Odonatologica38(4):369-374 December I,2009 Description of thelast instar larva of Hylaeothemis clementia Ris from Laos (Anisoptera: Libellulidae) A.Sasamoto¹and I.Kawashima² 1190-4Yakuoji,Tawaramoto-cho,Shiki-gun, Nara,636-0341,Japan [email protected] 2 1-50-9Nagasawa,Yokosuka-shi,Kanagawa,239-0842,Japan [email protected] ReceivedMay26, 2008/RevisedandAcceptedJune25, 2009 Thelarvaisdescribed andillustratedforthefirsttime,based onthelastinstarexu- viae. Itiscomparedwith theknown Tetrathemistinae larvaeand appearssimilar to theAfrican NeodythemisratherthantotheAsianmembers ofthe subfamily. INTRODUCTION ThegenusHylaeothemis R1S, 1909isplacedintheTetrathemistinae,whichwas foralongtimeconsideredaprimitive groupintheLibellulidae, based mainly on wingvenation(FRASER, 1957). Recently, inhisstudyoftheAfricanrepresent- atives, VICK(2000) hasshown thephylogenetically heterogenous nature ofthis subfamily. Hylaeothemiscontainsfourknownspecies; threeoftheseoccurinIndiaandSri Lanka, whereas H.clementia, arareandlocalspecies, was sporadicallyrecorded from Borneo, PeninsularMalaysia, Vietnam, Thailandand Laos.ASAHINA& KITAGAWA (1992) noted afewminormorphological differencesbetweenthe Borneanand Thaispecimens. From Laos, the species was forthe first timere- ported by YOKOI (2000), whoprovided also somenotes onitshabitatand ovi- position behaviour. Thefirstauthorhada chanceto visitYokoi’ssite at Phatan,centralLaos, and recovereda living larva, thatwas subsequently rearedto theadult.Thehabitatis asubmontanehumidforests, wheremales are holding territories atmuddy and grassyplaces, withaweakbutaconstant watercurrent,and somesunshineper- 370 A.Sasamoto& I.Kawashima trading through thefoliage. Thelarvawas locatedinmuddy andalmoststagnant water, downstreamofthemaleterritories. Nolarva ofany Hylaeothemis species was sofar described. HYLAEOTHEMISCLEMENTIA RIS (Figures1-6) Material. - 19 exuviae(driedandpinned),Laos:Vangviengdistr.,Phatang(19°10’N,102°27’E, alt.ca330m a.sl,larva collected20-IV-2002,adultemerged28-IV-2002,A.Sasamoto leg.&bred. Coloration. - Body ingeneral appearanceunicoloured,almost buff,in darkerparts faintlyyellowishorreddishtinged. Head, thorax, wingsheaths, legs andabdominaltergabuff, butthelatterratherpaleand translucent; ventral sur- face buff,paler thandorsal surface; cerci dark, tinged reddishbrown; epi- and paraproctsapices also tinged reddishbrown. morphology. — Generalshape elongateandslender, appendages moderate- ly longand robust. Body surfacefairlysmoothandshiny, with scarce setae and spines. Head. — Headcapsule (Figs 1, 3)ratherlargeandtransversely rectangular, clearly widerthan prothorax, andslightly narrower than pterothorax; dorsum weakly depressed. Antennae(Fig. 2)7-segmented, filiform,almostaslong as the length of headcapsule; relative length of eachantennalsegment fromscapeas follows: 1.00: 1.10:2.00: 1.10: 1.15: 1.40: 1.50;scapeshortandthickcylindrical; pedicel ratherelongate andcylindrical, alittlelonger than scape;basalflagellar (3rd) segmentthelongest, twiceas longas scape;5th flagellar(7th terminal)seg- ment elongate, spindle-shaped withsharply pointedapex.Compound eyes (Fig. 1) rathersmallandroundedindorsalview,not muchexpanded laterad, theirlength clearlyshorterthanthatofpostocular lobes.Postocularlobes(Figs 1,3)furnished withscatteredspinesandwithshortsetae scatteredon dorsalsurface; dorso-pos- teriorareas each withfive longitudinal glabrous areas; bothhindangles evenly round.Labrumshortandtransversely pentagonal, 0.4timesaswideasmaximum widthofheadcapsule; lateralmarginsalmoststraight onbasal2/5, divergentan- teriadandclearlyconstrictedatthebasalpart, forming acomerandthenabruptly convergenttowardstheanteriorshallowcorners;anteriormargin feeblyarcuate, very shallowly concave inits centralpart. Anteclypeus shortandtransverse,al- most as long as labrum; thesurface glabrous andsmooth; sidemargins weakly arcuate, directlyconnectedtoroundedanteriorcorners. Labium(Figs4,5)deeply cup-shaped as a whole, relatively largeand wide; the posterior marginof hinge betweenprementumandmentum reaching hindmarginal levelofforeleg coxae inthefolding situation; prementum0.8timesas wideasmaximumwidthofhead capsule; anteriormarginofprementumtriangular, pointed anteriorlyatthecen- LarvaofHylaeothemisdementia 371 tre; the central part as a comer,regularly scattered withminutesetae;normal premental setae absent, but with a pair of series ofminutesetae inthecen- tral part, half-length of prementum; laterallobes large and triangular; in- ferior margins slightly curved,roughly scattered with minute setae; distal margins almost straight, but forming shallow ser- rae,eachwith9 very flat- tened teeth, each with 1 to 3 short setae; lateral setae completely absent, a longer seta nearmova- blehooksondorsal(exte- rior) margins only; mov- able hooks rather short Fig. 1.HylaeothemisclementiaRis,lastinstarlarva(exuviae),dor- and slender, slightly in- salview. — [Scale: 2.5mm] curvate, sharply pointed atapex,antero-posteriorly moreor less depressed, ap- pearing blade-likeas a whole;exteriorborders0.3 timesas long as theexterior margins oflaterallobes. Thorax(Fig. 1). — Relatively large andwide; pronotumrelatively large, transversely spindle-shaped, rounded atbothsides; sides hardly bulged laterad; dorsal surface widely glabrous; longer setae and/orbristles arising at theposte- rior angle areas to posterior margin. Pterothorax(meso- + metathorax) large, slightly widerthanthemaximum widthof headcapsule, almost smooth, witha fewlongerhairsandsetae only. Wingsheaths(Fig. 1)parallel,elongated behind; hind wingsheaths 2.5 timesas long as wide; apices exceeding half-length of the 5th abdominalsegmentinexuviae. Legs (Fig. 1)ratherlongand robust; apices ofhind femorareaching the half-length of6thabdominal segmentin exuviae; tarsalformula3-3-3; 1sttarsomeres usuallytheshortest, obliquelyarticulatedto 2nd; 3rdusually thelongest, almostas long as thetotallength ofthe preceding twotarsomeresinfore-andmidlegs combined, whileclearly shorterthanthecor- responding length inhindlegs. Clawssmallandsimple. Abdomen(Fig. 1). - Elongate oval, weakly dilatedto thewidest6thseg- ment,andthen,gradually narrowedtowardsthedistal 10thandtriangularsmall periproct;eachsegmentrectangular indorsalandventralviews; lateralanddor- 372 A.Sasamoto& I.Kawashima sal spines completely ab- sent; surface of abdomi- nal terga rather smooth and weakly shiny, only minutespines, and short and longer setae appear along posterior margin ofeachtergite;setae aris- ing from the central ar- eas especially long. Val- vulavulvaevestigial, as a pairofminutelobesbare- ly seen between 8th and 9thabdominalsegments. Periproct (Fig. 6) rather short andthick; triangu- lar as a whole, 4.5 times as long as the length of the 10th abdominalseg- ment; epiproct (Fig. 6) elongate triangular with sharply pointed apex, clearly shorter thanpar- aprocts; dorsal surface rather smooth, scattered with minute, thin se- tae; both sides gradually convergent distally, and then, abruptly narrowed indistaltwo-third;parap- Figs2-6.HylaeothemisclementiaRis,lastinstarlarva(exuviae):(2) rocts(Fig. 6)pointedand rightantenna; - (3)headcapsule;- (4)apicalportionoflabium, showingprementum,leftlaterallobe andmovable hook,lefthalf; weakly curvedoutwardly —(5)distalmarginofleftlaterallobe; —(6)periproct,dorsalview. in distal2/3;exteriorand —[Scale:0.5 mm (Figs2,4&5); 1.0mm (Figs3,6). innermargins not serrat- ed; exterior surface with ratherlong setaeandhairs. Cerci(Fig. 6)ratherlong andthick, sharplypointed andfeeblycurved outwardly atapical section,0.50timesaslong as thelength of epiproct, and0.44timesas longas the length ofparaprocts. Measurements (inmm). - Bodylength(fromanteriormarginoffrontal areatoepiproct apex) 15.45;maximum head width(acrosscompoundeyes) 3.60;maximum pronotum width2.40; maximum abdomen width (on6th segment)3.80;hindwingsheaths length(on uppermargin)4.40; hind tibia length(onuppermargin)3.90. Larva ofHylaeolhemisdementia 373 DISCUSSION Thelarval morphology of Hylaeothemis clementiais characterisedby thefol- lowing features: (1) relatively small compound eyes, (2) anteriormarginof pre- mentum abruptly produced as anobtusecorner, (3) whilethenormalpremental andlaterallabialsetaeare absent, thereare only minutemarginal setae,(4)shal- low serraeandflattenedteethonthedistalmarginsoflaterallabiallobe, (5)rather hairy abdomen, andby (6) theabsence ofabdominaldorsalandlateralspines. Thelarvae ofonly afewrepresentatives oftwo Tetrathemistinaegenerawere sofardescribedfrom Asiaand Australia, viz.: Tetrathemis i. irregularis Brauer (NEEDHAM & GYGER, 1937), T. i. cladophila Tillyard(THEISCHINGER & HAWKING, 2006), T. platyptera Selys (M.A. LIEFTINCK, inVAN TOE, 1992), Nannophlebia risi TILLYARD(1913), N.buruensisLIEFTINCK(1930). General featuresof the Australian Nannophlebia larvae were summarized by THEISCHINGER& HAWKING(2006). All,“tetrathemistines” (sensu DIJK- STRA & VICK, 2006) larvaehaveseveral long andlaterallabialsetae and ab- dominaldorsal spines (that varyper species) and lateralspines on the 8thand 9thsegments. TheabovefeaturesseparateH.clementiafromtheknownalliedgenera,towhich it is only distantlyrelated. Surprisingly, the Hylaeothemis larvalmorphology appears similar to thatof theAfrican Neodythemis. Thelatter,and Micromacromia, endemicto tropical Africa,wereshownto representa monophyletic group,calledthe“neodythemis- tinegenera” (DIJKSTRA& VICK,2006). ThelarvaeoftheMalgasian N. hilde- brandtiKarsch andtheCameroonianN. afra(Ris) were describedby BUTLER etal.(2006). Based ontheirdescriptions, Hylaeothemis resemblesthe two Neo- dythemisspecies by havingrelatively smallcompound eyes, two rows ofminute setae aroundthecentre ofprementum (without the normallong premental se- tae),shallowcrenulationsonthe distalmargins ofthe labiallaterallobe, rather hairyabdomen, anditislacking theabdominaldorsalandlateralspines. H. clementiacan beseparated fromN. hildebrandtiby theabsence ofthe lat- erallabialsetae andbytheratiosoftheantennalsegments,andfromN afra by thearrangementof the minutesetae in the centre ofprementum,therat.ios of antennalsegments,the moreroundedposterior corner ofthe head, andby the ratherthick periproct. Based on the shape of the genital hamulus, RIS(1909) already noticed the affinities between Hylaeothemis and the “neodythemistines” Allorhizucha, Mi- cromacromiaand Neodythemis. DIJKSTRA & VICK (2006) also emphasized thesimilaritiesinthegeneral appearanceandhamulusstructure intheadultsof thesetaxa. 374 A.Sasamoto& I.Kawashima ACKNOWLEDGEMENTS We wishto expressourcordialthanks toDrN.YOKOIforhiskindsuggestionsrelative tothefield work and toMessrs V.SOUPHANTHONGand T.HONDAfortheirsupportinthefield. REFERENCES ASAHINA, S.&K. KITAGAWA, 1992. Anewaddition totheodonate faunaofThailand. Proc. JpnSoc.syst.Zool.47:33-36. BUTLER, S.G., D.G.CHELMICK & G.S.VICK, 2006.Descriptions ofthe lastinstar larvae of Neodythemishildebrandti Karsch andN. afra(Ris) withcommentsonthestatus ofthege- nusandsubfamily (Anisoptera:Libellulidae).Odonatologica35(3):233-241. DAVIES,D.A.L.&P.TOBIN, 1985. Thedragonfliesoftheworld: asystematiclist oftheextantspe- ciesofOdonata,Vol. 2:Anisoptera.Soc. int. odonatol. rapidComm. (Suppl.)5: 1-151. DIJKSTRA, K.-D.B.&G.S.VICK, 2006. Inflation byvenation and thebankruptcy oftraditional genera:thecaseof Neodythemisand Micromacromia with keys tothecontinental African species andthe descriptionoftwonewNeodythemisspecies fromtheAlbertine Rift(Odo- nata:Libellulidae).Int.J. Odonatol. 9(1): 51-70. FRASER,F.C., 1957. Areclassificationofthe order Odonata. R.Zool, Soc.N.S.W.,Sydney. NEEDHAM, J.G.& M.K.GYGER, 1937. TheOdonataofPhilippines.Philipp. J. Sci.63:21-101, 10pis., 2figsex. LIEFTINCK,M.A.,1930.FaunaBuruana Odonata,3:areview ofthedragonfly-faunaofBoeroe, inthe Moluccas,withdescriptionsofneworinterestingspecies,andanaccountoftheirlar- vae.Treubia7(Suppl):305-330,9plsexcl. RIS,F., 1909. Libellulinen monographischbearbeitet,1.Colins zool. Edm. deSelysLongchamps9: 1-120,1pi.excl. THEISCHINGER, G. &J.HAWKING, 2006. Thecompletefieldguidetothe dragonfliesofAus- tralia. CSIRO, Sidney. TILLYARD,R.J., 1913.Description andlife-historyofanewspecies ofNannophlebia.Proc. Linn. Soc.N.S. W.37(4):712-726,pi.74. VAN TOL, J., 1992. Anannotated index tonamesofOdonata used inpublicationsby M.A.Lief- tinck.Zool. Verb. 279: 1-263. VICK,G.S., 2000. Mesumbethemis takamandensis gen. nov.,spec, nov., a newgenus and species oftheTetrathemistinae fromCameroon,with akey totheAfrican generaofthesubfamily (Anisoptera;Libellulidae).Odonatologica29(3):225-237. YOKOI, N., 2000.[Alist ofdragonfliescollected in Central Laos].Gekkan-Mushi 356: 18-22. [Jap, with Engl,s.]