The female abdomen of the viviparous earwig Hemimerus vosseleri

57 Pages·2001·1.77 MB·English

ZoologicalJournaloftheLinneanSociety(2001),131:251–307.With38figures
doi:10.1006/zils.2001.0246,availableonlineathttp://www.idealibrary.comon
The female abdomen of the viviparous earwig
Hemimerus vosseleri (Insecta: Dermaptera:
Hemimeridae), with a discussion of the postgenital
abdomen of Insecta
KLAUS-DIETER KLASS
Zoological Museum, University of Copenhagen, Universitetsparken 15, DK-2100 Copenhagen Ø,
Denmark
ReceivedJune1999;acceptedforpublicationJanuary2000
The viviparous, epizoic African earwigs of the genus Hemimerus are currently regarded as the sister taxon of the
remaining Dermaptera (Forficulina). Exoskeleton, musculature, and part of the nervous system of the female
abdomen, from segment IV on, are described. The morphological interpretation and homology relations of most
componentsarediscussed,usingpreviousandoriginaldataonForficulina,Zygentoma,Ephemeroptera,Orthoptera
and Dictyoptera as a comparative framework. In the mid-abdominal segments some interesting similarities with
Zygentomaareindicated.Focalissuesinthepostgenitalabdomenaretheterminaldorsalsclerites,thecercalmuscles,
andtheparaproctsandassociatedmuscles.Earlierhypothesesonthedermapteranpostabdomen(opisthomereand
pseudocercushypotheses)andresultsfromontogeneticstudiesarescrutinized.Someinterestingfeaturesdetected
infemaleHemimerusaretheimmobilizationoftergaVIII–Xbymeansofathickinternalcuticlelayer,thelackof
dorsal muscles on these terga, the shift of some insertions of cercal and rectal muscles from tergum X to tergum
IX, and minute pits on the venters IX and X that could be spiracle vestiges. Some of these features occur also in
otherDermaptera.SomeabdominalcharacterssuggestthatHemimerusisnestedwithintheForficulina.Thelack
oftheclasper-shapeinthecerciisnotastrongargumentagainstthis. 2001TheLinneanSocietyofLondon
ADDITIONAL KEY WORDS: cercus – genitalia – paraproct – postabdomen – Archaeognatha – Dictyoptera –
Ephemeroptera–Zygentoma.
INTRODUCTION 1984,1985).Theknowledgeofabdominalmorphology,
however,hasremainedveryincomplete:extantdescrip-
The genus Hemimerus has long been of particular tions of the exoskeleton are superficial, and data on
interest to entomologists, on the one hand for its vi- themusclesandperipheralnervesareentirelyabsent.
viparity and its habits as an epizoic on Cricetomys Information on these issues would be important for a
rats,ontheotherforthedebateonitstaxonomicrank convincing phylogenetic placement of Hemimerus.
eitherwithinorbesidetheDermaptera(Popham,1961; ThefirsttoclaimacloserelationshipofHemimerus
Giles,1974).Hansen(1894),Verhoeff(1902),andJor- to the typical earwigs, Dermaptera Forficulina, was
dan(1909)werethefirsttogiveusefultreatmentson Hansen (1894). Verhoeff (1902) and Jordan (1909),
the external and internal morphology of Hemimerus. findingfurthersimilarities,agreedwithhim.Popham
Deoras (1941a,b) gave some additions. Davies (1966) (1961) proposed to exclude Hemimerus from Derm-
described changes in external morphology during aptera,butGiles(1974)suggestedreinstatingitwithin
nymphal development. Heymons (1912) studied the Dermaptera. Nevertheless, both workers actually
internal genitalia and early ontogeny in detail. Head agreed that Hemimerus is the sister taxon of the (re-
and thorax morphology were exhaustively treated in maining) Dermaptera (i.e. Forficulina including Arix-
somemorerecentcontributions(Popham,1962;Barlet, enia), their debate focusing on the ‘importance’ of
certain characters and the taxonomic rank (order or
suborder) of the groups in question. Popham (1985)
E-mail:[email protected] re-examined the basal phylogeny of the Dermaptera
251
0024–4082/01/030251+57$35.00/0 2001TheLinneanSocietyofLondon
252 K.-D.KLASS
at some length and affirmed that Hemimerus is the cranidae), Pygidicrana v-nigrum Serville, 1831 (For-
sister taxon of the remaining Dermaptera. Many of ficulina: Pygidicranidae), Diplatys sp. indet. (For-
his arguments, however, are not very convincing. Al- ficulina: Pygidicranidae),Pyragra fuscata brasiliensis
ternatively, one might suspect that many of the fea- (Gray,1832)(Forficulina:Pygidicranidae),Karschiella
turesinwhichHemimerusseemsmoreprimitivethan buettneri(Karsch,1886)(Forficulina:Pygidicranidae),
the Forficulina could be due to secondary reduction, and Ctenolepisma lineata (Fabricius, 1775) (Zyg-
especially to paedomorphosis. Barlet (1985: 186) sus- entoma:Lepismatidae).‘Forficulina’isusedheresensu
pectedsuchpaedomorphicapomorphiesinthoraxmor- Popham (1985), i.e. as including the Arixeniidae. It
phology.Hence,itcannotbeexcludedthatHemimerus should be noted that the Pygidicranidae as delimited
is nested within the Forficulina. More detailed mor- herein(includingDiplatyidaeandKarschiellidae)area
phological information is, however, obviously needed paraphyletic assemblage comprising the lowest-grade
before reasonable conclusions can be drawn. Forficulina (see Haas, 1995); the phylogenetic re-
In the present study, the abdomen of female Hemi- lationships between their genera are largely un-
merusisdescribedfromsegmentIVon,thusincluding resolved.Whendatafrompreviousstudiesarereferred
typical (mid-abdominal: IV–VI), genital s.l. (VII–IX), to, the names of the respective taxa, mostly species,
andpostgenitalsegments(X,XI),andthetelson.Exo- arespecifiedas(in)completelyasintheoriginalpapers.
skeletonandmusculatureareconsideredexhaustively; Aftertheirfirstmentionspeciesaredesignatedbythe
only setae, tracheae, and details of the hindgut are generic name alone.
omitted. The nervous system is treated as far as pos-
siblewiththematerialathand.Thehomologyandthe
TERMINOLOGIES, MORPHOLOGICAL
morphologicalinterpretationofthecomponentsunder
INTERPRETATIONS AND ABBREVIATIONS
considerationarediscussedinawidesystematicframe,
using selected other lower-grade Insecta for com- EXOSKELETON
parison. Archaeognatha and Zygentoma are included
The terminology follows essentially Snodgrass (1931,
because many components are present in a more ple-
1933, 1935b). However, the ventral (s.l.: sternal and
siomorphic condition than in Dermaptera and other
pleural)abdominalsclerotizationsareinterpretedand
Pterygota,andbecausethesemoreprimitiveconditions
designated based on more refined results on Ar-
are important for the interpretation of many struc-
chaeognatha (Bitsch, 1973, 1974a,b), Zygentoma
tures. Ephemeroptera, Dictyoptera, and Orthoptera
(Rousset,1973),andDictyoptera(Klass,1998).InAr-
are included because for these the literature contains
chaeognatha an abdominal segment has maximally
the most elaborate data base on abdominal mor-
five discrete ventral sclerites: the unpaired sternite
phology. The highly controversial homologies and in-
and intersternite and the paired coxites (bearing the
terpretations of the postgenital abdominal sclerites stylus),laterocoxites(=subcoxaeinSmith,1969),and
andmusclesareafocalissue.Furthermore,thephylo-
precoxites (e.g. Bitsch, 1973: fig. 2, 1974a: fig. 1). A
geneticinformationcontentofanumberofabdominal
synthesis from Bitsch’s findings in Archaeognatha,
charactersisexamined,andtheirbearingonthephylo-
Rousset’s results on Zygentoma, McKittrick’s (1964)
genetic placement of Hemimerus and on other inner-
descriptions of nymphal Blattaria, and conditions in
insect relationships is analysed.
adult Dictyoptera led to an identification in these
taxa of homologous sclerotization areas and muscle
insertions on the venters of the female genital seg-
MATERIAL AND METHODS
ments VIII and IX (Klass, 1998). Sclerites cor-
Of Hemimerus vosseleri Rehn & Rehn, 1935 (Hemi- responding to coxite and laterocoxite of
merina: Hemimeridae) five females preserved in 80% Archaeognatha, and, accordingly, also the division
ethanol were available. Most structures were studied between them, could be determined in Dictyoptera
by dissection under a stereo microscope: dorsally, lat- (gonocoxa and laterogonocoxa in Klass, 1998; later-
erally, and anteriorly in 80% ethanol. For small ogonocoxa IX=gonangulum). Sclerites corresponding
muscles and some other structures the identity of tosternite,intersternite,andprecoxite,however,could
the tissue was checked under a light microscope. For not be identified because in Archaeognatha none of
occasional comparison with Hemimerus and for the thesesclerotizationsbearsmuscleinsertionsthatcan
reinvestigation of certain characters, specimens were be homologized with muscle insertions of Pterygota
used of Apachyus chartaceus (de Haan, 1842) (For- (compareBitsch,1973:e.g.fig.8);noristhereahypo-
ficulina:Apachyidae),Labidurariparia(Pallas,1773) thesis for the demarcation of these sclerotizations in
(Forficulina: Labiduridae), Forficula auricularia Lin- Zygentoma. Nevertheless, small unmuscled median
naeus, 1758 (Forficulina: Forficulidae), Echinosoma sclerites in Dictyoptera were tentatively determined
yorkense Dohrn, 1869 (Forficulina: Pygidicranidae), as homologues of sternite and/or intersternite and
Tagalina burri Hincks, 1955 (Forficulina: Pygidi- were referred to as the sternum. It is furthermore
ABDOMENOFH.VOSSELERI 253
conceivablethatthehomologueofthearchaeognathan delicate, hollow or massive, sclerotized to various ex-
precoxite is included in the anterior portion of what tentsorentirelymembranous,shapeshowsmuchvari-
has been called in Dictyoptera and Zygentoma the ation, and these attributes occur in many
laterogonocoxa. combinations. There is no consistent terminology for
Hence, the distinction of three major sclerotization the various types. Moreover, as shown by cor-
areas is, as far as presently known, possible in the responding muscles being attached to them, such in-
venters VIII and IX of female Dicondylia. These are ternal projections of very different kinds can
called here coxa (=gonocoxa), laterocoxa (=latero- apparently be homologous or homodynamous (=seri-
gonocoxa), and sternum, and these terms are here allyhomologous),andaterminologicaldistinctionap-
more consistently applied than in Klass (1998). Coxa pearsthusnotquiteappropriate.Theterms‘apodeme’
and laterocoxa are paired limb base sclerotizations and ‘tendon’ are used herein to designate sclerotized
designated here collectively as the coxopodium and membranous internal cuticular projections, re-
(pleural). Coxopodia and the unpaired sternum to- spectively,and‘ridge’referstoanapodemehavingthis
getherconstitutethecoxosternum.Alsotheabdominal shape.Thesetermsaremoreorlesssynonymousrather
‘sterna’ I–VII of Dicondylia are regarded as such thanmeantasstrictcategories.‘Tendon’isnotreferred
coxosterna(seeHeymons,1895a:27;Snodgrass,1931; heretonon-cuticularendoskeletalcomponents.Ofthe
Smith, 1969). On the base of the abovementioned latter some ventral ones of Archaeognatha and Zyg-
findingsitisattemptedheretotracetheventralsclerite entoma are considered herein, which are called ‘en-
components and hence the sclerite homologies with dosternites’.
Archaeognatha, Zygentoma, and Dictyoptera also in Sclerites,andalsoendosternites,areheredesignated
thefemalegenitalsegmentsVIIIandIXofHemimerus by terms composed of two upper case letters. In the
and, in part, other Dermaptera. It is moreover at- segments up to IX sclerite designations are based
tempted to demarcate the homologous sclerotization on the above explanations. Formative elements are
areas in the mid-abdominal coxosterna and in the designatedbytermscomposedoftwolowercaseletters.
sclerotizations of the terminal segments X and XI. A number in the last position gives, if needed, the
It should be noted that, first, this demarcation of assignment of a sclerite, endosternite, or formative
areashomologouswiththegenitalcoxae,laterocoxae, element to a segment. Exoskeletal structures not
and sterna does not imply that the mid-abdominal coveredbythesetermsaredesignatedbysinglelower
coxosterna and Xth/XIth-segmental sclerotizations case letters. It should be noted that generally in this
wereeveractuallydividedintocorrespondingdiscrete paper the equal designation of components expresses
sclerites, i.e. that such a division is ancestral for the theassumptionofhomologyindifferenttaxaorserial
abdominal segmentsof Insecta—thoughconditions in homology in different segments, with the restrictions
someArchaeognathaandPterygotamayindicatethis. given in the discussions in terms of the probability of
Second,theuseof‘coxa’isnotmeanttoindicatestrict (serial) homology.
serial homology with the thoracic coxa, in particular
because the serial homologue of the abdominal coxa-
MUSCULATURE
stylus border in the thoracic leg is unknown. Third,
The muscles are numbered in sequence. In addition,
the interpretation of the archaeognathan sclerites in
many muscles are given descriptive names. The ter-
a wider arthropod context is largely unresolved (see
minological principles followed, their inherent prob-
Bitsch,1973:193f,1994;Smith,1969),andnoreference
lems,andthetermsusedforcharacterizingthemuscle
is intended here, with the distinction between coxa
shapeareexplainedinKlass(1999:5f).Inthesegments
andlaterocoxa,totheoriesoflimbbasecompositionin
IV–VIIinsertionsonacoxosternumandonthepleural
alarge-scalearthropodview.Itisemphasizedthatthe
membrane—most of both are probably pleural—are
terminology as used herein is meant to indicate only
designatedhereascoxosternal.Adistinctionbetween
inner-insect abdominal homologies and serial homo-
tergal(s.s.)andparatergalinsertionsisattempted(but
logies, and only in this frame (serial) homologies are
istentative)inordertocomparetheresultswiththose
here traced. The problems in interpreting the ar-
on Dictyoptera (Klass, 1999, 2000). Most muscles are
chaeognathan sclerites have probably no impact on
presentasapair,andanunpairedconditionisnoted.
this comparison within the insect abdomen; only the
terminologymayhavetobemodifiedwhentheseprob-
lems are solved. NERVOUSSYSTEM
Formative elements, established by an in- or out- All major components are designated by single upper
foldingorbyathickeningofthecuticle,areconsidered case letters: ganglia, connectives, major nerves, and
herein as discrete structural components of the ab- perisympathetic organs. A number in front gives, if
domen.Manyoftheseareinternalcuticularprojections needed,theassignmenttoasegment.Compoundgan-
used for muscle attachment; they can be stout or glia, composed of several segmental ganglia, are
254 K.-D.KLASS
termed, for example 7–11G. Primary branches of the ct tendons on cercal base
major nerves are specified by numbers behind the CX (+number) coxa (number=segment)
letter; the numbers correspond to those of the ho- df dorsal fold of segment overlapping
mologous nerve branches of Dictyoptera (see Klass, succeeding segment
1999). The part of a nerve that continues beyond the dr longitudinal dorsomedian cuticular
originsofitsbranchesiscalleditsmainpart(definition ridge on tergum
arbitrary).Detailsoftheterminologicalprinciplesfol- DT dorsal sclerite of telson
lowed, and their inherent problems, are explained in ec line along which cuticle ends (meso-
Klass (1999: 6f). derm adjoining)
ei inferior hind edge of subgenital fold
es superiorhindedgeofsubgenitalfold
SEGMENTALASSIGNMENT
ES (+number) endosternite (number=segment fol-
For sclerites this is given with respect to secondary
lowing)
segmentation because the latter is established by the
G ganglion
sclerites. For formative elements, muscles, and com- gl (+number) projecting body of abdominal limb;
ponentsofthenervoussystemassignmentisgiven,as gonoplac on segment IX (number=
faraspossible,withrespecttoprimarysegmentation.
segment)
Componentsassumedtoliebetweentwoprimaryseg-
go anterior border of definitive genital
ments or to be of bisegmental origin (e.g. antecostae,
opening
alarymuscles,anteriortergo-coxosternalmuscles,en- gp (+number) gonapophysis or corresponding area
dosternites) and the connectives, median nerves, and (number=segment)
transverse nerves are formally assigned to the re-
il posterior incision of subgenital fold
spective posterior segment (compare Klass, 1999: 7).
L connective between ganglia
In the segments up to VII, and partly in VIII and IX,
LC (+number) laterocoxa (number=segment)
the fact that most components belong to a certain
LP lateral plate (lateral part of para-
primary segment is obvious from their positions. For
proct)
many elements behind segment IX, however, the as-
lt lateral tendon beside coxosternum
signmenttoacertainsegmentiscontroversial;reasons
M median nerve
aregiven,butfirmconclusionscannotbedrawnwith-
ma median apodeme on cercal base
out further detailed ontogenetic studies.
ms (+number) manubrium of spiracle (number=
segment)
ABBREVIATIONS mt (+number) median tendon or ridge of coxo-
1 .... 51 muscles sternum (part of antecosta; number
I .... IV groups of cercal muscles =segment following)
A (+number) dorsalnerve(anditsmajorbranches) oc common oviduct
a desclerotized patch anterolaterally ol lateral oviduct
on tergum P perisympathetic organ
ac (+number) antecosta (number=segment fol- pc transverse cuticular ridge on coxo-
lowing) sternumortergumbehindantecosta
ag accessory gland re rectum
an anus rp rectal papilla
AP analplate(medianpartofparaproct) sb subanal lobe
at (+number) tendon or apodeme anterolaterally si (+number) spiracle (number=segment)
oncoxosternum=‘sternal’apophysis sl (+number) stylus area (number=segment)
(number=segment following) so spermathecal opening
B (+number) anteriorventralnerve(anditsmajor sp spermatheca
branches) ST (+number) sternum (number=segment)
b fusion between terga IX and X T transverse nerve
c membranous stripe incompletely tf terminal=caudal filament on ter-
separating sclerites LC8 and CX8 gum XI
C (+number) posteriorventralnerve(anditsmajor TG (+number) tergum (number=segment)
branches) tl lateraltubes(openingnearaccessory
CE sclerotization of cercus gland)
ce cercus tr transverseridgeondorsalscleriteof
CP (+number) coxopodium (number=segment) telson
CS (+number) coxosternum (number=segment) va vagina
ABDOMENOFH.VOSSELERI 255
vf (+number) ventral fold of segment overlapping
succeeding segment (number=seg-
ment); subgenital fold on venter VII
vr longitudinal ventromedian cuticular
ridge on coxosternum
Inaddition,abbreviations,terms,andmusclenum-
bers from other contributors are used in the com-
parisons between Hemimerus and other Insecta. In
thetexttheseareconsistentlymarkedwithanasterisk,
but not in the tables and illustrations. When used in
theillustrations,theseabbreviationsareexplainedin
the respective legends (Figs 25–38).
DESCRIPTION OF THE ABDOMEN OF
HEMIMERUS VOSSELERI
EXOSKELETONOFHEMIMERUS
Conditionofthecuticle
Thecuticlewasobservedtohaveinmanyareasofthe
bodywalltwolayersthatareeasilypeeledapart.The
external layer shows clearly the pattern of sclerot-
ization (stiff, brown) and membrane (flexible, trans-
parent). The internal layer, though brownish in some
areas, is milky and has a rubber-like texture and
flexibility.Itisunclearinwhichwaythis‘mechanical’
subdivision meets any biochemically or ultra-
structurallydefinedlayeringofthecuticle(thedelicate
epicuticlebeingoutofdiscussion).Inthedescriptions
the relative contribution of the two layers to specific
structures is only occasionally considered.
Cuticlethicknessvariesconsiderablyalongthebody Figure1. Exoskeletonofmid-abdominalsegments.Left
surface. A thickening of the cuticle can be due to a halfofsegment,internalview.Dorsalpartbent,lyingin
same plane as ventral part. ↑ dorsomedian, ↓ ven-
thickeningofeitherorbothofitstwolayers.Thickened
tromedian,→anterior.Ridgesdrandvrlocatedatdorsal
areas, if sclerotized, usually appear darker. In some
andventralmidline.Sclerotizationdark.Cuticularridges/
areas,thick cuticleiswell delimitedfrom thethinner
thickenings indicated by hatched stripes/areas. Dashed
surrounding cuticle. Information on the extension of
line:lateraledgeoftergum.Scalebar=0.5mm.
these distinct thickenings, which form ridges or
patches,isincludedwherepossible.Othercaseswhere
cuticularthickeningislessstrong,orwheretheareas
tergumorcoxosternum.Thecoxosternumformsatits
ofthickeningarenotwelldelimited,arenotconsidered.
anterolateral corner a strong apodeme at (‘sternal
apophysis’), whose external face is mostly mem-
ExoskeletonofsegmentsIV–VI branous.
These mid-abdominal segments (Fig. 1) have, when A wide pleural membrane extends between the lat-
observedinanundistortedcondition,thetergumTGin eral margins of coxosternum and tergum. It bears,
aslightlymoreanteriorpositionthanthecoxosternum near the margin of the coxosternum, a small tendon
CS. The lateral parts of a tergum gradually incline lt and, more anteriorly, the spiracle si. The spiracle
ventrad and mesad and overlap the lateral parts of hasadish-shapedatrium,whichisborderedinternally
thecoxosternum,especiallyintheanteriorpartofthe by a neck-like constriction to the base of the trachea.
segmentwherethetergumisbroader.Bothtergaand Somedetailswereobserved(comparedescriptionsfor
coxosterna broadly overlap their succeeding counter- DictyopterainKlass,2000).Theneckbearsatongue-
parts (folds df, vf in Figs 1, 2). Most of the cuticle shaped, anteromesad-directed apodeme, the manu-
bending forward from the sclerites’ posterior edges is brium ms. The tracheal base immediately internal to
weakly sclerotized (Fig. 1, left margin), the sclero- the neck has a narrow ring-shaped zone with ana-
tization being regarded here as part of the respective stomosing ridges that enclose circular or indistinctly
256 K.-D.KLASS
Figure2. Musculatureandnervoussystemofmid-abdominalsegments.Lefthalvesofsegments,internalview.Four
successivestagesofdissectionareshown,aswouldapplytosegmentsIVtoVI.Fromrighttoleft,musclesandnerves
aresuccessivelyremoved(leftnervescutbybars).Dorsalpartbent,lyinginsameplaneasventralpart.↑dorsomedian,
↓ventromedian,→anterior.Sclerotizationdark.Musclesstripedaccordingtocourseoffibres.Nervesblackfromtheir
rootsonward.Nervebranchessupplyingamuscleendingwithablackdot.Cuticularridges/thickeningsnotindicated
(see Fig. 1). Dashed lines: lateral edge of tergum, hidden borderlines of muscles and their insertions. Scale bar=
0.5mm.Spiracleareashownseparatelyonupperleftmargin,2.5×enlarged.
ABDOMENOFH.VOSSELERI 257
polygonal craters (in Dictyoptera designated as zone carina in Rehn & Rehn, 1935). The ventral anterior
ZE∗).Internaltothiszone,andsharplydelimitedfrom marginoftheterminalscleriteTG11+DT(Fig.5)fits
it, the taenidial sculpture of the trachea begins (in intotheshallowgrooveinbetween(Fig.4;submarginal
Dictyoptera designated as zone ZF∗). The atrium has sulciform impression in Rehn & Rehn, 1935). In this
a sculpture resembling that in zone ZE∗. For the waythevestibulum(thechamberabovethesubgenital
closingmechanismseeDeoras(1941b;mup∗therein= fold) can be closed. The left and the right side differ
manubrium). slightly in the outline of the edges ei and es.
Both tergum and coxosternum have a strong ante-
costa ac along their entire anterior margins and, in
the middle part, an accessory transverse ridge pc ExoskeletonofsegmentsVIIIandIX
immediately behind the antecosta. From ridge pc ThetergaTG8andTG9areveryshort(Figs5,6)and
arises, in the midline, a posteriad-directed ridge vr entirely covered by tergum VII (i.e. by df7). Both
(ventral) or dr (dorsal). The coxosternal antecosta narrowly overlap their succeeding counterparts (by
broadens laterally to occupy the entire apodeme at, df8, df9 in Figs 5, 6, 10). Distinct antecostae are
rendering it very stout. The tergal antecosta has a wanting. In the literature it is claimed that the terga
smalllateralarea(ainFig.1)thatlackssclerotization VIII,IX,andXarefused(e.g.Giles,1963:134).How-
but is as thick as the remaining antecosta; it works ever, the relations are more complicated. Regarding
asanintrinsicarticulationofthetergum.Thepartof onlytheexternalcuticularlayer(Figs5,6),thethree
the tergum lateral to point a is called here the pa- terga are all free from each other: the tergal sclerot-
ratergite(thoughthereisnocompleteseparation:see izationsarewell-bordered;fromtheirhindedgesmem-
definition in Snodgrass, 1935b: 81; homology with branebendsanteriadtowardstheanterioredgeofthe
sclerotizationscalledparatergitesinotherInsectaun- followingtergum.Theunmelanizedinternalcuticular
resolved). layer (shown together with the external layer in Fig.
10), however, fills the folds df between sclerites and
membranes.Theinternalsurfaceofthecuticleisthus
ExoskeletonofsegmentVII aneven planeallover thetergaVIII–X.Hence, there
TergumTG7,thepleuralmembranewithspiraclesi7 isnotafusion(lossofmembranebetweensclerites)of
and tendon lt7, and the anterior part of coxosternum terga VIII–X, but the thick internal cuticular layer
CS7arelargelyasinamid-abdominalsegment,though holds all sclerites and membranes in a firm position
the ventral ridges pc and vr are wanting (or poorly (Icallthistergalimmobilization).Onlythelateralmost
indicated), and the broad lateral parts of the coxo- parts of terga IX and X are actually fused, without
sternalantecostaextendfarthertotheposterior(Fig. membrane or overlapping between them (b in Figs 5,
3).Theposteriorpartoftheventer,however,formsas 6).
inotherDermapteraasubgenitalfoldvf7(Fig.3).This On the ventral side each segment bears a pair of
fold differs from its counterparts vf in the preceding conspicuouslateralsclerites,whichareseparatedme-
segments (Fig. 1) by a much more extensive over- diallybythelargegenitalopening(Figs5,6;sclerites
lapping of the area posterior to it, and by a peculiar usually called medially divided sterna, e.g. Jordan,
differentiation of its hind margin. The ventral wall of 1909:330).EachanteriorscleriteCP8is,bythemem-
foldvf7issclerotizedbytheposteriorportionofCS7. branouslinec,almostcompletelydividedintoalarger
Its dorsal wallis likewise sclerotized by CS7since as caudalportionCX8andasmallercranialportionLC8.
intheprecedingsegmentsthecuticlebendinganteriad Each posterior sclerite CX9 has a small sclerite LC9
from the hind edge of the fold is sclerotized. The in front of it (Fig. 6), and both sclerites together are
sclerotization is mostly continuous around the edges comprisedhereassclerotizationCP9.CX8articulates
of the subgenital fold. In the middle part of fold vf7 posterolaterally with CX9 and extends medially onto
thedorsalandventralsclerotizationsstickquitefirmly a lobe gp8 flanking the genital opening. Of LC8 the
toeachother,thuseliminatingthebodycavitybetween lateral part extends onto an apodeme at8, and the
them. median part constitutes a long ribbon-like sclerot-
The right side of the subgenital fold has a deep ization. Sclerite CP8 has a 3-armed cuticular ridge.
incision il, around which the cuticle is strongly The posterolateral arm targets the articulation with
thickened(il=proximo-lateralsulciformimpressionin CX9; the posteromedian arm supports lobe gp8; the
Rehn & Rehn, 1935). On the left side cuticular thick- anteriorarmcrossesthenarrowmembraneseparating
enings occur in the corresponding area but are less the sclerite portions CX8 and LC8 and strengthens
extensive.Theextensionofthethickenedareasshows the median ribbon-part of sclerotization LC8. This
on both sides some variation. The semicircular post- latterpartoftheridgeiscalledheremt8.Eachsclerite
eromedian part of fold vf7 has two hind edges one CX9 has a strong median part and a weak lateral
above the other (ei, es in Figs 3, 4; ei=submarginal extensionfusedtotheventromedianmarginsofterga
258 K.-D.KLASS
Figures3,4. ExoskeletonofventerVII.Fig.3.DorsalviewofcoxosternumVIIandassociatedcomponents.↑anterior.
Sclerotizationdark.AnteroventralpartsofsegmentVIIIincludedonrightside.Cuticularridges/thickeningsindicated
by hatched stripes/areas. Dashed line: inferior hind edge of subgenital fold. Undulate lines: cutting lines through
cuticle. Scale bar=0.5mm. Fig. 4. Hind edge of subgenital fold. Left view of longitudinal section. Sclerotized cuticle
dark;bodycavitywhite.↑dorsal,→posterior.Noscale.
IX and X (area b in Figs 5, 6). Cuticular thickening ExoskeletonofsegmentsXandXIandtelson
establishes an oblique ridge on the median part of
TergumTG10isverylong(Figs6,22).Itisanteriorly
scleriteCX9andoccupiestheentirelateralextension.
overlappedbyandimmovablyassociatedwithTG9in
The area median and posterior to CX9 forms a broad
the way explained above (Fig. 10). Posterior to the
lobegl9.BetweenCX8andCX9originatesanapodeme fusion area b of sclerites TG9, TG10, and CX9 lies
at9, which bears the small sclerite LC9 in its dorsal the triangular sclerite LP, which is separated from
wall. TG10 by a narrow membrane (Figs 5, 6). Median to
SpiracleVIIIsi8hasthesamestructureandrelative LP arises the subanal lobe sb, which bears a weak
position as the more anterior spiracles (Fig. 6). Seg- sclerite AP on its posterior face. The anus an lies
mentIXhas,asinotherinsects,nospiracle.However, between the two subanal lobes. The rectum re has a
ithasinthecorrespondingposition,inthemembrane narrowterminalportion(Fig.6)andwidensinternally
between tergum and coxosternum, a minute brown intoabulbbearingthesixrectalpapillaerp(Fig.12).
spot si9 (Fig. 5). This appears in cross-section as an SegmentXhas,likesegmentIX,oneachsideabrown
invaginationoftheexternallayerofthecuticle,which spotsi10neartheventromedianmarginofthetergum
is internally entirely embedded in the thick internal (Fig.5).Itappearsincross-sectionasaninvagination
layer of the cuticle and thus not perceptible as an of both the external and internal layers of the cuticle
invagination from within (only external layer of this (Fig. 11), thus being also from within perceptible as
area depicted in Fig. 6). an invagination (Fig. 6).
The lateral and common oviducts (ol, oc in Figs 5, TheterminalscleriteTG11+DT(Figs5,6),shaped
6) are, due to the viviparity, very wide. Figures 5, 6 likeaposteriorlytaperingbag,formsamassiveprocess
do not show that the oviduct walls are longitudinally tf. This seems to be the posterior tip of the abdomen,
folded all over, the folds being a reservoir for much which, however, is in the morphological sense con-
further expansion of the ducts. The gonoduct opens stitutedbytheanusan. ScleriteTG11+DTandpro-
between the lobes gp8, and the transverse fold go is cess tf are thus entirely dorsal components. At its
the anterior border of the genital opening. dorsal anterior margin (Figs 5, 12, 22) TG11+DT is
ABDOMENOFH.VOSSELERI 259
Figures 5, 6. Exoskeleton of postabdomen, segments VIIIff. ↑ anterior. Sclerotization dark. All cuticular parts of
lateral oviducts included; cerci cut; only external cuticle layer considered for terga VIII to X (compare Fig. 10).
Cuticularridges/thickeningsindicatedbyhatchedstripes/areas.Undulatelines:cuttinglinesthroughcuticle.Sclerites
CX8+LC8=CP8;CX9+LC9=CP9.Scalebar=0.5mm.Fig.5.Ventral,predominantlyexternalview.Onleftsidelarge
parts of venters VIII and IX removed. Fig. 6. Dorsal, predominantly internal view. Rectum cut close to anus. Cercal
apodememacutonleftside(cutthroughmassivecuticle).
fusedtoandlevelwithtergumTG10nearthemidline Dorsolaterally the cercal base bears three delicate
but free from TG10 and narrowly overlapped by it cuticular tendons ct. The cerci are long and thread-
morelaterally(folddf10inFigs5,6,8).Atitsventral like.IconcurwithPopham(1985:204,fig.8)thatthey
anteriormargin(actuallyitsposteriormargin;Figs5, may appear to be, but are not, divided into articles:
6)TG11+DThasawidesemicircularrecess,withthe the cuticle, very thick considering both external and
sclerite’s rim somewhat overfolding the membrane in internal layers, is uniformly weakly sclerotized all
the recess. As mentioned above, this rim fits into alongthecerci,withoutannularmembranes,andwith-
the groove between the hind edges es and ei of the out complete annular grooves.
subgenital fold.
The bases of the cerci ce are located beneath the
lateral hind margin of tergum TG10 (Figs 6, 22); MUSCULATUREOFHEMIMERUS
ventrally they are in contact with sclerites LP and
TG11+DT (Fig. 5). The cercal base is firmly held Extentofmusclestudies
in between these three sclerites but has no distinct Ofthemusclespresentintheabdomenfromsegment
articulation with either of them. Basally the cercal IVononlytheintrinsicmusclesoftheoviductsandof
wallsprojectintothebodycavity,formingaU-shaped therectum(exceptmuscle51)arenotconsideredhere.
infolding (U open laterally; Figs 6, 8, 9). Its median The alary muscles were, due to the condition of the
portion, projecting most deeply, is termed here apo- specimens, difficult to examine. Those of segments
deme ma. Only on the distal part of ma the cercal VIII–X were not found, probably overlooked. Nutting
sclerotizationCEenterstheouterwalloftheinfolding. (1951: 530) indirectly reports these for Hemimerus
260 K.-D.KLASS
vosseleri, saying that all species he studied have 10
abdominal pairs.
MusculatureofsegmentsIV–VI
Themusculaturewasfoundidenticalinthesesegments
(Fig. 2). Homodynamous muscles are described and
numbered together. Each insertion is assigned to the
secondary segment it lies upon: ‘N’ designates the
secondarysegment,oracomponentofit,whosemajor
part corresponds to the primary segment the muscle
belongsto.‘N+1’designatesthesucceedingsecondary
segment, or a component of it. Muscles having both
insertions on ‘N’ are intrasegmental, muscles having
one insertion on ‘N+1’ are intersegmental relative to
secondary segmentation.
1: Tergum N, lateral part↔Coxosternum N, lateral
part. Intrasegmental tergo-coxosternal muscle. One
strong, compact bundle. 2: Tergum N, lateral
part↔Pleural membrane above coxosternum N. In-
trasegmental tergo-coxosternal muscle. One small,
compact bundle. 3: Tergum N, lateral part↔Coxo-
sternum N, lateral margin. Intrasegmental tergo-
coxosternal muscle. One small, compact bundle. 4:
Tergum N, far lateral part↔Coxosternum N, lateral
margin. Intrasegmental (para)tergo-coxosternal
muscle. One small, compact bundle. 5: Tergum N,
anterolateral part↔Tendon lt N. Intrasegmental
tergo-coxosternalmuscle.Onestrong,compactbundle.
6:TergumN,lateralanteriormargin↔CoxosternumN,
anterolateral corner, on apodeme at. Intrasegmental
tergo-coxosternalmuscle.Onemoderatelystrong,com-
pact bundle. 7: Tergum N, anterolateral cor-
ner↔Pleural membrane forming external face of
apodemeatofcoxosternumN.Intrasegmental(para)-
tergo-coxosternalmuscle.Onemoderatelystrong,com-
pactbundle.8:CoxosternumN,lateralpart↔Tergum
Figures 7–11. Details of exoskeleton of postabdomen.
N+1, anterolateral corner; partly on adjacent mem-
Sclerotizationdark.Fig.7.Dorsal,predominantlyinternal
brane and on a small membranous tendon. Inter-
view of area around genital opening. Representation as
segmental coxosterno-(para)tergal muscle. One
inFig. 6but manypartsremoved, inparticularthose of
gonoducts. Scale bar=0.5mm. Figs 8, 9. Exoskeleton of moderately strong, compact bundle.
cercal base area. Ventral view of right cercal base. ↑ 9: Coxosternum N, anterior margin↔Coxosternum
anterior,→median.Cuticularthickeningsnotconsidered. N+1, anterior margin. Internal ventral muscle. One
Undulatelines:cuttinglinesthroughcuticle.Scalebar= strong, compact sheet. 10: Coxosternum N, anterior
0.5mm.Fig.10.TergaVIIItoX.Rightviewoflongitudinal part↔Coxosternum N+1, anterior margin, and in-
section near dorsal midline, schematic. ↑ dorsal, → an- tercoxosternal membrane. External ventral muscle.
terior. External and internal layers of cuticle included. One strong, compact sheet. 11: Tergum N, anterior
External layer: narrow interspace, partly melanized= margin↔TergumN+1,anteriormargin.Internaldor-
filled black (TG8–10). Internal layer: broad interspace, salmuscle.Onestrong,compactsheet.12:TergumN,
entirelyunmelanized.Noscale.Fig.11.‘Spiraclevestige’ anterior part↔Tergum N+1, anterior margin, and,
X si10. Section in median view, schematic. ↓ ventral, → predominantly,intertergalmembrane.Externaldorsal
posterior.Externalandinternallayersofcuticleincluded. muscle. One strong, compact sheet. 13: Tergum N,
External layer: narrow interspace. Internal layer: broad lateralanteriormargin↔TergumN+1,anteriormar-
interspace.Noscale.
gin. External dorsal muscle. One moderately strong,
compact sheet. 14: Tergum N, anterior part↔Tergum
N+1,lateralanteriormargin.Externaldorsalmuscle.