female (Wileman) (Lepidoptera, - J-STAGE

The Lepidopterological Society of Japan

NII-Electronic Library Service

The LepidopterologicalSociety of Japan

uttwh T>'ans. kpid Soc. Japan 52 (4): 313-331, September 2001

External morphology and musculature of the female of a specialized

psychid, Acanthopsyche nigraplaga (Wileman) (Lepidoptera, Psychidae)"

Mika SuGiMoToi} and Toyohei SAiGusA2)

i)Biosystematics Laboratory, Graduate School of Social and Cultural Studies, Kyushu Uniyersity,

Ropponmatsu, Fukuoka-shi, 810-8560 japan; e-mai[: [email protected]]Baikoen

2-7-l-402, Chuo-ku, Fukuoka-shi, 810-O035 Japan;e-mail: [email protected]

Abstract The integurnental morphology and musculature of the female ef Acanthopsyche

nigraplaga (Wileman) are presented together with brief notes on the bionomics ofthis species.

The relationship between the body structure and behaviour is discussed.

Key words External morphology, musculature, behaviour, Acanthopsyche nigraplaga,

Psychidae.

Introduction

The family Psychidae is well known fbr extrernely reduced external srmcture of the femalesand poculiar copulatery und ovipositing behaviours associated with the case-bearing habit oftheir larvae in spocialized forms. As to the generalized extremity ofpsychid evolution, there

are many primitive genera such as Diplodoma, Melasina, and Diysoctena, which have not only

well-developed legs but also functional wings for fiight, There are many intenmediate

evolutionary stages in the female body reduction and the specialization ofbehaviours betweenthese extremities, which have been classified by Saigusa (1962) in 4 evolutionary grades and2 subgrades which were called a-, fi-, 7- (71-, 72-), and 0-grade. Similarly Dierl (1973)divided the psychid females into 4 groups in respect of the female reduction, but hisclassificatjon is somewhat different from that of Saigusa (1962).

It is important to research detaited morphQlogy of the female body to understand the

evolution and phylogeny of the psychid moths. However, the only detailed merphological

work on the psychid female body structure is that done by Dierl (1964) on the genera Jlsyehe

(as Eumea) and Bniandia that belong to the 72-grade, As to the most specialized (S=grade,

rough illustrations and descriptions of external structure for taxonomic purposes were often

published, but no detailed merphology including musculature has been worked.

In this paper we describe the extemal morphology and musculature of the female of

Acanthpmyche nigrapinga (Wileman), one of the 6-grade psychids from Japan, compare

them with those of the above-mentioned genera assignable to the 72-subgrade, and discusstheir evolutionary and behaviQural significance,

' ContrjbutiQn from the Biosystematics Laboratory, Graduate School of Social and Cultural Studies,

Kyushu University (No.74). This study was in part supported by a Grant-in-Aid for JSPS

fe11owships from the Ministry of Education, Science, SpoJ.ts and Culture, Japaii (No. 1IO03364).




314 Mika SuaMoTo and Toyohei SAiGusA

Materials and methods

The adult females of Acanthopsyche nigrqpkrga used in this work were reared from pupaefield-collected in Fukuoka, Kyushu, and fixed and preserved as fo11ows. For the external

rnorpholegy, virgin females were fixed in Carnoy's solution for 1 day, and then preserved in

80% ethanol. For the study ofmusculature, living females which had already oviposited and

were shriveled were infiated by iniection ef 70% ethanol in their haemocoel, then fixed inCarnoy's solution for 1 day, and preserved in 80% ethanol.

For the ebservation of external structure, specimens preserved in ethanol and these macerated

in hot IO% KOH solution fbr 10minutes were used. For the observation ofmusculature,

inHated spocimens were dissected in 80% ethanol, and internal structures including musclesstained with eosin or Delafield's hematoxyline.

A stereoscopic binocular microscope (Olympus SZ 60) at magnifications up to × lgO wasused to observe both external structure and musculature. Terminology of muscles used inthis paper is mainly coincident with that used by Snodgrass (1935).

Results

1. External morphology

1) General rnorphology (Fig. 7)

The female of Acanthopsyche nigrapkiga is so-called vermifbrrn, almost cylindrical and is ofalmost the same thickness from the metathorax to the 7th abdominal segment. In the

specimens fixed with Carnoy's solution, the total length of body measured from the anterior

margin ofhead to the apex ofpapilla analis is 14- 16 mm, the height and the width of the 4th

abdominal segment are 3.0-3.3 mm and 3.1-3.3 mm, respectively.

The head is much reduced in size, O.65-O.70 mm high, O.75-O.83 mm wide, weakly sclerotized

and pale brown in colour, The thorax is reduced in size, weakly sclerotized and brownishon the median ponion of the dorsum of each segment. The total length of the therax

measured between the anterior margin of the prothorax and the posterior margin of themetathorax is 1.33-1.63 mm, 1/10 as long as body length. The appendages on the head andthorax are almost atrophied or wanting. The wings are completely wanting, and the legs arereduoed to minute projections.

The abdomen occupies most of her body, almost 9/10 as long as body length, cylindricat,straight and white in colour as its integument is almost entirely desclerotized except fbr weaksclerotization ofthe external genital structure. The 8th abdominal segment is much reduced

in size, and the apophysis anterioris is inyaginated, but very short. The papilla analis is shortand has a short apophysis posterioris.

2) Head (Figs 1-6)

The head is reduced both in size and exterflal structure, about 1/30 as long as body Iength,

The shape and arrangements of the structure ofthe head are more similar to those of the larvathan to the male adult. It is roughly spberical in frontal aspect, and hemispherical with more

or less produced frons in lateral aspect, O.39-O.43 mm long, O.75-O.83 mm wide, and O.65-O.70mm high, The anterior tentorial pits are located at the level of ventral l/3 of the head,separated from each ether by a distance of 1/2 of head width. The tentorium consists of a

pair of anterior tentorial arms and the tentorial bridge. The fbrmer are nearly as long as the



The LepidopterologicalSoclety ofJapan

External Morphology and Musculature of Fernale Acanthopsyche nigraplaga

)eg315

s

6

Figs 1-6. Acanthopsyche nigraplaga (Wileman), female. 1. Head and thorax, lateral aspect.

2. Ditto, ventral aspect. 3. Head and forelegs, anterior aspect, 4. Head, anterior

aspect. 5. Ditto, ventral aspect. 6. Ditto, latcral aspect. i-3 of one specimen; 4-6 of

another specimen.

distance between the tentorial pits, and run posteriorly parallel with each other. The

posterior portion of the anterior arm is connected with the posterior tentorial pit, which issituated in an almost rnembranous furrow along the posterior margin of the head.

The frontoclypeal region may be partly desclerotized, and bears many short setulae about O.08




316 Mika SuGiMoTo and Toyohei SAiGusA

mm. The antenna is located ventrolateral to the anterior tentorial pit rather close to theventral margin of the cranium. It is very short, O.03-O.16mm long, conical to elongate

conical in shape, and almost transparent. In well-developed cofldition, the antenna consists

of2 segments; the basal one bears 3minute setulae and a 1arge pit, and the apical one isslender and bears a minute setula at tip, In some specimens, the antenna is a conical

protuberance without the above-mentioned segmentation. An eye having norrnal cornea is

not recognized, but the cranial cuticula covering the blackish eye-spot pigmentation justposterior to the antennal base is desclerotized or transparent in various sizes and shapes.

The ventral membranous portion of the head is nearly half as wide as the head, and bearsreduced mouthparts. This membranous portion more or less expands to the ventral wall of

the cranium at the anterolateral corners. A pair ofslender sclerites on the dorsal wall ofthe

buccal cayity arises from lateral portions of the anterior margin of the frontoclypeal region,

and extends to the mouth opening.

The degeneration ofthe mouthparts varies somewhat in difierent individuals. The mandible

is represented by a minute flat weak sclerotization near the emarginated portion of the

ventrolateral margin of the cranium close to the antennal base, but it may be complete]yobliterated in some individuals. The maxi11a is represented by a crescent-shaped sclerite at

each side ofthe rnedian labial protuberance, and sometimes fused with the labial sclerite, Insome specimens, it is reduced to a minute conical protuberance that seems to represent themaxillary palpus and is surrounded by the maxi11ary sclerite. The labium is a]ways present,but its development varies in different individuals. The labium is a 1arge conical structure

O,1-O.25 mm high, Its basal portion is surrounded by a sclerotized ring, of which theanterior portion is expanded into a pair of sclerotizatiens on the ventral wall of the buccal

cavity, In a well-developed condition, the apical penion of the labium is weakly sclerotized

and bears a pair of minute projections, which seem to represent the labial palpi.

3) Thorax (Figs 1, 2)

The thorax is reduced in size. The dorsomedian ponion ofeach thoracic segment is weaklyscleretized, and they are fused with each ether leaving a transverse furrow or ridge betweenthem, The lengths of pro-, meso- and metanotum measured along the dorsomedian line areO,6-O.7 mm, O.8-1.0 mm, and O.6-O.9 rnm, respectively. The surface of the thoracic nota israther smooth, and their dorsal margin is almost evenly curved in lateral aspect. A pair ofminute denticles often appears at the anterior subdorsal portions of the pronotum. Thelateral areas of dorsum of each thoracic segment are membranous, unpigmented, and bearmany shert setulae. In a few individuals the lateral portions ofthe mesothoracic dorsum are

somewhat swellen to fbrm a setigerous swelling, which seems to represent the fbrewing. The

prothoracic spiracle is large, and situated at the top of a weak membranous protuberancesituated at the lateral portion of the prothorax. The mesothoracic spiracle is small, situated

at the lateral portion of the intersegmental area of the meso- and the metathorax.

The thoracic legs are greatly reduced, The length of the longest legs in each individual isO.15-O.23 mm. The leg is usually located on a membraneus conical swelling, In thewel!-developed condhion, the leg consists ef 2 short segments and a minute apical projection.Judging from the pattern of the articulation between the 2 segments, the basal one represents

the femur, the apical one the tibia, A small sclerite of various sizes and shapes is presentalong the ventrornedian line of the three thoracic segments. It is probably a vestige of the

furcisternum,




External Morphology and Musculature of Female Acanthopsyche nigraplaga 317

4) Abdomen (Figs7-9)The abdomen is well developed, cylindrical and occupies the posterior 9/10 of the femalebody. Its integument is almost transparent, but in the living individual the abdomen is whiteowi'ng to the whitish ovaries that occupy almost al1 the abdominal coelom. The reddish

brown central nervous system is also observable through the transparent integument, Theabdominal segrnents are clothed with long, whitish hairs, which, together with the coreth-

rogyne of the 7th segment, are usually rubbed off by the inner surface of the pupal exuviaewhen the female moves inside it,

i) First abdominal segment

The dorsum of the lst abdominal segment is weakly sclerotized and pale brown on itsdorsomedian portion. This lst abdominal tergum is fused anteriorly with the metanotumleaving a shallow transverse furrow or ridge.

ii) Second to 6th abdominal segrnents

The 2nd to 6th abdominal segments are cylindrical; each segment is nearly twice as long aswide, entirely membranous, and has no special structure. The 2nd segment is slightly shorterthan the others.

lii) Seventh abdominal segment

The 7th abdominal segment is nearly 1.5 times as long as the 6th, almost as wide as the latteron the anterior portion, and gently tapered to the 8th segment. The 7th segrnent bears thecorethrogyne, the so-ca!led anal hair tuft, consisting of dense long yellowish white hairs, butit is soon rubbed off as stated above.

iv) Eighth abdominal segment

The 8th abdominal segment is very short, O.8-O.9mm in length measured along the dor-somedian line. The 1arger part of the segment is sclerotized except for the dorsomedian

portion, which is rather widely desclerotized to be membranous or weakly sclerotized. The8th abdominal sclerite is longitudinally longest at the subdorsal portion, and graduallyshortened ventrally, and occupies the anterior 1/3 of the segment just anterior to the ostium

bursae at the ventromedian line. The s¢ lerite is pigmented with pale brown, and the colour

gradually fades posterierly. The apophysis anterioris is invaginated from the sublateral

ponion ofthe anterior margin ofthe selerite, It is very short and slender, O.2 mm long andbasally O.12 wide, shorter than 1/2 of the longitudinal length of the 8th abdominal sclerite

at the level ofthe apophysis, tapered to the pointed apex, The posterior margin ofthe 8thsegment rises as a transverse membranous ridge on the ventral 112. The ostium bursae issituated just anterier to the ridge, and is transversely oval in shape. It is entirely membra-

nous.v)

Ninth and 10th abdominal segments

The 9th and 10th abdominal segments compose together a papMa-like protuberance foroviposjting and excretory purpeses, which is commonly called the "oyipositor'7

in Le-

pidoptera systematics. This organ ¢ onsists of a pair of papillae anales composing its lateralwalls, and narrow dorsal and ventral membranous walls between the papillae, The papillaanalis is O,85-O.92 mm long, slightly wider than 112 long, narrow basally, gradually wideneddorsally to the middle, and has an almost straight ventral margin and rounded distal margin,

The anterodorsal 1/2 of the papilla is sclerotized and pigmented with pale brown, and its




3I8 Mika SuGIMoTo and Toyohei SAIGusA

Figs7-9. Acanthopsyche nigr:cu]laga (Wileman), female, 7. Whole insect, lateral aspect

(white area is membranous). 8. Apical ponion of abdomen, lateral aspect (white areas

are sclerotized portions). 9. Ditto, ventral aspect (white area is sclerotized portions).

posteroventral 1/2 is membra;)ous and bears many shert setulae O.02-O.06 mm long. The

middle of the anterior margjn of the papilla analis is invaginated into the coelom as the

apophysis posterioris, This apophysis is O.4-O.5 mm leng, nearly l/2 as long as the papillaproper, very slender, straight and directed anteriorly, It is more or Iess widened proxirnallyto the invaginated portion. A pair ofslender longitudinat stripes ofsclerotization are fbundon the ventral wall, which are homologous with the ventral apophysis of the primitivepsychids.

2. Musculature

The musculature ofthe head is not described in this paper. As the inside efthe craniurn ismostly occupied by the large brain and pharynx, it is not easy to discriminate fine fibers ofmusc1es, some of which will be present in the cranium, It is also assumed that no muscles

associated with head appendages are present, because these appendages are so extremely

reduoed or atrophied that they are not moved,

1) Prothorax (Fig, 10)

The prothorax has only one distinct muscle, the median internal dorsal muscle, In additjonto it, there are a few fine muscle fibers along the posterior intersegmental area below the




External Morphology and Musculatureof FemaleAcanthopsychenigraptaga 319

T2

Tl

d

dim

s's

Al A3

3

b･･･

,El,'--; ...,.iiti.i{..L=.::?i.l'--' demi

dem3

del2 dill dell

' '.i12gt[--.i,/1

'i'--ii='.'-'

---'g,Fi vel vill

l'ii'7S-i'tT.it7.tF.l=Ii4ii'..-!/.,ivem3vim2,,/fil.i:{-'ttr.--,ip`.-･-i=i;-=.t/l, vem2 ttviml lfi

-L"/L.' veml

Fig.10. Acanthopsyche nigraplaga (Wileman), female; rnusculature of thorax, lst and 3rd

abdominal segments. Tl: prothorax, T2: mesothorax,T3: metathorax, Al: lst abdom-

inal segment, A3: 3rd abdominal segment. Abbreviations of muscles correspond to

those in the text.

prothoracic spirac]e in some individuals. These fibers are not included in Fig. 10.

Median internal dorsal musele (dim): A short, rather broad, thin muscle arises from the

subdorsal portion of the anterior margin of the pronotum, runs longitudinally, and extends

to the posterior margin of the pronotum.

2) Mesothorax (Fig. 10)

The mesothorax has 2 bundles of strong median dorsal muscles and 2 fine lateral dorsalmuscles.

Median internal dorsal muscle (dim): A long, broad bundle-1i'ke muscle arises from thesubdorsal portion of the anterior margin of the mesonotum, runs obliquely ventrally and

extends to the sublateral portion of the posterior margin of the mesonotum,

Median externat dorsal muscle (dem): A long, broad, bundle-like muscle arises from thesubdorsal portion of the anterior margin of the mesonotum just ventral to the precedingmuscle, runs longitudinally, and extends to the posterior rnargin of the mesonotum a littledorsal to dim. It {s thicker than dim, Although thismuscle runs extemallyto thepreceding

muscle, it seems to be an internal rnuscle, as it extends between the intersegmental fblds,

Lateral external dorsal muscle (del): A fine muscle consisting of 1 to several fine fibers arisesfrom the middle of the sublateral portion of the mesonotum, runs posteroventrally, and

extends to the posterior margin of the mesonotum just ventral to the mesothoracic spiracle.

This muscle is absent in some individuals.




320 Mika SuGIMoTo and Toyohei SATGusA

Lateral internal dorsal muscle (dil): A short and fine muscle composed of one to several finefibers arises from the anterior submarginal area on the lateral portion of the dorsum, runs

longitudinally and ends near the preceding muscle. This muscle is absent in some individ-uals.

A few fine fibers of rnuscle may appear from the anterior margin just below the prothoracicspiracle in a few indivjduals. These are homologous with the lateral muscles of the

abdominal segments. They are not illustrated in Fig, 10.

3) Metathorax (Fig, 10)

Median internal dorsal muscle (did): This muscle is variable from a bundle Qf several fibers

to a narrow thin band. It originates from the subdorsal ponion of the anterior margin of

the metanotum, runs longitudinally, and extends to the subdorsal portion of its posteriorrnargln.

Lateral external dorsal muscle (del) and lateral internal dorsal muscle (dil): These muscles are

homologous with those in the mesothorax, and similar to them in their sizes and positions.

4) First abdominal segment (Fig. 10)

The lst abdominal segment has more muscles in comparison with the thoracic segments, butit lacks the strong median dorsal and median ventral muscles that are well developed in the

posterior abdominal segments. The development of the ventral muscles is weaker than thatof the dorsal muscles, This segment has 3 median lateral dorsal musc1es, 2 (or 3) medianinternal dorsal muscles, 2 lateral external rnuscles, 1 lateral internal muscle, 2-3 lateral intemalventral muscles and 2 median internal ventral muscles as fo11ows. The dorsal and ventral

muscles are al1 retractors that swell and shorten the segrnent, and the lateral muscles are

compressors that constrict the segment. The musculature of the 2nd abdominal segment issimilar to the lst abdominal segment, but the muscles are more developed, arid show the

intermediate condjtion between the lst and the 3rd abdominal segments,

Median externa] dorsal muscle 1 (deml): A narrow, thin muscle arises from the middle of

subdorsal portion of the segment and runs longitudinally, and is inserted on the posteriorintersegmental fbld. It is 1/2 as long as the segment,

Median external dorsal muscle 2 (dem2): A moderately broad, thin muscle arises just lateralto the preceding one, runs posteroventrally, and is inserted on the posterior intersegmentalfold.

Median external dorsal muscle 3 (dem3): A fairly broad, thin muscle originates from themiddle of the sublateral portien of the dorsum, runs posteTodorsally, and is wide!y insertedalong the posterior intersegmental fbld.

Median internal dorsal muscle 1 (diml): A narrow, thin muscle arises from the submarginal

portion of the anterior intersegmental fold, runs posteroventrally, and is inserted on the

posterior intersegmental fbld just ventral to the insenion ofdem3. This muscle is representedby several fine fibers or is completely obsolete in some individuals.

Median internal dorsal museles 2+3 (dim2+3): A broad, thin muscle extends between thesubdorsal portion of the anterior and posterior intersegmental foIds.

Lateral external dorsal muscle 1 (dell): A thin muscle arises from the anterior intersegmentalfold just lateral to the origin of the preceding muscle, runs posteroventrally, and extends tothe posterior intersegmental fold at the level of the spiracle, This muscle is variable in size





from a fairly broad one to one represented by several fine fibers,

Lateral external dorsal muscle 2 (de12): A rather narrow, thin muscle arises from the anterior

intersegrnental fold just ventral to the origin of the preceding muscle, runs ebliquely

posterodorsally, and inserts on the posterior intersegmental fold slightly lateral to the insertionof the median internal dorsal muscle 2+3, This and the preceding muscles are named hereas external, but they spread between the intersegmental fblds, so that they may be better

treated as internal,

Lateral internal dorsal rnuscie l (dill): A rather narrow, thin muscle arises on the lateral

portion of the anterior intersegmental fbld overlapping the insenion of the preceding muscle,runs longitudinally and ends on the posterior intersegmental fbld just dorsal to the lateralextemal dorsal muscle 1.

External lateral muscle (le): A very wide, long, mernbranous musc]e spreads between thelateral margins of dorsum and venter of the segment close to the integument, This is acompressor of the segment.

Internal lateral muscle (li): A rather short, narrow muscle spreading dorseventrally along the

anterior margin of the posterior intersegmental fold, It is a compressor of the segment.

Lateral internal ventral muscles 3-5 (vi13-5): This museie is a composite one homologouswith the lateral internal ventral muscles 3 to 5 in the 3rd abdominal segment, In the lstabdominal segment, these muscles are represented by a single narroxN, layer of muscle fibersextending between the subventral ponion of the anterior and posterior intersegmental folds.

Median internal ventral muscles 1-2 (viml-2): These muscles ai'ise from the subventral

ponion of the anterior intersegrnental fold, run longitudinally, and are inserted on the

posterior intersegrnental fbld. These muscles are thin, and may be separated into 2 groupsor completely obsolete in sorne individuals.

Median external ventral muscle (vem): A group of fine muscle fibers originates along the

subventral portion of the anterior intersegmental fold, runs obliquely rather posterolaterally,and is inserted along the posterior intersegmental fold,

5) Third abdominal segment (Fig. 10)

The basic pattern of musculature of the 3rd abdominal segrnent is simi]ar to that of the 1stabdominal segment, but the internal dorsal muscles are extremely developed, and the internalventral muscles are a]so well developed in the internal dorsal. This segment has 5 medianexternal dorsal musc]es, 3 median internal dorsal muscles, 2 lateral external dorsal muscles, llateral internal dorsal muscle, 1 external lateral muscle, 1 internal lateral muscle, 1 lateralexternal ventral musele, 3 lateral internal ventral musc1es, 3 median extemal ventral muscles,

and 2 median internal ventral muscles, The rnuseulatures of the 4th to 6th abdominal

segrnents are almost identical to that of the 3rd segment except fbr minor differences.

Median external dorsal muscle 1 (deml): A narrow, thin muscte arises from the middle of

subdorsal portion of the segrnent, runs longitudinally and is inserted on the posteriorintersegmental fold. It is 1/4 to 1/2 as long as the segment.

Medjan external dorsal muscle 2 (dem2): A muscle similar to deml arises from just lateralto the origin of deml, runs obliquely posterolaterally, and is inserted on the posteriorintersegmental fold. It is almost as iong as deml.

Median external dorsal muscle 3 (dem3): A narrow, thin muscle arises from the anterior




322 Mika SuaMoTo and Toyohei SATGusA

submarginal ponion of the subdorsal area of the segment, runs obliquely ventrolaterally

almost paralle] with dern2, and is inserted en the posterior intersegmental fold just lateral to

the insertion of dem2. It is slightly shorter than the segment.

Median external dorsal muscle 4 (dem4): A narrow or somewhat broad musele arises fromthe middle to posterior submarginal area ofthe segment, runs obliquely posterodorsally, and

ends in the posterier intersegmental fold between the insertions of dem2 and dem3. Thismusele is short, 1/5 to 1/3 as long as the segment.

Median external dorsal muscle 5 (dem5): A rather narrow, thin muscle arises from the

anterior submarginal area between subdorsal and lateral portions of the segment, runs

longitudinally, and is inserted on the posterior intersegmental fold lateral to the insenion of

dem3. This muscle is slightly shorter than the segment.

Median internal dorsal muscle 1 (djml): An extremely broad, thick muscle expands betweenthe anterior and posterior intersegmental fblds ofthe subdorsal area, and runs longitudinally.It overlaps deml to dem4, It may be incempletely divided longitudinally into 2 fibers.

Median intemal dorsal muscle 2 (d{m2): A moderately broad, thick muscle similar to dimlexpands between the anterier and the posterior intersegmental folds just lateral to diml, andruns longitudinally, It is half as wide as diml, and overlaps dem5.

Median internal dorsal muscle 3 (dim3): A narrow, thick muscle narrower than dim2expands between the anterior and posterior intersegmentat fblds just lateral to dim2, and runs

longitudinally. It is half as wide as dim2, and partially overlaps dem5 and the anterior

ponion of the next muscle.

Lateral external dorsal muscle 1 (dell): A narrow musele arises from the anterior submarginal

area just posterior to the origin of dim3, runs obliquely posteroventrally, and is inserted on

the posterior intersegrnental fold at the level of the spiracle, It is almost as long as the

segment.

Lateral external dorsal muscle 2 (de12): A narrow muscle similar to dell arises from theanterior submarginal area at the level ofthe spiracle, runs obliquely posterodorsally, and ends

on the posterior intersegmental fold near the insertion of dim3. Its insertion partly overlapsthe insenion of dim3. It is almost as long as dell.

Lateral intemal dorsal muscle 1 (dill): A narrow muscle arises from the anterior edge ofthe

anterior intersegrnental fold at the level of the spiracle, runs longitudinally, and is inserted on

the posterior edge efthe posterior intersegmental fbld, It overlaps the lateral portions ofdelland de12,

External 1ateral muscle (le): A very broad, extremely thin musc]e expands between the middleof the dorsal area of the segment and the lateral portion of the ventral area of the segment.It is s]ightly narrower than the length of the segment, runs transversely close or almosttouching the inner surface of the integument. It looks like a band consisting of fine fibersarranged longitudinally in a single layer.

Internal 1aterai muscle (li): A narrow, short, extremely thin musele arises from the posteriorintersegrnental fbld to a portion a little anterior to it and slightly ventral to the insertion of

dell, runs ventrally and is inserted on the area similar to its origin just dersal to the lateralinternal ventral muscle 3.

Median external ventral muscle 1 (veml): A narrow, short, thin muscle arises from the




External Morphology and Musculature of Female Acanthopsyche nigraptaga 323

ventromedian portion of the middle of the segment, runs posterolaterally, and is inserted onthe posterior intersegmental fold slightly lateral to the ventromedian line. It is 113-1/2 as

long as the segment.

Median external ventral muscle 2 (vem2): A narrow, thin musele arises from the middle of

the subventral portion of the segment, runs more or less obliquely posterolaterally, and isinserted en the posterior intersegmental fold. It is 112 to 2/3 as long as the segment

Median external ventral muscle 3 (vem3): This musele is similar to vem2, arises lateral to it,runs parallel with it, and ends on the posterior intersegmental fbld,

Median internal ventral muscle i (viml): A moderately broad muscle originates from theanterior margin or the submargin of the segment, runs longitudinally, and attaches on the

posterior intersegmental fold. It is almost as long as the segment

Median internal ventral muscle 2 (vim2): A muscle similar to viml runs closely lateral to and

parallel with it,

Lateral external ventral muscle (vel): A moderately broad, thin musele arises from the middle

portion of the ventrolateral area of the segment, runs obliquely posterodorsally, and ends on

the posterior intersegmental fbld. This is a short muscle, nearly 1/2 as long as the segment.

Lateral internal ventral muscle l (vill): A rather narrow muscle expands longitudinallybetween the anterior and posterior intersegmental fblds lateral to vim2, This muscle is nearly

as long as the segment.

Lateral internal ventral muscle 2 (vi12): A rnuscle similar to vill, which expands lateral to and

parallel with yill.

Lateral internal ventral muscle 3 (vi13): A broad muscle which expands most laterally among

lateral internal ventral muscles and runs longitudinally.

6) Seventh abdominal segment (Fig. 11)

This segment is fairly different in musculature from the preceding segments. The median

internal dorsal muscles are well developed, and act as the retractor of the 8th abdominal

tergum together with the lateral internal dorsal muscles, which are inserted on the tip of the

short apophysis anterioris. The internal ventral muscles are apparently much more reduced

in number and in thickness than in the preceding segments. The reduction of the external

dorsal and the external ventral rnuscles is also prominent in thjs segment. The lateral

muscles are more diflerentiated than in the proceding segments. This segment has 1 median

external dorsal musele, 3 median internal dorsal rnuscles, 2 lateral intemal dorsal muscles, 1broad extemaMateral muscle together with some transverse and longitudinal layers of the

lateral muscle group, 1 internal lateral musele, 1 lateral internal ventral muscle, 1 median

external ventral muscle and 1 median internal ventral musc]e.

Median external dorsal muscle (dem): A narrow bundle of muscle originates on the middle

portion of subdersal area of the segment, runs longitudinally, and ends at the subdorsal

portion ofthe anterior margin of the 8th abdominal tergum. It is nearly 1!2 as long as the

segment.

Median internal dorsal muscle 1 (diml): A slender muscie arises frern the anterior submar-

ginai area of the dorsal portion of the segment, runs longitudinally and is inserted on the

anterior margin of the 8th tergum,



The LepidopterologicalSociety ofJapan

324 Mika SuGiMoTo and ToyoheiSAIGUSA

li

Fig.11. Acanthopsyche abdomen.

analis.

Median internal dorsalanterior submarginal

the subdorsal portion

Median internal dorsal muscle 3

parallel with dim2.

Lateral internal dorsalintersegmental foldbocomes finer posteriQrlynally.Lateral

internal dorsalruns parallel with itnarrower than dill

Internai lateral muscle

fibers arises on the

is inserted Dn the subventral portion ofthe fbldof the 6th abdominal segment situated

recognized on the

Extemal lateral muscle (le)of the dorsal area

It occupies the anterior

inner surface of thelongitudinally, Theexternallateral

9+10

nigraplaga (Wileman), female; musculature of posterior portion of

A7: 7th abdominal segment, A8: 8th abdominal segment, A9+10: papillaAbbreviations of muscles correspond to those in the text,

muscle 2 (dim2): A very bread, thick muscle expands from the

area of the subdersal ponion of the segment to the anterior margin of' of the 8th tergum. It runs longitudinally,

(dim3): A muscle similar to dim2 in size runs 1ateral to and

lts insertion is dorsal to the base of the apophysis anterjoris.

muscle 1 (dill): A basally broad musole originates from the anterior

and is inserted on the apex of the apophysis anterioris, This muscle

and almost tenden-like at the insertion. It runs almost longitudi-

muscle 2 (di12): A muscle arises slightly laterally (ventrally) to dill,

, and is inserted on the apex ofthe apephysis anterioris. This rnuscle is

(li): A moderately broad, thin band consisting of a layer of muscle

anterior intersegmental fbld at the level ofthe spiracle, runs ventrally and

. This muscle is almost continuous with that

anterior to this muscle, No lateral internal muscle is

posterior intersegmental fold.

: A very broad, extremely thin muscle expands between the middle

of the segment and the lateral portion of the ventral area of the segment,

' 1/2 of the segment, runs transversely close to or almost touching the

integument. Jt is a single layer consisting of fine fibers arranged

muscle also includes a narrow band of muscle transver-




External Morphology and Musculature of Female Acanthopsyche nigrqplaga 32s

sely arranged on the posterior I/2 of the segment. This muscle is thin on the dorsal portionand somewhat dilates on the ventral portion, A fine bundle arises from the anterior

submarginal area close to the ventral insertion ofle, and is inserted on the middle ofthe upper

lateral portion of the segment. This muscle is independent from le, In addition to thislayer, there are several barids of thin layers of longitudinal muscles, which occupy the

posterior 1/2 of the lateral area of the segment,

Median external yentTal muscle (vem): A moderately broad, thin muscle arises from themiddle portion ofthe subventral area ofthe segment, runs longitudinally and attaches on the

anterior margin of the 8th abdominal sternum.

Lateral internal ventral muscle (vil): An anteriorly broad layer of fibers arises from theanterior intersegmental fold and extends to the subventra! area ofthe anterior margin ofthe

8th abdominal sternum.

Median internal ventral muscle (vim): An anteriorly broad layer of fibers arises from theventral area ef the anterior intersegmental fbld and extends to the ventral portion of theanterior margin of the 8th sternum,

7) Eighth abdominal segment (Fig. 11)

This is a small segment, and has a selerotized ring composed of tergum and sternum, Mostof the museles of this segment attach on the ring, and control the movement of the papillaanalis. The segment has 1 elevator of the papilla, 1 retractor ofthe papilla, 1-2 protractorsof the papilla, 1 adductor of the papilla, and 1 fiexor of the papilla.

Elevator of papilla analis (elpa): A narrow muscle arises from the subdorsal ponion of the

anterior margin of the 8th abdominal tergum and extends to the dorsal portion of the baseof the apophysis posterioris.

Retractor of papilla analis (repa): A short narrow bundle originates on the 8th abdominal

tergum just posterior to the base of the apophysis anterioris, and is inserted on the tip oftheapophysis posterioris.

Protractor(s) of papilla analis (prpa): A group of short rnuscles originates on the lateral

portion ofthe middle ofthe dorsal part ofthe 8th abdominal segment, and is inserted on the

tip of the apophysis posterioris.

Adductor of papilla analis (adpa): A narrow muscle arises from the tip of the apophysis

posterioris, runs close to the apophysis and is inserted on the basal portion of the papillaanalis close to the base ofthe papilla This muscle seems to act as the adductor efthepapi11a

analis.Flexor

of papilla analis (flpa): A fairly broad muscle arises from the anterior margin of the

subventral portion of the 8th abdominal sternum, and is inserted on the anteroventral portionof the papilla analis.

8) Papilla analis (Fig, 11)

The papilla analis has at least 2 intrinsic muscles. One of them is a longitudinal compressor

of longitudinally arranged muscle fibers arising from the dorsoproximal portion of the papillaand is inserted on the dorsodistal portion ofthe papilla, The other is a layer of transversely

arranged fibers occupying the 1ateral wall of the papilla analis.




326 Mika SuaMoTo and Toyohei SAiGusA

3. Notes on some behaviours having morphologica] significance

In this section, we give brief notes based on our observations on some behaviours that have

a close relationship with the function of the structure and musculature described and

illustrated in the preceding sections. These notes are considered in the discussion section.

1) General bionomics

Acanth(zasyche nigraplaga is univoltine, and hibernates as the egg, which hatches in spring.The larva gradually grows from spring to early autumn. The mature larva fixes the case to

tree trunks, fences, poles, walls, etc,, and pupates. The adult appears in autumn (areundmiddle October in Fukuoka, soutbern Japan). This species inhabits herbaceous vegetation.The larva is herbivorous, and feeds on living, dead, and somewhat decayed leaves and stems

ofvarious herbaceous plants in captivity. Seino (1976) reared larvae with leaves ofDiaspyros

kaki, a woody plant in the Ebenaceae. The larva makes a slender cylindrical case, vLThich

is slightly tapered pesteriorly and covered with short pieces of grass stem arranged longitudi-nally.

2) Emergence

When the male emerges, the male pupa protrudes the anterior 1/2 of the body from the

posterior opening of the pupation case, then ecloses. When the adult female emerges, she

pushes the anterior portion of her pupal cuticula breaks it along the cervical margin of the

head, the dorsomedian line ofthe thorax, and along the 1ateral margins ofthe thoracic nota,

As the intersegmentat membrane of the pupal cuticle between the metathorax and the lst

abdominal segment is very soft, and consequently this membrane may also be breken, thefemale adult can easily crawl eut from the pupal exuviae in the larval case.

3) Calling behaviour

After emergence the female adult often exposes the anterior portion of her body from the

posterior opening of the pupation case, which is considered the posture for calling the males.She also returns back into the case and the pupal exuviae. This movement is operated by

the vermiculation of her abdomen.

4) Egg-laying

The female lays eggs inside the pupal exuviae. The inner surface ofthe exuviae is lined withflui]fy hairs and scales rubbed off from the fernale integument, The female fills the exuviae

with eggs from its bottem to a position corresponding to the anterior portion ofthe abdomen,

as the female moves her ovipositor along any plane, although it is short and papilla-like.After she has laid all her eggs inside the pupal exuviae, she comes out from the pupation case,

and drops on the ground. She also moves by vermiculation from the case, and this

movement still continues after she drops onto the ground, In the vermiculation, she

constricts a part ofher abdomen (for a length of 1-2 abdominal segments), This constrictedring suocessi'vely moves forwards er backwards.

5) Retraction of head

When the female adult is disturbed by touching her body, she strongly retracts her headtowards the prothorax. If she retracts her head inside the pupal exuviae, she may plug theopening of the exuviae with the sclerotized thoracic nota. This may act as a defense against

any intruder,




ExteTnal Morphelogy and Musculature of Female Acanthopsyche nigraplaga 327

Discussion

1. Relationship between external morphology and behaviour

It is well known that the females of psychids belonging to the 6-grade are vermiform in bodyshape without most external structures. T.he degree of the degeneration of the structure issomewhat variable among species of the 0-grade, Some of the species most advanced inreduction belong to the genera Eumeta (Yano, 1958; Entwistle, 1963; Saigusa, 1981),Mahasena (Seino, 1977; Sugawara et aL, 1963), StTrglocynbasia (Sugimoto et Saigusa, 2oo1),etc. In these genera, the head often completely lacks any appendicuLar rudiments includingantennae and mouthparts, and also compound eyes and ocelli. In the latter genus, the thoraxis also much reduced and it Iacks any projection ofthoracic legs, The female ofAcanthopE},-che nigraplaga represents one of the most generalized states in the 6-grade psychids, as it stillretains vestiges of antennae, components of mouthparts, and thoracic legs. However, thefemale of this species has no functional legs, which would enable her to completely protrudeoutside of the pupation case. Therefbre the female mainly stays in the pupal exuviae in the

pupatlon case.

The cranium of the females in 6-grade psychids is usually smooth on its surface, though insome species, such as in the genus Eumeta, the female cranium has a pair of strongly

sclerotized processes (Yano, 1958; Entwistle, 1963; Saigusa, 1981), and the females completely br.eak the anterior ponion of the pupal cuticle, so that the females stay in the exuviae,

which lose the head+thorax region. In A. nigraplaga, the female cranium is smooth on itssurface, and it has no sclerotized processes to destroy the anterior portion ofthe pupal cuticle,

therefbre the head+thorax region is not separated from the abdominal part of the exuvjae,

which has the usual break 1ines along the dorsomedian Iine ofthe thorax and the line betweenthe posterior portion of the head and the thorax,

ln the female of A. nigTaplaga, almost all the body surface except fbr the weakly sclerotized

cranium and thoracic dorsum is membranous and very soft; its cuticula is very thin. Thiscondition is quite exceptional in Lepjdoptera, of which most species have sclerotized terga

and sterna on the abdomen, The extensive membranization of the female body wall in A.nigraplaga is closely associated with behaviour: i e, the female usually stays in the sclerotized

pupal exuviae that are also concealed in the hard pupation case. The soft-skinned femalebody is wetl protected by the pupal exuviae and the pupation case,

The membranized body wal1 of the female A. nigrapinga is also effective fbr the venmiculationmovement in the pupal exuviae and the pupatien case and for the protrusion ofthe anterior

part of her body from the posterior opening of the pupation case to ca]1 her mates. Inaddition to the softening of the body wal1, the scales rubbed off from the female body are

considered to act as antifriction between the inner surface of the exuviae and the soft

jntegument during the vermiculation movement in the exuviae. The fluffy silk layer spun bythe larvae in the posterior portion inside the larval case before pupation also act as antifric-

tion during the femate movement outside the pupal exuviae in the pupation case,

In the female of A, nigraplaga, the cranium and dorsal ponions of the thorax and of the lstabdeminal segment are sclerotized, These parts of the body face the outside of the exuvjae,when the female stays in it. In this conditien, the female usua!ly pulls her head towards herthoracic venter when she is disturbed, and the pupal exuviae seem to be plugged by hersclerotized cranium and thoracic terga.

Jn the females of the 6-grade psychids, the 7th abdominal segrnent bears the corethrogyne,




328 Mika SuGiMoTo and Toyehei SAiausA

anal hair tuft, which consists either of longish hairs or of powder-like minute scales; the 8th

segment is smal1 and has a weakly sclerotized ring composed by the tergum and the sternum

fused with each other, of which the tergum has the apophysis anterioris represented by a blunt

projection; the papilla analis is short and soft, with a very short apophysis posterioris, On

the other hand, in more generalized grades ofthe psychid evolution, the females have elongate

apophyses anteriores and apophyses posteriores, and long, slender papillae anales, They use

these elongate structures to lay eggs inside crevices ofthe substratum, in the pupauon case, or

even in the pupal exuviae in the pupation case, In A. nigraplaga females, the basic structure

of the female terminalia is the same as those in the d-grade psychids. They lay eggs in the

pupal exuviae, which is fi11ed with eggs from the bottom, and hairs from the corethrogyne

mixed with the eggs, The short female terminalia are quite functjonal fbr such egg-laying

behaviour.

The hairs or scales of the corethrogyne are used to protect the eggs in various ways in the

Psychidae. The females ofspecies mere generalized than those ofthe a-grade have elongate,

extensible "ovipositors".

They can rub the hairs using it and the 8th abdomina] stemum,

and mix the hairs with eggs which are laid either in crevices of the stratum, among moss and

lichen, the pupal exuviae in the pupation case or the pupation case (Tutt, 1900; Saigusa, 1962,

1972), In Eumeta vahegata, the female retains the powder-like hairs of the corethrogyne

until she lays all the eggs, and then $he rubs thehairs against the surface ef the egg-mass inthe pupal exuviae making a thick hair-plug (Saigusa, 1981), In A. nigraplaga the hajrs ofthecorethrogyne are mostly rubbed off prebably by her vermiculation soon after she emerges, and

hairs are scattered in the pupal exuviae. Consequently the hairs are naturally mixed with

eggs, when she lays her eggs.

The enormeusly developed abdomen that occupies 9/10 the length of the body is almost fi11edwith ovaries having numerous mature eggs in the female of A. nigraplaga. The ovarioles

spread to the thoracic cavity close to the head. As the female does not take fbod, the

alimentary canal is quite shriveled and its wall becomes very thin. No fat tissue is recogniz-

able in the haemocoel ofher body. The paits ofthe female reproductive organs, such as thebursa copulatrix, the spermatheca and the accessory glands are greatly atrophied. Therefore,

the female maximizes the space for the ovaries in her body.

2, Relationship between musculature and behaviour

The muscular system is as important as the external structure fbr discussion of behaviourbased on functional morphology. In the A. nigraplaga female, the muscular system is greatlyreduced especially in the head and thoracic segments, but it has an important function for her

calling, mating, and egg-laying activities.

In the thorax most of the muscles associated with fiight and walking are lost in the femaleA. nigraplicrga. But the longitudinal dersal muscles including the median extemal and

internal dorsal muscles are still present in the pro- and mesothorax in rather well-developed

condition. In the winged psychids these muscles are the main component of the indirectflight muscles fbr the down stroke of the wings. In the female ofA, nigrapkrga, which lackswings, the ¢ ontraction of these muscles produces shortening of the longitudinal length of thethorax and drawing of the head towards the therax. As mentioned above, this change of

sclerites of the anterior pertion of the female body staying in the pupal exuviae is effective to

plug the soft content (female body) in the exuviae, and to protect the female against enemies.

In Dierl (1964), the dorsal longitudinal muscles ofthe pro- and rnesothoracic nota are greatlyreduced in the females of the genera ,Rsyche (as Fbemea) and Bruandia, Rsyche casta still





retain one dorsal longitudinal muscle in the prothorax, but it is very thin. R crassioretla and

.a comiteZ?tx entjrely lose the dorsal longitudinal muscles in these thoracic segments. Bycontrast, the metathoracic nota ofthese species have several longitudinal dorsal muscles in themetathorax. The reduction or absence of the dorsal muscles in two anterior thoracicsegments in these species belonging to the 7-grade is certainly related to the fact that the headis rigidly set to the prothorax in female adu]ts.

In the female A. nigTaplaga, the muscular system ofthe abdomen is well developed, particu-larly in the 3rd to 6th abdominal segrnents, The constriction and the swelling of a part of

the body during the vermiculation movement are most prominent in these segments. Thelongitudinally arranged dorsal and ventral muscles of these segments are effective for theswelling of the segment to which they belong. The wide transverse layer of the lateralmuscles together with some obliquely arranged dorsal and ventral musc1es are etfective fbr theconstriction of the segment to which they belong. Thus these abdominal muscles are very

important to only one locornotive movement ofthe vermiform females. Jn Dierl (1964), themusculature in the middle abdominal segments in Rsyche and Bruandia is more simple thanin A. nigraplaga, and the lateral muscles seem to consist of very sparsely set muscle fibers,As the females of these genera do not perform distinctive vermiculation movement, they need

not develop the lateral muscles in the abdominal segments.

Although the female `Lovipositor"

is greatly shortened in the female ef A. nignap2tzga, most

muscles, which contrl the movement of the ovipositor, are well retained as in the generaRsyche and Brttandia (Dierl, 1964). When the female lays eggs, she may direct the apex of"ovipositor"

to a wide range of directions using the elevator, the fiexor and the adductor

muscles, which are inserted on the basal ponion ofthe papillae anales, The protractor andretractor muscles attaching to the apex of the apophysis posterioris are also important fbrIaying eggs,

3. Concluding remarks (Evolutional significance of the reduction and specialization of

morphology and behaviours in the female)

1) The body substance ofthe female accumulated during the larval period is most effective]y

used in the adult stage to develop the mature eggs by the extreme reduction of the external

structure including the thinning of the integumental cuticula and the reduction of bodymusculature, especially that in the thorax,

2) Double protective devices, the larval case and the pupal exuviae, fbr the female adultagajnst natural enemies and environmental factors enable the female to greatly reduce theexternal structure and to membranize and soften most of her body integument.

3) The body musculature ofthe female is almost confined to the fotlowing three functions:the protection of the anterior portion of the female body in the exuviae by the compression

of the sclerotized head towards the soft ventral area of the thorax; the progressive and

retrogressive movements in the pupal exuviae and the larval case by the verrniculation caused

by the dorsal and ventral longitudinal muscles and transverse lateral muscles; the orientation

of the shert and soft "ovipositor"

to a wide range of directions controlled by a fewcorresponding muscles to fi11 the pupal exuviae with eggs.

4) Throughout the process of simplifying or reducjng the external structure of the female,morphogenesis towards the adulz stage is delayed, Consequently character states similar to

those in the larval stage are retained or are fbrmed fbr the head and thoracic appendages.

This delay of formation of adult structure together with reduction of wings may be considered



The 　Lepidopterologioal 　Sooiety 　of 　Japan

330 Mika 　SuG且MoTo 　and 　Toyohei　SAIGusA

as　a　result 　of 　neotenic 　evolution 　in　the　psychid　phylogeny．

Acknowledgements

One 　of 　the　authors，　Sugimoto

，　expresses 　her　sincere 　thanks　to　Prof．　O ．　Yata ，　Prof 　H ．　Shima

and 　Assoc．　Prof．　K ．　Araya　of　Kyushu　University　f（）r　their　constant 　guidance　and 　encou エage −

ment 。

References

Dier1，　W ，

，1964．　 C ｝確010gie

，　Morphologie 　und 　Anatomie　der　Sackspinner　Fumea 　 casta （Pa1且as） und

　　cra ∬ iorella（Bruand）sowie 　Bniandia 　comitella （Bruand ）（Lepidoptera ，　Psychidae）皿 it　Kreuzungsver −

　　 suchen 　zur 　Klarung 　der　Artspezi盒tat．　 Zoo∠ 乃．（Systematik）91： 201−270，

　　　　，1966．　Psychidae（Lep．）aus 　NepaL　 Ergebn．　 F∂rsch 　Un　tern　eh 　mens 　Nepal 石励 α 〜的〜a 　1： 322−

　　 342．

　　　　，1973． Hypodermale　 Drusenfelder　 in　 Thorax　 und 　 Abdomen 　 apterer 　 Psychidae−Weibchen ，

　　Opusc ，　ZooL 　127 ：レ 8．

Entwistle，　P．　F，，1963．　 Observations　on 　the 皿 orphQlogy 　of　sQme 　adult 　females　and 　immature　stages　of

　　fbur　sp ies　of 　Psychidae （Lepidopera ）on 　Theobroma　cacao 　L．　in　Western　Nigeria．　 Proc．　R．　 en ・t．

　　 Soc．　Lon 　d．（B）32： 72−80．Saigusa

，　T ，，1962．　 On 　some 　basic　concepts 　of 　the 　evolution 　Qf　psych｛d−nloths 　from　the　points　ofview 　of

　　the　comparative 　ethology 　a【1d　mQrphology ．　7ン∂ Ga　12； 120−143（in 亅apanese ）．

　　　　，1972．　Life　history　of 　Psychidae．　 Shokubtttsu　B ∂ek ゴ 26； 147−152 （in　Japanese）．

　　　　，1981．　Life　history　of 　Eu 〜veet α レα而eg 硴 α ．　Anima （99）二 29−36 （in　Japanese），

Seino，　A ，，1977．　 Miscellaneous　notes 　oll　the 　Psychidae，　VII．　 Yugat∂（69）： 79−86 （in　Japanese）．

Sugawara，　H ，，　Honma ，　K ．，　Ujiye，　T．＆ H ．　Furihata，1963．　 Studies　on 　the 　Nitobe 　Bug 　Worm 　Moth ，

　　 Mahasena 　nitobei 　Matsumura，　ln免 sting 　apples ．　 BulL 乃碗 icuZ　Res．　Stn （C），　Morioka （1）： 123−147

　　（in　Japanese）．Sugimoto

，　M ．＆ T ．　Saigusa

，2001．　 A 　 new 　genus　of 　the 　subfamily 　Oiketicinae　from　Asia （Lepidotera，

　　Psychidae）．　 Tinea　16 （in　press）．Yano ，　K ．，1958．　 Studies　on 　the 　bagworm 　moth 　ofthe 　Kinki　district（Lepidoptera，　Psychidae）．　 PublSθ鷹

　　 LabL　Univ．　Osaka　Prefect．（4）： 25−39　（in　Japanese）．

摘要

特殊化したミノガ科の 1種，ネグロミノガ Acanthopsyche　 nigraplaga （Wileman）の雌の外部形

態と筋肉系に関する研究（鱗翅目）（杉本美華・三枝豊平）

ミノガ科の中で ♀の形態の退化が著しく進んでいる δ 段階（三枝，1962の分類）に属するネグロミノ

ガの ♀の外部形態と胸部及び腹部の筋肉系について調査した．

外部形態については，頭部と胸部が著しく小型化すると共に，その付属肢や翅などは著しく退化する

かまたは消失しており，逆に腹部は著しく容積を広げ，末端の産卵器は短縮していた．頭部には触角の

痕跡，口器の痕跡が現れていた．触角の痕跡は単に円錐状のものから，分節が見られ，幼虫の触角にや

や類似した様相を示すものまで変化が見られた．口器については，最も発達した個体では，大腮が不規

則な形状の微小で扁平な骨片として現れ，小腮が下唇の両側に小隆起として現れ，下唇は大型円錐形

の突出部で基部を取り巻く骨化部や先端の下唇鬚ないし吐糸管の痕跡と思われるものが認められた．

複眼や個眼．構造は失われていたが，触角基部の外側の頭蓋のクチクラは退色して，この直下に眼点の

黒色の組織が存在した．膜状骨前孔は顕著で，頭部中央のやや側方に開口していた．幕状骨は細いが，

よく発達していた．胸部は背域が弱く骨化し，側域と腹域はほとんど膜状であった．中胸背域側部には

個体によって弱い膨出部が認められたが，

これは前翅の原基の痕跡の可能性がある．胸脚は痕跡的で

あるが，しぼしぼ 2−3節に不完全に分節し，その形状は幼虫のそれに類似していた．胸部の腹中線域に

N 工工一Eleotronio 　Library 　



The 　Lepidopterologioal 　Sooiety 　of 　Japan

External　Morphology 　and 　Musculature 　of 　Female 　Aeanthops アc舵刀 igraplaga 331

は微小な骨片が現れることが多く，これは furcasternumの痕跡であろう．腹部は第 1腹節の背域と第 8

腹節及び肛門葉の基部を除いて全て膜質化する．第 8 腹節は環状の骨化が認められ．本来の前陥入突

起はほとんど消失していた．肛門葉は小形で，大部分が膜質化し，微小な毛を生じていた．後陥入突起

は短いが，存在し，その末端は第 8腹節に達していた．

筋肉系は胸部では著しく退化し，腹部ではよく発達するが，筋肉は著しく薄く膜状であった．前胸及び

後胸にはやや発達した背縦走筋が認められたが，その他の筋肉はほとんど認められなかった，後胸に

は著しく細い背縦走筋が認められた．第 1腹節の筋肉系は第 3−6腹節のそれにやや類似しているが，かなり退化していた．第 2 腹節の筋肉系は第 1 と第 3−6 腹節のものの中間的な状態であった．第 3−6

腹節の筋肉系はほぼ同じで，Fig．　lo に示したように，よく発達していた．特に背縦走筋と腹縦走筋は帯

状に発達し，また背域と腹域を結ぶ側筋は表皮に接して膜状に幅広く発達していた．第 7腹節の筋肉

系はそれより前のものにやや類似しているが，縦走筋は背腹ともに外縦走筋の発達が悪く，内縦走筋が第 8 節の骨化部に付着していた．第 8腹節からは肛門葉を上下に動かす挙筋と屈筋，内転筋，及び後

陥入突起の伸縮に関与する筋肉が認められた．

これらの外部形態及び筋肉系と，雌の行動との関連は以下のとおりである．

D　頭部と胸部の骨化は，羽化（蛹から成虫への脱皮）において，蛹の頭部及び胸部クチクラを裂開す

るために一

定の機能を持っていると考えられる．ただ，この部分には特殊な突起を有しないので，蛹の

頭部及び胸部のクチクラをオオミノガの場合のように破壊することはできない．

2）前胸及び中胸の背縦走筋は，その収縮によって頭部及び胸部背面の骨化部を体の前下方に屈曲さ

せることが可能で，それによって蛹殻内での唯一

の外界と接する面を閉ざし，軟弱な腹部などを，外敵から保護する機能を持っていると考えられる．

3）体の大部分が膜質化しているのは，雌が蛹殻及びミノの中を移動する唯一の運動手段である蠕動

運動を円滑に行うために寄与していると考えられる．同様に腹部の縦走筋及び側筋は，蠕動運動が顕

著に認められる第 3−6腹節でよく発達しており，これらの筋肉も蠕動運動に寄与するところが大きい

と考えられる．

4）肛門葉を含む産卵器は短縮し，先端はほとんど膜状で軟弱であるが，その方向を自由に転回でき

るための筋肉系は発達している．これによって，蛹殻内にいる雌が，その底部から卵を詰めていく産卵

様式を可能にしている．

なお，これらの構造の進化学的意義は以下の通りである．

1）成虫期の外部構造を極端に退化させ，それに関連する筋肉を退化させ，また表皮のクチクラを薄

層化する事によって，幼虫期に獲得した体物質の大部分が卵巣の成熟に向けられることが可能になっ

ていると考えられる．

2）　ミノ及び蛹殻という二重の保護構造が，表皮が軟弱で，付属肢などを欠いている無防備な雌を進

化させ，またそれを保護する手段になっている．

3）腹部の筋肉系は以下の 3機能に集約されている；前胸と中胸の背縦走筋で頭部を胸部腹側に屈曲

させて，雌の体を保護する機能；第 3−6腹節に最もよく発達した背・腹縦走筋と側筋によって蠕動運動

を行う機能；産卵器に付随した筋肉によってその方向をかなり自由に転回できる機能．

4）雌成虫の体を単純化ないし退化させる過程で，成虫に向かう形態形成が遅滞し，その結果，幼虫の

それに類似した構造が頭部や胸部の外部形態に現れている．これは成虫の翅の退化を考慮すると，ミ

ノガ科の進化におけるネオテニー的傾向の現れであると解釈できる．

（Accepted 　April　17，2001）

Published　by　the　Lepidopterological　Society　of　Japan，5−20，Motoyokoyama 　2，　Hachioji，　TQkyo，192−0063　Japan

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