Rev. Biol. Trop., 15 ( 1 ) : 185-19,. 1968

The exc retory sy stem in Ec hin ostome Ce rc ariae (Trematod a)

by

G P. Jain° and D. C. Yadav'

SEWELL (15) , RAo (13), 14), SRlVASTAVA (18), SRlVASTAVA and DUTTA (19) , SINGH (16), 17) and JAlN (9, 10) in India have solved some of Ihe life histories of certain trematodes and have descrihed many larval forms. They have emphasized Ihe value of the excretory system of Ihe larval flukes as a basis of description and group relationship_ The conservatism of Ihis system is again urged in the present pape! on the basis of investigations on echinostome cercariz. While the main purpose is to lay special emphasis on the excretory system, a brief -description of other organs is also made as a matter of record.

The cercari", were obtained from the liver of Indopl,,"oybis eXlIsl/U, col­lected from several ponds of Jabalpur in the months of July and October, 1966. The cercari., emerge between 9 and 12 A. M. and live about 24 hours in the labo­ratory. They swim and creep with comparatively great speed and characteristic­ally are nearIy equa.lly distributed throughout the container until they hecome spent and settle to the bottom. Saon after emergence, they altemately creep and swim in intervals of 2 ta 3 minutes. In bebaviour and general appearance, this cercaria agrees with the description of Cercaria mehy,,; (Faruqui) Jain, 1958.

THE CERCARIA

These cercari., (Fig_ 1) , designated as the offspring of redi." with a collar of 43 spines at the antenor end of the body, may be recognised by a pair of heavy colIecting tubules extending from the excretory bladder to the region of the pharynx. where they hecome constricted, reflex on themselves in triangular fashion and continue caudad to the posterior region of the body. This secondary

portion of the tubule in the posterior region .gain bends forward as a tertiary

>1' Departmeot of Zoology. Government Science College, Jabalpur (M. P.). India.

185

186 REVISTA DE BIOlOGIA TROPICAL

portien and continues to tbe regioo of the pharynx. This is a pattern of excretory system found in almost aLl echinostome cercarire. . . The body measures 0.160 X 0.112 mm. The tatI 13 larger than the body.

It measures 0.48 mm in length and tapers graduaUy towards the tipo The oral sucker is inclined ventral and measures 0.027 mm in diameter. The ventral sucker, which lie; behind tbe middle of tbe body, mea>ures 0.039 mm in diam­eter. Between the oral sucker and the pharynx is a slight prepharyngeal sphincter. Behind the pharynx is a long esophagus which normal!y forles just in front of

the ventral sucker. The caeCa reach to the subdistal region of the body, as in most echinostome larv". On either side of the esophagus, three pairs of gland celis are !he salivary glands. Their ducts pass forward and inwards to open by a series of small orífices around the anterior margin oE the oral aperture.

The primordium of genital organs is represented by a mass of smal! rounded granular ceUs in front of the excretory bladder. It probably represents the rudiments of ovary and uterus. Another mass of ceUs lies in front of the ventral sucker. 1t represents the vaginal orifice according to SEWELL (15) . The excrctory bladder, nonepithelialJ somewhat oval in shape, is situated in front of !he point of attachment of body and tail. The two main coUecting tubules, with membcanous walls, have a narrow calibre, then widen out and are filled with 5 to 6 globular refractile masses oi excretory material. These render tbem very prominent.

There are twelve pairs oE flame ceUs connected by minute capillaries wi!h the tertiary portion oE the tubule. The flame cell formula of the cercaria is 24 - 2 [ (2 + 3) + (2 + 4 + 1 ) ) . Such an arrangement of excretory tubules is wliformIy found in all echinostome cercaria!. The thin walled caudal excretary canal origioates on the dorsal 'Side of the bladder through ao aperture aod runs back tbrough tbe taiJ stem. It extends back up to the point where !he tail gives cise to the tapering cane. It cuns straight for the most part oí its course) but iD the posterior region it becomes somewhat wavy for a short distance. It !hen turns laterally to open below through a minute excretory pare to the exterior. There are no lateral branches given off E rom the caudal excretory canal. Flame cells are absent in !he tail.

DISCUSSION

LÜHE (12) for tbe first time presented a scheme of classification of the cercarüe On larval characters. LEBOUR (11) suggested that !he classification should be based on lbe nature of the parthinita from which !he cercaria develops. Later on S'WELL (15) proposed another classification for separating the ech­inostome cercarire ioto furee groups, 'Echinata', 'Echinatoides', and 'Coronata'. The comparison of Cercaria mehrai (Faruqui) with these groups shows that the system is conEusing. The fundamental pattern of tbe excretory tubules in the body of the echinostome cercari", is apparently and potentially inherent. The caudal 'excretory canal, oí all the various systems of the trematode anatomYJ seems most important for providing a basis of classification.

In consideration of tbe arrangement of !he caudal excretory canal, the

¡,/IN á YADAV, EXCRETORY SYSTEM IN ECHINOSTOME CERCARIAE 187

authors fee! justified in dlviding the echinostome cercada'! ioto three ilew groups: "Echinosolenata", "Echinobi,olenata" and "Echinopolysolenata".

la 'Echinosolenata' group, the caudal excretory canal is .ingle, median and unbranched throughout the entire course. In 'Echinobisolenata' tbe caudal excretory canal forks iato two branches. In 'Echinopolysoleaata' the caudal cx­cretory canal forks iato three branches, two lateral and Qne median which rons backwards in the tail.

Cercaria trholenata Faust, 1917 (fig. 2) ( 5 ) ; C. chisolenata Faust, 1918 (6) ; C. mebrai (Faruqui) Jain, 1958 (fig. 1) and C. pal rolris Chatterji, 1933 (3) are placed under tbe first new group 'Echinoso.lenata'. Tbe single caudal excretory canal mns tbroughout tbe taH to open to tbe exterior through a single minute excretory pore.

Tbe simplest condition of tbe caudal excreto'}' canal of tbe second aew group 'Echiaobisolenata' is seea in C. calenata Cawston, 1917 (fig. 3) (1). The caudal tube forks into two shoct lateral braach .. at tbe very end oE tbe tail so !hat two outlets are formed. It would not be out of place to mention here !hat a similar condition of excretory systern", as seen in C. c¿¡tena/a, also exists in am­phistome cere>!i.,. Next the point oE bifuxcatioa of the lateral branch .. from the caudal tube has shifted cephalad as se en iQ. Cercada conJlricta Faust, 1919 (fig. 4) (7). In Cercaria areuata Cawston, 1918 (fig. 5) ( 2 ) , C. Irivolvis Cort, 1915 (4) and C. ref/exa Cort, 1914, tbe caudal tube forks into two e!ongated lateral branche< SOon after in enters into the taH. The lateral branches then con­tinue distal and open to the exterior through two minute excretory pores in the subdistal regian oE the tail. In an advanced conditionl the excretory apertures at the stlbdistal region of tbe taiJ become occluded as seen in C. bif/exa Faust, 1917 (fig. 6) (5) . Cefcaria semndf!m Nicoll, 1906, C. bagu/ai Jain, 1960 (fig. 7) (10) and C. complexa Fatlst, 1919 (8) repíe<ents a condition in which tbe caudal tube divide< into two sbort lateral branches which opea to tbe exterior on ei!her side a little below tbe leve! oE !he bifurcation.

A condition oE a >lage ia advance to tbe second new grollp 'Echinobiso­lenata' cited aboye is expressed in t.�e caudal excretory system oE Cercaria (/Ctln­Ihosloma Faust, 1918 (Hg. 8) (6), C. indiCa! XII, C. indicdJ XX, C. indiCa! XXIII and C. indiedJ XLVIII Sewell, 1922 (15) placed llnder the tbird aew group 'Echinopolysolenata', where tbe caudal tube runs posteriorwards in the tai! and a pair of short lateral branches originate from abollt one eighth of the tube . . Tbey pass outwards to open on tbe dorsum.

Tbe autbors hold the view tbat tbe excretory system is tbe ollly chief feature of systematic importance in the c1assification oE the echinostcme cercari�.

TABLE 1

bnporlatJI bi% gical dala 01/ B�hit¡oJlome Cercari(/] � 00 00

Described Group and Spedes by Date Host LocaJity Partheníta.

1.. Echinosolenata Cercaría Il'iJolella/a Fanst 1917 PhyJd g)'rina Bittec Root River, Montana. Redia.

PJanorbh 'rillo/vis Cercaría chisoleflata Faust 1918 P h yM gyri na Pine Creek of Rack River, Illinois Redia. Cercaria mehrai Jaio 1958 IlIdol,/nllorbis 8X1IJIIIJ Jabalpur, Jndia. Redia. � (Faruqui) Jaio, 1958

Cercada pdlrutris Chatterji 1933 IlldoplaTlOl'bis exm/11J Allahabad, India. Redia. � 2. Echinobisolenata g

Cercaría ca/e na/a Cawston 1917 P/(/lWIÜS plel/er; Ducban, Natal, South Ardea. Redia. 5 Lymnaea nataJellsÍI ,... O PhysopsiI africall4 '"

Cercaría cOIIS/ricla Paust 1919 Pbpopsis africana Natal, South Afríea. Redia. ¡;: Cercaría arcualt1 Cawston Lymnea 'Jalalensis Natal, South Afeien. Redia.

.., 1918 '" O

Cerc:aril1 trivo/vis Cort 1915 PlmJOrbis trirJo/vis Normal School Pond, De Kalb; Redia. :!! drainage ditch, Ueban:!, Illinois g

Cercaria rel/exa! Cort 1914 Lymllttea "ef/exd Chicago, IlIinois, Redia.

Cercaria biflexa Faust 1917 Phy,ra gyrina Dittee Root Rivcr, Montana Redia.

Cerc:ada semndum NicolI 1906

Cercaría complexa Faust 1919 P/anorbis tf'ivolvis Urbana, Redi:l.

Ceullria bagl/laí ]ajn 1960 Lylllnaea /uleo/a Allahabad, India. Rcdia.

3. Echinopol ysolenata Ce"cdria aran/hos/oma Faust 1918 PlalJOrbis trivolvis Urbana. Redia.

PhySd gyrind Ce"carid, índiclC Xl( Sewell 1922 IlJdofJlaJJorbiJ eXflsJus N, Wynaad and neae Sultan's Redin,

Cercaría ;" dicae XX Scwell 1922 11ldoplanorbis exusttls Battery, Manntoddy, Redia.

Cercaria indicee XXIII Sewell 1922 llldoplrmorbis exmlus Redia.

Cercdria ilJdicte XLVIII Sewcll 1922 llld()plrworbis �XllItllI Redia.

lAIN (, YADAV, EXCRETORY SYSTEM IN ECHINOSTOME CERCARIAE 189

SUMMARY

Cercaria mehrai (Faruqui) is redescribed, wilh special reference to Ihe excretory 'ystem. The latter's importance is urged as a bas¡s on whicb fundamental group relationships of Ihe larval forms can be discavered. The echinastome cercarire are divided anew ioto three maio groups. The clase relationships of the echinostome cercari� is discussed.

RESUMEN

Se redescribe Cercaria mehrai (Faruqui), con mayor atención al sistema excretor. Se hace énfasis en la importancia de éste como base para la dasifi� cación de las formas larvarias, y se propone una nueva división de las cercarías equinostomas en tres grupos principales. Se comenta la estrecha relación exis­existente entre estas cercarias.

LITERATURE CITED

l. CAWSTON, F. G. 1917. The cercarire of Natal. J. Para.ritol., 3: 131-13�j,

2. CAWSTON, F. G. 1918. The possible intermediate hosts of Schistosoma in South Africa. J. Trop.

Med. Hyg., 21: 69-70.

3. CHA'ITER]C, R. C. 1933. Oa an echioostome ce!caria, C. paluSlris with notes on its life stocy.

Bull. Acad. Sci. U. P. Agra & Olldh, 2 : 193-201.

4. CORT, W. W. 1915. Sorne Noth American larval Trematodes. W. Biol. MOllogr., 1 : 447-532;

8 pI.

5. FAUST, E. C. 1917. Notes 00 the Cercarüe of the Bitter Root ValJey, Montana. J. ParaJito/.,

3: 105-123.

6. F AUST, E. C.

1918. Studies 00 1Iliniois Cercarix. J. ParaJitol" 4: 93-110.

7. FAUST, E. C. 1919. Notes 00 South Africao Cercari:e. J. PardJiJol., 5 : 164-175.

8. FAUST, E. C. 1919. lbe excretory system in Digenea. Biol. Bull., 36: 324.

9. ]AlN, G. P. 1958. 00 Cercaria mehrai Faruqui, 1930 with notes 00 its life history. Par�

litology, 48: 413-418.

190 RJ;VISTA DE BIOLOGIA TROPICAL

10. JAIN, G. P. 1960. A Oe'W ecruoostome cercaría. from Lymnaea /uleola with notes on its Jile

histo.ry, Proc. Nat. Aed. Sci. India, Section B, 30:' 47.·:50.

11. LBBOUR, M. V. 1911. A review of the British Marine cercarire. ParasilologYJ 3: 416-456.

12. lÜHE • . M. 1909. Parasitische Plattwürmer, .1 : Trematodes. Die Siisswasser FaJina Deutsch.

¡ .. d, Heft. 17: 215.

13. RAo, M. A. N. 1933. A pceliminary leport 00 the adult ttematode obtained frcm CercMite indiree

XXIII Sewel1, 1922. Ind. ¡. Veto 56., , : 29·;8.

14. RAo, M. A N. 1934. A comparative study of SchiItoJoma !pil1daliJ Montgomery, 1906 and SchiJ·

losoma nasalis n.s.p. llld J. Vel. Sá'J 4: 1·28.

15. SEWELL, R. B. S. 1922. Cercariz indicz. bul. J. Med. Res., 10: 19Q.-121.

16. SINGH, R. N. 1950. Studies on tbe egg & miracidium of Schislosoma indicum Montgomery

( 1906) . Proc. Nat. Acad. 56., India, 20: 9,·107.

17. SINGH. R. U. 1960. Studies on Fwcocercous La.cval Trematodes frcm India. Proc. Nat. Acc:J.

Sci., India, 30: 120-142.

18. SRlVASTAVA, H. D. 1944. A study oE the Jife history of Paramphúlomum of bovines in India. Pro(.

I"d. Sá. Gongr., Dclhi, 3: 113.

19. SRIVASTAVA, H. D. AND S. C. DUTrA 1951. Life rustory of S,hiIloJoma indi",m Montgomery, 1906 a common blood

fluke of Inclian unguJates. CUN'enl Sd., 20: 273.275.

Fjg. 1. Cercaria meh,ai (Farnqui). Abbreviations used - Caud. exc. c., caudal excretory canal; exc. bJ., excretory bladder; exc. p., exaetory pote; f. c., flame cell; m. exe. C., main excretor)' canal; O. S., oral sucker; V. S., ventral sucker.

lA/N {, YADAV: EXCRETORY SYSTEM IN ECHINOSTOME CERCARIAE 191

·/f.-*----Caud. f!xc .c.

:---....;· f!XC. p.

Fi g. l.

192 REVISTA. DE BIOLOGIA TROPICAL

Fig. 2. Cerct1ria /fÚo/enala, ventral vitw. X 1 50 Alter F,..UST ( 5 ) .

Fjg. , Cercaria caJellaJu, ventral view. X 170. After FAUST ( 7 ) .

FiJ;. 4. Cercar;" Caml,.;ct", ventral view. X 170. After FAUST ( 7 ) .

Fig. l . Cercaria a,.cIIP/a, ventral view. X 170. After FAUST (7) .

Fig. 6. Cercar;a bifleXtl, ventral view. X 105. After fAUST ( 5 ) .

Fi.'{. 7. Cercaria bagulai, ventral vie'>\'·. After JAIN ( t o ) .

Fig-. 8. e. acan/hQs/QlI1a ventraJ view. X 170. After FAUST (6) .

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IAIN " Y-iDAV .. EX=TO�Y SYSTEM JN ECHlNUSTOME CE�CARlAE 193

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