Description of the last larval instar of Epophthalmia vittata cyanocephala Hagen, 1867 (Anisoptera: Corduliidae)

5 Pages·2000·0.87 MB·English

by  Bedjanič, M

Odonatologica29(1): 57-61 March 1.2000
Description of thelast larval instar of
Epophthalmia vittata cyanocephala Hagen, 1867
(Anisoptera: Corduliidae)*
M. Bedjanič
Fram 117/a,SI-2313 Fram, Slovenia
Received May 19,1999/RevisedandAcceptedAugust4, 1999
The ultimate instar larva is described and figuredfrom exuviae, collected near
Anuradhapura,Sri Lanka. Our present knowledgeofthe larval forms ofthe genus is
briefly discussed.
INTRODUCTION
The genusEpophthalmia Burmeister comprises the eleventaxa ofwhich E.
biosdinataLewis, 1969isknown only from afossilrecord while otherten mem-
bers are distributedthroughout southern and eastern Asia (Tab. I). Although the
representatives ofthegenusEpophthalmia are very large andconspicuous insects,
they are ratherpoorly represented incollectionsand some ofthem arevery inad-
equately known. This is particularly true forthe larval stages towhich very little
attentionhas beendevotedinthepast. They are characterizedby very long legs, a
smallrectangular headwithtwolatero-posterior projections andsmallpointed eyes
as wellas by abroadly ovalabdomenwithstrongdorsal spines. Of special interest,
however,is theverybig andspecialized labiumwithpeculiarly shaped labialpalps,
which appears tobe unique inthewholefamily Corduliidae.
In the detailedrevision ofthe genusEpophthalmia, produced by L1EFTINCK
(1931), the authoralso summarized all published information on the larval
features of representatives ofthat genus and described the last larval instars
of three species, viz. E. elegans, E. vittigera and E. vittata vittata. Apart from
E. elegans whichhas been studied indetail andis well known (ISHIDA, 1996),
the two other descriptions are based on very limited numbers of larvae or
*Dedicated to ProfessorDrGerhardJURZITZA,ontheoccasion ofhis70lhbirthday.
58 M. Bedjanic
exuviae, which were not rearedto metamorphosis or taken during emergence.
Also in Epophthalmia vittata cyanocephala, which is endemic to Sri Lanka,
larval stages and exuviae have not been described previously. Unfortunately,
the present description is based on a single larval skin, without definite
association with the adult stage. According to the fact that the subspecies is
confinedto Sri Lanka and at the same timeis the only representative of the
genus on the island the determination is not doubtful, yet it makes any
comparison and differential analysis with other taxa almost impossible.
Table I
Extant representatives ofthe genus Epophthalmiawith their known distribution range — [Taxa in
which last larvalinstars havebeen describedareasterisked[
SSppeecciieess DDiissttrriibbuuttiioonn
aauussttrraalliiss HHaaggeenn,, 11886677 IInnddoonneessiiaa ((CCeelleebbeess,, MMaalluukkuu))
** ee..eelleeggaannss((BBrraauueerr,, 11886655)) CChhiinnaa,, JJaappaann,.HHoonnggKKoonngg,.TTaaiiwwaann
ee..yyaaggaassaakkiiiiEEddaa,, 11998866 NNoorrtthhKKoorreeaa
f/..frforonnttaalliiss SSeellyyss,, 11887711 IInnddiiaa((AAssssaamm,,wweesstteerrnnHHiimmaallaayyaa)),,TThhaaiillaanndd,,MMaallaayyssiiaa
ff..bbiinnoocceellllaattaa((FFrraasseerr,, 11992244)) IInnddiiaa((WWeesstteerrnnGGhhaattss))
** vviittttaattaa vviittttaatlaaBBuurrmmeeiisstteerr,, 11883399 IInnddiiaa((PPeenniinnssuulalarrIInnddiiaa.,UUttttaarrPPrraaddeesshh,, WWeessttBBeennggaall))
** vv..ccyyaannoocceepphhaallaa HHaaggeenn,, 11886677 SSrriiLLaannkkaa
vv..ssuunnddaannaa LLiieeffttiinncckk,, 11993311 IInnddoonneessiiaa((eeaasstteerrnnSSuummaattrraa,,WWeesstt&&CCeennttrraall JJaavvaa)),,VViieettnnaamm
** vviittttiiggeerraavviittttiiggeerraa((RRaammbbuurr,, 11884422)) IInnddoonneessiiaa((BBaannggkkaa,, BBiilllliittoonn,, JJaavvaa,, BBaallii,, BBoorrnneeoo)),,MMaallaayyssiiaa,,
SSiinnggaappuurr,,tthhee PPhhiilliippppiinneess
vv.. bbeelllliiccoossaaLLiieeffttiinncckk,, 11994488 IInnddiiaa((eeaasstteerrnnIInnddiiaa)),,MMyyaannmmaarr((BBuurrmmaa)),,TThhaaiillaanndd,,VViieettnnaamm
DESCRIPTION
Material.— 1ex.(6);Watertank700mSEoftheAbhayagiriDagoba,Anuradhapura,Anuradhapura
District, NorthernCentral Province,SriLanka, 19-1-1995, alt. 100m;M.BedjaniCleg.& det.Material
is depositedinauthor’sprivate collection.
Head. — In general appearance it agrees well with the detaileddescription
provided by LIEFTINCK (1931). Eyes in the latero-anteriorcomer ofthe head
smallandprominent, directed upwards. Twoprojections on dorsallatero-posterior
part directedbackwards, following theimaginary diagonal to the eye onopposite
side ofthehead. On the lateralsurface, belowtheprojection, two fields ofsmall
thinsetae. Betweenbasesofantennae ashortmedianprocess thatreaches themid-
dleoffirst antennaljoints. Anteriorpart prominent, gradually flattenedtowards
posterioredge, whichends attheanteriorpartofocelli.Prominentanteriorpartof
medianprocess semicircular, flattenedfrontally, with dorsaledge slightly thicker.
Withthe exception offirst segmentsantennae broken.
Labium very big, with peculiarly shaped labial palps (Fig. 1). Viewing
laterally, mask very flattened with labial palps curved upright following the
Larva ofEpophthalmiavittata cyanocephala 59
shape of the head. The articulation between prementum and postmentum
reaches distally the middle of metathoracic poststernite and coxae of
metathoracic legs respectively. Labial palps and prementum (basal part and
articulationprementum-postmentumnot indicated) are shown in Figure 1. On
the left labialpalp fourth hook the longest, sixth the shortest and on theright
labial palp fifth hook the longest, first three hooks being the shortest. Apical
halves ofhooks black.
Legs. — Very long, coxae ofprothoracic legs and apical halfof coxaeof
mesothoracic legs overgrown with longer hair-like setae, coxae ofmetathoracic
legs sparsely overgrown withshortersetae. Lateraledges ofthoracicbasisternites
withtuftsoflong hair-like setae.
Abdomen. — Very large, oblonge, abdominalsegments S5-S7the broadest.
VentralsurfaceofabdominalsegmentsS1-S8very poorly setose,posterioredge of
S9withgenerally sparselongerhair-likesetae,whichare thelongest onthelateral
fringeandreach halfof S10in length. Ventral surface of S10laterally overgrown
withvery shortsetae,whichcover alsothe ventralsurface ofparaprocts,between
whichlong hair-like setae outgrow. Dorsal surfaceofabdomenin surrounding of
mid-dorsalhooks andposterior edges ofsegments overgrown with very small
spiniform setae. Lateral margins ofabdomenovergrown with short strong setae.
Between these, on abdominal segments S6-S9, much longer hair-like setae out-
grow,being mostbushy apically. Mid-dorsalhooks onsegments S4(?)-S9, S3 with
only small pointed protuberance, lateralspines on segments S8-S9(Figs 2 and 3).
Analpyramid atriflelonger thanabdominalsegmentS10,paraprocts being thelong-
Figs 1-3.EpophthalmiavittatacyanocephalaHagen,larval structural features: (1) prementum (with-
outbasalpart) and labial palps,dorsal view; —(2) abdomen,dorsalview; — (3)abdomen,left lateral
view (dorsal spine(?)onabdominal segment S4broken).
60 M.BedjaniC
est, epiproct little shorter, cercithe shortest but almost as long as epiproct (Fig.
3).
Measurements (mm).— Body length: 31.5;abdomen length:21.5; abdomen width: 13.1;
lengthof 10th. abdominalsegmentinch analpyramid:2.9;tibia length(prothoracic,mesothoracic &
metathoracic leg):8.2,9.9, 13.0; femurlength(metathoracicleg): 12.2;labiumlength:9.9;prementum
length:6.1;prementum width: 5.3; moveable hook length: 1.0;lengthoflatero-posteriorhead-projec-
tions: 0.7.
DISCUSSION
Larvalformsoftherepresentatives ofgenusEpophthalmia areverypoorly known.
According toLIEFTINCK(1931) theknownlastlarvalinstarsarerathersimilarin
somecharacters, however,as already statedby himself, alittledoubtremainsas to
thecorrectness of descriptions since material usedin his study was not reared or
taken during emergence.In view ofourpresent knowledge on thedistributionof
Epophthalmia species thereare actually some problems. The description ofE. v.
vittatabasedon asingle larvacollected nearCalcuttainIndia, mayreferratherto
E. vittigerabellicosa, whichalsooccurs inthatregionandwas described later. Itis
also uncertainwhether description oflast larval instarofE.frontalis (FRASER,
1919) was correctly ascribedto E. v. vittataby LIEFTINCK (1931) and FRASER
(1936). Bothauthorsoverlookedinformationonthenumberof dorsal spines given
inFraser’s description, whichare statedtobe onthefifth toninthabdominalseg-
ments,whileinthe description of E. v. vittataLIEFTINCK(1931)dorsalspines in
this species are on thefourth to ninthabdominalsegment. The speculation that
FRASER(1919) actually describedthelastlarvalinstarofE.frontalisbinocellata
is thereforealso possible.
Although itisalmostimpossible andnotveryreasonabletomakeconclusionson
thebasisofsingle exuviae, there are someclear differencesbetween E. v. vittata
and E. vittata cyanocephala in the shape of the labial palps. In E. vittata
cyanocephala, the very long fourthand very shortsixth hooks ofthe left labial
palp are specific andshow cleardifferenceincomparison withE. v. vittatainwhich
fifthand sixthhooks onthe left labialpalp arethe longest (LIEFTINCK, 1931). It
can be immediately separated from E. elegans by the absenceofthewell devel-
oped dorsalspine onthethirdabdominalsegment(ISHIDA, 1996).Usefulcharac-
ters for distinguishing E. vittatacyanocephala fromE. v. vittigeraare diffentshape
of the labialpalps, the smaller latero-posterior head-projections and different
shape ofthe short median process between the bases of antennae. When the
shape of labial palps is concerned, it is worth mentioning that a study of a
dozenexuviae of E. v. vittigera, collected at RiamKannan Lake in Borneo,
revealedindividual deviation in theform ofthe labial palps, the shape ofthe
leftand right sides in some specimens being reversed.
Forthe analysis ofotherdifferentialfeaturesmuchmorematerialis needed,not
only inE. vittatacyanocephala, butespecially inthespecies with stillundescribed
Larva ofEpophthalmiavittatacyanocephala 61
last larval instars. Only then will a competent revision ofthe larval forms in
the genusEpophthalmia be possible.
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