level of spicule head, three pairs postcloacal. Of three postcloacal pairs, one

subventral pair is located at less than one anal body diam. posterior to cloacal

opening. Two pairs (one subventral and one subdorsal) located just anterior to the

beginning of narrower part of the tail. Spicules broad, with rounded manubrium,

broad calamus, ventrally arcuate lamina, with two longitudinal incisures from the

calamus. Spicule tip rounded. Gubernaculum small, less then half of spicules

length.

Type habitat and locality: Farm yard manure collected from a fallow field,

Poonch Jammu & Kashmir, India.

    93 

 

Type specimens

Holotype female on slide Tricephalobus quadripapilli sp. n./1; nine

females and ten males (paratypes) on slides Tricephalobus quadripapilli sp. n./2-

6, deposited in the nematode collection of Department of Zoology, Aligarh

Muslim University, Aligarh.

Diagnosis and relationship

Tricephalobus quadripapilli sp. n. is characterized by very fine transverse

annulations, a granular band around the gymnostom region, lateral fields with

two incisures, a well developed median bulb, ovary extending upto rectum

region, a constriction between glandular and muscular parts of uterus, sett off

spermatheca, broad spicules about 18-24 µm long, genital papillae four pairs and

tail with narrowed posterior half region.

The new species closely resembles T. steineri (Andrassy, 1952), Rühm,

1956 in general morphology and morphometrics. However, it can be

differentiated from T. steineri in having smaller post-uterine sac (less than half vs

one corresponding body diam. long), smaller tail (2.6-3.7 vs 4 ABD long in

females and 2.2-2.5 vs 3.5 ABD long in males), number of precloacal genital

papillae (one vs three).

    94 

 

Table 11: Measurements (in um) of Tricephalobus quadripapillii sp. n. Mean and S.D. given in parenthesis

Characters Holotype

female Paratype females

(n=9) Paratype males

(n=10)

L 491 434-517 (476±29) 391-473 (439±29)

a 17.7 17.5-19 (18.3±0.5) 18-20.5 (19.5±0.8)

b 5.3 4.6-5.8 (5.1±0.3) 4.2-5.1 (4.7±0.3)

c 10.8 9.7-12.8 (10.9±1.0) 10.5-12.5 (11.3±0.6)

c’ 3.1 2.6-3.7 (3.1±0.3) 2.2-2.5 (2.4±0.09)

V 61 58.5-62.5 (61±1.0) --

Maximum body width 27.5 23-29 (26±2.0) 20-25 (22.5±1.5)

Lip width 7 7-8 (7.3±0.5) 6-7 (6.7±0.4)

Length of Stoma 11 9-11 (10±0.5) 9-10 (9.2±0.5)

Corpus 56.5 54.5-59.5 (56.5±2) 49.5-60.5 (54.5±3.5)

Isthmus 19 16-22 (19±1.5) 17-29 (22.5±4)

Median bulb width 12 11-13 (12±0.5) 10-11 (10.5±0.5)

Basal bulb length 18 17-20 (18.5 ±1.0) 17-21 (18±1)

Basal bulb width 15 13-15 (14±0.5) 11-14 (12.5±1)

Pharynx 93 89-99 (94±2.5) 83-107 (94±7)

Excretory pore from anterior end 90 80-91 (85±4) 73.5-89 (81±5.5)

Nerve ring 67.5 63.5-69.5 (66.5±2) 57.5-74 (66±5)

Genital branch 113 90-127 (109±11.5) --

VBD 28 22.5-28.5 (26.5±1.5) --

Vulva- anus distance 144.5 122-164 (142±13) --

Rectum/cloaca 16 13-17 (15±1) 14-18 (16±1.5)

Tail 45.5 38.5-49.5 (44±3) 35.5-43.5(39±2.5)

ABD 15 12-15 (14±1) 15-18 (16.5±1)

Phasmids from anus 22 20-25 (22±1.5) --

Testis -- -- 196-261 (230±26)

Spicules -- -- 18-25 (21±2)

Gubernaculum -- -- 7-10 (8.5±1)

 

    95 

 

Fig. 19. Tricephalobus quadripapilli sp. n. A. Pharyngeal region, B. Anterior region showing stoma, C. Anterior region showing granular band around gymnstom, D. Lateral lines, E. Vulval region showing post-uterine sac, F. Female reproductive tract showing uterus, G. Female posterior region, H. Spicules and gubernaculum, I. Male posterior region (Scale bars = 20µm).

97

H G

F

I

A B

C

D

E

Family Brevibuccidae Paramonov, 1956

Diagnosis: Lips six, stoma relatively small, nearly twice as long as wide.

Pharyngeal corpus cylindrical or posteriorly swollen into a strong terminal bulb.

Female genital organ panagrolaimoid. Reflexed part of ovary not reaching to

vulva. Post-vulval uterine sac absent.

Type and only subfamily: Brevibuccinnae Paramonov, 1956.

Subfamily Brevibuccinae Paramonov, 1956

Diagnosis: Lips six, stoma relatively small, nearly twice as long as wide or

smaller or equal to lip region width. Pharyngeal corpus cylindrical or posteriorly

swollen. Reflexed part of ovary not reaching to vulva. Post-vulval uterine sac

absent. Both arms of spicules are equal or unequal, species often with unusually

long spicules.

Type genus: Brevibucca Goodey, 1935

Other genera: Cuticonema Sanwal, 1959

Plectonchus Fuchs, 1930

Genus Brevibucca Goodey, 1935

Diagnosis: Stoma short, expanding slightly at base, cheilostom and gymnostom

thick walled, forming half stoma depth; stegostom with an inwardly projecting

short tooth. No pharyngeal collar. Pharyngeal corpus cylindrical, isthmus short,

terminal bulb with grinder. Vulva posterior, gonad mono-prodelphic. Ovary

    98 

 

reversed not reaching vulval opening. A uninucleate gland cell on each side of

the uterus close to vagina. Testis outstretched. Spicules paired but of unequal

size. Gubernaculum present. Bursa absent. Genital papillae eight pairs.

Brevibucca postamphidia sp. n.

(Fig. 20, 21)

Measurements: In Table 12.

Females: Body slender, slightly arcuate upon fixation, tapering towards both

ends. Cuticle with fine transverse and longitudinal striations. Punctations fine,

sub-cuticular, transversely arranged. Lips separate, with minute hair like papillae.

Amphidial openings large, oval, post-labial at about 1/3rd of stoma length from

anterior end. Amphidial canal and fovea prominent. Cheilostom well developed,

slightly longer than wide, with thick cuticularised walls. Gymnostom short and

cuticularised. Stegostom anisomorphic. Dorsal wall provided with a tooth, each

subventrals with a smaller tooth. Pharyngeal corpus cylindrical, muscular, about

2.5 times isthmus length. Corpus isthmus junction distinct. Isthmus tubular. Basal

bulb ovoid, with well developed grinder and single haustrulum. Excretory pore

at level of corpus region, at about 38-43% of the pharyngeal length. Paired

excretory cells present just above basal bulb. Nerve ring encircling isthmus just

below corpus-isthmus junction, approximately at 62-66% of pharyngeal length.

Pharyngo-intestinal junction with well developed cardia consisting of three flaps.

Intestinal cells large, granular. Intestinal lumen variable in width.

    99 

 

Female reproductive system mono-prodelphic, ovary reflexed. Oviduct

narrow, joining ovary at a point slightly posterior to anterior tip. Spermatheca set

off by a slight dilation. Uterus undifferentiated, filled with embryonated eggs

and /or sperms. Up to ten eggs may be present at a time in the uterus. Vagina

strongly muscular, vaginal lumen unusually curved. Vulva a small transverse slit,

situated about 2.5 anal body diam. anterior to the anus. A uninucleate gland cell

on each side of the uterus close to vagina, connected by a duct to the uterus.

Post-uterine sac absent. Rectum 1.5-1.9 anal body diam. long, usually with wide

lumen. Tail extremely long filiform, 11-24 anal body diam., with fine tip.

Phasmidial openings distinct, 2-3 anal body diam. posterior to anus. Phasmidial

glands extending to just below the rectum.

Males: Body smaller than females, strongly curved ventrally in the posterior

region. Anterior end similar to that of females. Testis single, straight,

outstretched. Spicules dissimilar and of unequal size, larger one 27-30µm long

and smaller one 20-22μm long. Gubernaculum about half of larger spicule in

length, slightly curved proximally and with a sleeve distally. Genital papillae

eight pairs; three pre-cloacal (two subventrals and one lateral adcloacal), five

post-cloacal pairs. Of five postcloacal pairs, one subventral pair is located just

posterior to cloacal opening while three subventrals and one subdorsal pair are

closely grouped. This group is present just beyond phasmid, at the end of conoid

part of tail. Male tail with conoid part and a long filiform part.

Type habitat and locality: Decaying banana rhizome collected from Haldwani,

Uttarakhand.

    100 

 

Type specimens

Holotype female on slide Brevibucca postamphidia sp. n./1; twenty one

females and twelve males (paratypes) on slides Brevibucca postamphidia sp.

n./2-14, deposited in the nematode collection of Department of Zoology, Aligarh

Muslim University, Aligarh.

Diagnosis and relationship

Brevibucca postamphidia sp. n. is characterized by post-labial amphids

and large amphidial openings. Pharyngeal corpus about 2.5 times isthmus length.

Strongly muscular vagina with unusually curved vaginal lumen. Vulval slit about

2.5 anal body diam. to anus. A uninucleate gland cell on either side of uterus.

Long filiform female tail, about 11-24 anal body diam. in length (c=2.6-3.9).

Males with unequal and dissimilar spicules and eight genital papillae.

The new species closely resembles Brevibucca punctata Timm, 1960 in

general morphology and morphometric values in females but differs from it in

having smaller ‘c’ value in males (5.9-7.7 vs 8-10), structure of testis (outstreched

vs reflexed), size of gubernaculum (12-13 µm vs 18-22 µm) and in the position of

genital papillae (subdorsal pair anterior or almost at level of subventral group vs

subdorsal pair located posterior to subventral group).

    101 

 

Table 12: Measurements (in um) of Brevibucca postamphidia sp. n. Mean and S.D. given in parenthesis Characters Holotype

female Paratype females

(n=21) Paratype males

(n=12)

L 1446 1065-1679 (1380±199) 714-828 (766±35)

a 36.5 28.5-43.0 (35±4.5) 25-30 (27±1.5)

b 6.0 4.5-6.1(5.5±0.6) 3.9-4.2 (4±0.1)

c 3.2 2.6-3.9 (3.1±0.5) 5.9-7.7 (6.9±0.6)

L` 988 795-1073 (953±271) --

a’ 24.9 22.1-34.6 (24.8±27.6) --

b’ 4.2 3.2-4.4 (3.8±1.1) --

c′ 20.1 14.5-25.5 (20±2.8) 4.6-6.2 (5.5±0.5)

V 64 58-70 (63±3.5) --

Maximum body width 39.5 34.5-49.5 (39.5±4.5) 26-32.5 (28.5±2.0)

Lip width 12.8 11-13 (12.5±0.5) 10-11 (10.0±0.3)

Lip height 5 5-6 (5.1±0.4) 4-5 (4.2±0.4)

Stoma length 18 17-19 (18±0.5) 14-15 (14.5±0.5)

Stoma width 7 5-8 (5.5±1.5) 5-6 (5.2±0.4)

Corpus 148 146-173 (157±9.5) 107-122 (115±4.5)

Isthmus 60.5 57.5-74.5 (63±4.5) 47.5-55.5 (50±2)

Basal bulb length 28.5 26.5-32.5 (29.5 ±1.5) 23-26 (24.5±1.0)

Basal bulb width 22.5 21-28 (23±2) 17-18 (17.5±0.5)

pharynx 237.5 231-276 (249±14.5) 177-203 (189.5±6.5)

Excretory pore from anterior end 97 89-112 (99±7) 75-88 (81.5±4.0)

Nerve ring 148.5 148-179 (161±11) 113-129 (121±5)

Anal body diameter(ABD) 22.5 19-26 (22.5±2.0) 18-22 (20.5±1.0)

Genital branch 401 287-612 (412±95) --

Vulval body diameter (VBD) 32 26.5-37.5 (31.5±3.0) --

Vulval anus distance 63 44.5-63.5 (55±5.5) --

Testis -- -- 312-409 (342±26.5)

Rectum 43.5 33-44 (38.5±3.6) --

Tail 458 274-626 (452±94) 101-124 (112±8.0)

Phasmids from anus 59 47.5-64.5 (56-5.0) 25-30 (27±2.5)

Spicule (Small) -- -- 20-22 (20.5±0.8)

Spicule (Large) -- -- 26.5-29.5 (28.5±1)

Gubernaculum -- -- 12-13 (13±0.5)

    102 

 

Fig. 21. Brevibucca postamphidia sp. n. A-C. Anterior region showing parts of stoma, D. Anterior region showing amphid, E. Excretory cell, F. Part of gonad showing junction between oviduct and ovary, G. Female posterior region showing phasmid, H. Rectum, I. Female posterior region showing bivulvate condition, J. Anal opening, K, Anterior part of testes, L&M. Male posterior region showing spicules and gubernaculum

104

A B C D

LKFE

G H I J

M

Genus Plectonchus Fuchs, 1930

Diagnosis: Body slightly curved ventrally when heat-killed. Cuticle with delicate

annulations and fine transverse striae. Lateral fields with two ridges. Lip region

with six low lips slightly separated. Amphids circular. Stoma with a wide and

short cheilostom and gymnostom. Corpus cylindrical, without a distinction

between pro- and metacarpus. Isthmus long and narrow. Basal bulb rounded or

pyriform with distinct grinders. Nerve ring encircling the isthmus. Female

reproductive system monodelphic-prodelphic.

Plectonchus coptaxii sp. n.

(Fig. 22, 23)

Measurements: In Table 13.

Females: Body slender, straight to slightly ventrally curved after fixation,

tapering abruptly and curved strongly beyond vulva. Cuticle 2-3 µm thick,

hyaline, with very fine transverse striations. Lateral fields indistinct. Lips round

with short hair-like papillae. Amphidial apertures oval, post-labial in position.

Stoma very shallow, rhabdions fused and poorly developed, without any

armature. Pharynx panagrolaimoid. Pharyngeal corpus cylindrical, longer than

the combined length of isthmus and basal bulb. Corpus-isthmus junction very

gradual sometimes indistinct. Isthmus tubular, 0.45-0.6 times corpus length.

Basal bulb pyriform, with distinct grinder. Nerve ring encircling isthmus in its

anterior half, at 58-66% of the neck length. Excretory pore in the corpus region,

at 43-47 % of neck length. Dierids and hemizonid indistinct. Cardia conoid,

surrounded by intestinal tissue. Intestine with wide lumen.

    105 

 

Reproductive system monodelphic-prodelphic. Ovary on right side of

intestine, reversed, without flexure, never extending beyond vulva. Oocytes

arranged in two rows in the germinal zone and in single row in the maturation

zone. Oviduct short. Spermatheca small, less than the corresponding body diam.

in length, slightly offset and without sperms. Uterus tubular differentiated into a

proximal and a distal part with thin walls and distinct lumen. The lumen of distal

part usually filled with a single row of granular structures. Vagina short,

anteriorly directed. Vulval lips depressed to form a sunken vulva. Post-uterine

branch absent. A ventral body pore is present slightly posterior to vulva. Rectum

straight, 1.1-1.3 anal body diam. long. Tail elongate conoid, 3.1-4.2 anal body

diam. long, terminus pointed. Phasmids about one anal body diam. posterior to

anus, at 27-35% of tail length.

Males: Anterior end similar to that of females, habitus ventrally curved, more in

the posterior region. Cuticle thick and hyaline like that of females. Testis reflexed

ventrally, on right side of intestine. Spicules dissimilar, unequal and separate.

Right spicule slightly longer than left, straight, slender, with a bifid tip. Left

spicule more robust, arcuate, with fusiform lamina and without a bifid tip.

Gubernaculum heavily sclerotized, more than half of spicule length, strongly

curved at its distal end. Genital papillae eight pairs. Two subventral pairs

precloacal and six pairs postcloacal. Of six postcloacal pairs, two pairs (one

subventral and one lateral) are anterior to phasmid. Two subdorsal pairs and two

subventral pairs are located posterior to phasmid. Tail conoid with acute

terminus.

    106 

 

Type habitat and locality: Organic manure collected from an agricultural field,

Mendhar, Jammu and Kashmir, India.

Type specimens

Holotype female on slide Plectonchus coptaxii sp. n./1; nine females and

eight males (paratypes) on slides Plectonchus coptaxii sp. n./2-5 deposited in the

nematode collection of Department of Zoology, Aligarh Muslim University,

Aligarh.

Diagnosis and relationship

Plectonchus coptaxii sp. n. is characterized by a slender body; thick

cuticle with hyaline portion and fine transverse striations. Lips with hair like

papillae. Amphids oval, post labial in position. Stoma shallow without any

armature, rabdions fused. Ovary reversed, without flexure. Distal part of uterus

with a single row of granular structures. Ventral body pore posterior to vulva.

Female tail elongate conoid, with narrowly rounded terminus. Male tail conoid,

with acute terminus. Spicules symmetric or asymmetric. Gubernaculum strongly

sclerotized, more than half spicule length. Genital papillae eight pairs.

The new species closely resembles P. molgos Massey, 1974 but can be

differentiated by the structure of cuticle (with transverse striae vs without

transverse striae), larger ‘a’ value in females (24.5-31.9 vs 20.4-24.4), smaller ‘b’

value (4.0-4.4 vs 5.1-5.6 in females and 3.9-4.1 vs 4.2-4.9 in males), more

posteriorly located vulva (V= 78-81% vs V=75%), shape of vulval lips

(depressed vs protuberant), tail shape (without constriction vs constricted) and

number and arrangement of genital papillae (eight pairs vs six pairs).

    107 

 

P. coptaxii sp. n. differs from P. wyganti Massey, 1964, in having smaller

body (485-585 µm vs 700 µm in females and 472-517 µm vs 600 µm in males),

smaller ‘b’ value (4.0-4.4 vs 4.5 in females and 3.9-4.2 vs 4.6 in males), greater

‘c’ value in males (12-13 vs 10.8), number and arrangement of genital papillae

(eight pairs vs seven pairs).

    108 

 

Table 13: Measurements (in µm) of Plectonchus coptaxii sp. n. Mean and S.D. given in parenthesis

Characters Holotype

female Paratype females

(n=9) Paratype males

(n=8)

L 530 485-585(536±27.5) 472-517 (495±16)

a 28.2 24.5-31.9 (27.7±2.4) 24.4-32.6 (27.4±2.4)

b 4.1 4.0-4.35 (4.2±0.11) 3.9-4.2 (4±0.1)

c 11.9 9.8-13.0 (11.7±0.9) 12-13 (12.4±0.4)

c’ 3.5 3.1-4.2 (3.5±0.5) 2.1-2.7 (2.3±0.2)

V 79 78-81 (79.5±1.0) --

Maximum body width 19 18-21 (19.5±1.0) 16-21 (18±1.5)

Lip width 6.93 6.93 6.93

Length of Stoma 4 4-5 (4.5±0.5) 3-5 (3.5±0.5)

Corpus 70 64.5-77.5 (72±3.5) 61-71 (68±3)

Isthmus 40.5 31.5-43.5 (38±4) 34.5-46.5 (38.5±3.5)

Basal bulb length 17 16-19 (17.5 ±1.0) 16-17 (16.5±0.5)

Basal bulb width 11 11-12 (11.5±0.5) 9.8

Pharynx 127.5 113-137.5 (128±7) 121-126 (123±1.5)

Excretory pore from anterior end 55.5 54.5-64.5 (58.5±3) 49.5-57.5 (52±2.5)

Nerve ring from anterior end 74 72-88 (81±5) 70-77 (75.5±2.5)

Anterior sac (Spermatheca) 13 12-14 (13±1) --

Genital branch 201 185-248 (212±22) --

VBD 17 15-20 (17±1.5) --

Vulva – anus distance 66 56.5-74 (63.5±5.5) --

Rectum/cloaca 15 15-16 (15.2±0.5) 15-19 (17±1.5)

Tail 45 39.5-54.5 (46±4) 26-42.5 (38±5)

ABD 13 12-14 (13±0.5) 16.5-21 (17±1)

Phasmids from anus 15 14-16 (14.5±1.0) --

Testis -- -- 245-312 (280±24)

Spicules -- -- 19-21 (20±0.5)

Gubernaculum -- -- 12-16 (14±1.5)

 

    109 

 

Fig. 23. Plectonchus coptaxii sp. n. A. Pharyngeal region, B&C. Anterior region showing stoma, D. Anterior region showing amphidial aperture (dorsoventral), E. Female genital tract showing part of uterus, F. Female posterior region showing vulva and anus, G. Male posterior region showing spicules, H. Male posterior region showing gubernaculum (Scale bars = 20µm).

111

A B C D

G

H F

E

Summary

The present work represents a taxonomic study of the nematodes of suborder

Cephalobina. Samples of soil and organic manure were collected from various parts

of the country in addition some samples from old collections were also studied. The

nematodes were isolated by Cobb’s sieving and decantation and modified

Baermann’s funnel techniques. The extracted nematode samples were examined

under stereoscopic microscope. Nematodes were simultaneously killed and fixed in

hot FA (4:1). Later, the nematodes were transferred into glycerine-alcohol (5:95) and

kept in a desiccator for dehydration. Dehydrated nematodes were mounted in

anhydrous glycerine on glass slides using wax as sealing material. All Measurements

were made on specimens mounted in dehydrated glycerine with an ocular

micrometer. De Man’s (1884) formula was used to denote the dimensions of

nematodes. All morphological observations and drawings were made on Nikon 80i

DIC microscope and photographs were taken by ProgRes C3 camera mounted on

Olympus BX 50 DIC microscope.

In all, thirteen species belonging to eleven genera, falling under two

superfamilies, three families and four subfamilies has been described. Of these ten

species which are new to science have been described and illustrated in addition

three known species have also been described. Two known species are being

reported for the first time from India. The terminology used in the text to describe

the parts of stoma is of De Ley et al. (1995).

 

112

 

113

The systematic position of genera and species, described in the present study are

given below

I. Order

Rhabditida

II. Suborder

Cephalobina

III. Superfamilies

1. Cephaloboidea 2. Panagrolaimoidea

IV. Families

1. Cephalobidae

2. Panagrolaimidae

3. Brevibuccidae

V. Subfamilies

1. Cephalobinae

2. Acrobelinae

3. Tricephalobinae

4. Brevibuccinae

VI. Genera

1. Pseudacrobeles

2. Acrobeles

3. Acrobeloides

4. Cervidellus

5. Chiloplacus

6. Nothacrobeles

7. Stegellata

8. Zeldia

9. Tricephalobus

10. Brevibucca

11. Plectonchus

VII. Species

1. Pseudacrobeles ventricauda sp. n.

2. Pseudacrobeles mucronata sp. n.

3. Acrobeles mariannae

4. Acrobeloides glandulatus sp. n.

5. Cervidellus neoalutus sp. n.

6. Cervidellus minutus sp. n.

7. Chiloplacus aligarhensis sp. n.

8. Nothacrobeles punctatus sp. n.

9. Stegellata ophioglossa

10. Zeldia tridentata

11. Tricephalobus quadripapilli sp. n.

12. Brevibucca postamphidia sp. n.

13. Plectonchus coptaxii sp. n.

  114