Odonatologica31(4): 345-358 December 1,2002 NotesontheLibellago damselflies of theAndamanand NicobarIslands, with descriptionof anewspecies (Zygoptera: Chlorocyphidae) M.Hämäläinen DepartmentofAppliedBiology,P.O.Box 27,FIN-00014 University ofHelsinki,Finland e-mail; [email protected] ReceivedJanuary21, 2002/ ReviewedandAcceptedApril9,2002 Libellagoblanda (Hagen)andL. andamanensis(Fraser)areremovedfromsynonymy withL.lineata(Burnt.);theyareredescribed inbothsexesandcomparedwithL lineata. Recentlyacquired material fromthe Nicobar Isis (CamortaandGreat Nicobar)reveals thattheoriginaltypeseriesofMicromerus blandus consistsof2close,butdistinctspp.A 6 specimen(inZMUC)fromNancowryIsland isdesignatedasthelectotypeofblanda. Formersyntype 99 fromLittleNicobarbelongtoanewsp.,described hereas L. balus sp.n,,holotype(depositedatRMNH.Leiden)ofwhichcomesfromGreatNicobarIsland, CampbellBay area,24-XII-2000. 33 ofL.blanda andL. balussp.n. differinthecolour pattern ofabdomen and in the shapeofrhinarium. The status ofL. indica (Fraser) is brieflydiscussed. INTRODUCTION TheAndamansandNicobars,also called ‘TheBay Islands”, areremote islandsin the Indian Ocean. Especially the Nicobars, the southern group,where the Indian governmentdoesnotallowforeign visitors atall,is stillentomologically ratherpoorly known.Illustratingourlack ofknowledge is thefact thatLibellago blanda(Hagenin Selys, 1853),the firstodonatefrom these islands andthe secondin its genus tobe described,hasremainedperhaps thepoorestknownLibellago taxon. Ittookover 150 yearsbeforemorespecimens of itwere collectedinthe Nicobars. Duetothecourtesy of Dr PrashanthMohanraj andhiswifeDrK. Veenakumari,I havereceivedforstudyplentyofnewLibellago materialfromthearea.Alsopartofthe typeseriesofL.blandawas studiedandalectotype selected. 346 M.Hamalainen HISTORICALREVIEW Thefirstscientificinsectcollecting intheareatookplaceinJanuary-February 1846, whentheDanishcorvette “Galathea”visitedtheNicobarsduringitstwoyearexpedition aroundtheworld.Accordingtodatapresented by SCHI0DTE(1855),theentomologist oftheexpedition, Carl EmilKiellerup, collected atotalof78 odonate specimens representing 15 species from5 islands. These were sent for study to H.A. Hagen. Hagen’s brief original description ofMicromerusblandus appeared in SELYS LONGCHAMPS (1853). A more detailed description was given in SELYS LONGCHAMPS & HAGEN (1854), wherethe species was compared with itssole known congenerM. lineatus(Burmeister, 1839). FRASER (1924) provided the first treatmentofthe Andaman dragonfly fauna, reportingon 17specimens of9species collectedby N.AnnandalefromMtHarrietin the SouthAndaman Islandin November-December1923. Among the newspecies describedwasMicromerusandamanensis,basedononesingle malefoundatanaltitude of500ftona“rocky poolbelowwaterfall”on30November1923. FRASER(1924) didnotcomparehisandamanensiswiththe description ofblanda atall. Later FRASER (1928) wrote about blandaas follows: “I havenot seen this species, whichintheSelysian descriptionissaidtocloselyresemblelineata,afactthat leadsmetodescribeitas asubspecies ofthetypicalformfromJava”,i.e.asMicromerus lineatusblandus.AlsoinERASER’S(1934) “ThefaunaoftheBritishIndia”volume, blandawas treatedas a subspecies oflineata, butandamanensisas a good species. Theywere nowplaced inthegenusLibellago Selys, 1840.BothLIEFT1NCK(1932) and LAIDLAW (1950) listed these taxa with the same status as Fraser. However, Lieftinck atleast had not studied any material fromthe Andamansand Nicobars personally. CHHOTAN1 etal.(1983)describedthe firstfemaleofandamanensisfromSouth AndamanIsland. They downgraded andamanensisto a subspecies ofL. lineata (Burmeister, 1839), andthereafterbothblandaandandamensis havebeentreatedas ssp. of lineataby theIndianauthors(e.g. PRASAD& VARSHNEY,1995). Intherecent worldOdonatacatalogues, listing ofthese taxa hasbeenvariable.L. andamanensiswas listed as a good species by DAVIES & TOBIN (1984) and STEINMANN(1997), butas ssp.oflineatainBRIDGES(1994)andTSUDA(2000). L. blandawas treatedas a synonym of L lineata in DAVIES & TOBIN (1984), BRIDGES(1994)andSTEINMANN(1997),butas ssp.oflineatainTSUDA (2000). Apparently no dragonflytaxonomisthadstudiedanyofthesyntype malesofblanda afteritsoriginal description until now.Moreover,as bothHagen’s descriptions were somewhatincomplete (thecolourpattemoftheabdomeninadequately described) and FRASER’s (1928,1934)second-handdescriptivenotesrathermisleading,theexisting confusioninliteratureisunderstandable.Theholotype ofLandamanensis, originally placed in the Indian Museum, appears to be lost, but new specimens from the surroundings ofthetypelocality are available. ÜbellagooftheAndamanandNicobar Islands 347 MICROMERUS BLANDUS HAGEN inSELYS, 1853 — ACOMPOSITETAXON MicromerusblandusHageninSELYSLONGCHAMPS, 1853: 64-65 [orig. descr. of bothsexes]; - SELYSLONGCHAMPS&HAGEN, 1854:234-236,pi. 8,fig.14(details ofheadstructures),pi. 14,fig.7(maleabd. tipandappendages)[moredetailed descr.by comparingwithM. lineatusBurnt.]. Micromerusblandus:SELYSLONGCHAMPS, 1873:617(sep.p,64)[brieflycompared with M.semiopacusSelys]. Micromerusblandus:SELYSLONGCHAMPS, 1879:398(sep.p.52)[comparedwith M. sumatranusAlbarda]. Micromeruslineatusblandus: FRASER, 1928: 687 [second-handdescr.,downgraded tossp.]. Libellagolineatablanda:FRASER, 1934:60,65[keyed, second-handdescr.], Libellagol.lineata:DAVIES&TOBIN, 1984: 17[blandalistedasjuniorsynonymof lineataforthe firsttime]. TYPEMATERIALOFMICROMERUSBLANDUS. - SELYS LONGCHAMPS &HAGEN (1854; 236)state: “M.Hagenaexaminetrois malesdeNangkowryetquatre femelles dePetitNikobar”. Since onlytwomalesfrom “Nangkovri”andthreefemalesfrom“Nicobarmin”,[allhavinglabels“Micromerus blandusHag.”and “Hagendet.”] areavailable atZMUC (Copenhagen),Hagenhadapparentlyretained onespecimenofbothsexesforhiscollection.However,accordingtodatareceivedfromDrRosserGarrison, onlythefemalesyntype(Nr 12113)isnowavailableatMCZ(Harvard).Thewhereaboutsofthethird male isunknown. Itmay be lost; anywayit is notincoll. Selys atIRSN (Brussels),either. [In fact,SELYS LONGCHAMPS, 1879 wrote thathehas notseenthisspecieshimself].Surprisingly,in ZMUCthereis alsoan"extra”,somewhat differentlookingmalespecimenplacedunderthename”?blanda”from“Lille Nicobar” amongthe specimensbroughtby theGalathea expedition.Thisspecimenwasnotstudied by Hagen [nolabels by Hagenand notmentioned in SELYSLONGCHAMPS, 1854,norincluded in SCHI0DTE, 1855;tableonp. 112].Thus,itisnotasyntype. Oneoftheislandsfromwhichthesyntype seriesofM.blandusoriginates,Nancowry, belongs tothe’’MiddleNicobar”island-group, whereasLittleNicobarbelongs tothe southern’’GreatNicobar”-group.Theseislandgroupsareseparated by theSombrero Channel(275mdeep),whichalsokeptthemseparateduringperiodsofthePleistocene sealevellowerings (max. 160m) (seeRIPLEY& BEEHLER, 1989).Duetoalong isolationtherearecleardifferencesinthefaunaandfloraintheseislandgroups.Based ontherecently receivedmaterial, thisalsoapplies tothestream damselflies.Libellago malesfrom theseislandgroupsdifferto such anextent thatthepopulations mustbe consideredtorepresenttwo distinct species. Consequently, fromthe syntypes ofblanda, malesandfemalesbelong to different species. 1 preferto selectamalespecimen as the lectotype of Micromerusblandus. Fromthetwoavailablemalesyntype specimens, DrN.M.Andersen,SeniorCurator ofZMUC, sentthe betterpreservedmalefor meto study anditis designated as the lectotypehere. Lectotype(at ZMUC):male specimen bearingold, hand-written,white labels “Nangkovri” / “Micromerus blandus Hag. S”/“Hagendet.”/and amorerecent, hand-written,red label “TYPE, Micromerusblandus Hagen1854”.Ihave addedanotherred(printed)label“LECTOTYPE. Designated by M.Hamalainenin2001.PresentnameLibellagoblanda(HageninSelys, 1853)”.The lectotypelacks 348 M.Hamalainen therightforelegandbothmiddlelegs;otherwiseitisacompletematurespecimen.Pinnedwingsspread; colourswellpreserved;segments7-10andappendagesslightlymouldyabove,heavilysoontheunderside. Thesingle availablesyntypemalebecomes paralectotype.The specimen(atZMUC)bears similarold labelsasthelectotype.Accordingtodatagivenby DrN.M.Andersenits analappendagesarebroken,but otherwise itisacompletespecimen. This lectotype selection makes Nancowry Island[also calledNankamiIsland] the typelocalityofL.blanda.Theformersyntype femalesfromLittleNicobarbelongtoa newspeciesL. balussp.n. describedbelow. Fromthesesyntypes Ihavestudiedonly onefemalespecimen (ZMUC), which bearsold, handwrittenlabels’’Nicobarmin.”/ ’’Micromerusblandus Hag. 9 ”/’’Hagen det.” and amorerecent handwritten red label’’TYPEMicromerusblandusHagen 1854”.[Two similarly labelledfemalesare availableatZMUC; onefurtherfemaleat MCZ]. LIBELLAGOBLANDA (HAGEN inSELYS, 1853), STAT.REV. Figures 1-2,6, 13 Material. — Lectotype 8 fromNancowry Island(seeabove). — New material fromCamorta Island (allPrashanth Mohanrajleg.): —58,2$, Camorta,’’AgricultureDepartmentFarm”,9-1-2001; — 5 8,Camorta, Murak,8-T2001. — [1 8 depositedatRMNH, Leiden;most ofthe rest remainin author’s collection]. male (Lectotype). — Head. — Labiumblack.Rhinarium(ante-andpostclypeus) with anterior side shining black, withbrownish borders and with a distinctshining flattenedfacet;posteriorpartmattblack.Restoftheheadmattblack,withconspicuous orangeyellowmarkings asfollows: apairoflarge square-shaped markings infrontof antennae;smallrounddotsnear thelateralocelli, alittlelargerthantheocelli;arather broadbandalong occipital margin, anteriorly triangle-shaped inthemiddle. Prothorax black withorangeyellow markings asfollows:abroadhorizontal bandacross theanteriorlobe; abroadtriangle-shaped marking covering most ofthe posteriorlobe. Pterothorax black, withorangeyellowstripes and markings. Dorsal carina orangeyellow. Narrowantehumeralstripestaperingabove,notextending towingbase, wherethey continueas separate dots.Orange markings on metepistemum are quite similartothoseinLbalussp.n.(cf.Fig.9),butsomewhatsmaller;abroadmarking on metepimeron as inL.balussp.n.,somewhatobscuredapicad; ventralsideblack. Legs black, innersideoftibiaecreamywhite. Wings. — Hyaline, bases withoutyellow tint. Tip of forewing with large dark spot, quitesimilartoL.balus sp. n. (cf.Fig. 11), buttheapexof forewing somewhat moreabruptlyrounded.Theutmosttipsofhindwing obscurely darkened.Pterostigma present onlyinthehindwing. VenationdenserthaninL.lineata, resembling thatofL. andamanensisandL.balussp.n.(cf.Figs 10-12).Forewing with6antenodals.Hindwing with6 ante- and 14-15postnodals; pterostigma black, covering 4-5 underlying cells. Abdomen(Fig. 1). — Lessstrikingly dorsoventrally depressedthaninL. lineata, Übellagoofthe Andaman andNicobar Islands 349 S3-4onlyslightly broaderthanS2 and S5. Largely orange reddish aboveandonsides.S1broadlyblack at base; S2 with anteriorborder black,connectedtoabroadposterior black marking; paired middorsal black spots on S3-7,thoseon S3-4 fused together, getting smaller in apical segments. Intersegmental rings narrowly black, S8 broadly black posteriorly, S9-10 wholly black. Sl-2andbaseofS3broadly black lateroventrally, S4-8 only ventrolateraledges and sternites black. Anal appendages black, of typical shape for the genus. [According to Dr N.M. Andersen, intheparalectotype maletheblack marksonS4arenotfused;otherwise thecolourpattern ofabdomenis Figs 1-5. Male abdomen (dorsalview); — (I)Libellago similar]. blanda (lectotypefrom Nancowry); — (2) L. blanda Measurements (inmm). —Hind- (Camorta); — (3)L. balus sp. n.(paratypefrom Great wing20, abdomen(incl.appendages)16. Nicobar); — (4) L. andamanensis (SouthAndaman, Males from Cantorta. — Garacharma); — (5)L. lineata (Java,Bogor), Intwo specimens theupperorange marking onthemetepistemum is dividedintotwo parts atthenarrowest section.The blackabdominalmarkings (Fig. 2) aremorepronounced thaninthelectotype.SIand S2quitesimilarly markedtothelectotype,buttheblackareaisalittlemoreextensive. S3-7 with paired black markings, those on S3 fusedin all specimens, thoseon S4 fusedinafewspecimens andthoseonS5-7fused only inone specimen. Thepaired dorsalspots onS7are connectedto theapical black ring in allspecimens, in some specimens alsothoseon S5 andS6.In mostspecimens, the middorsalcarinaareais darkenedonS3-4, evenforming anobscure triangle withtheapical marking onS3. Abdominalsegmentsbroadly black lateroventrally, also inthe apical segments. The dorsalorangecolour protruding more ventradin basalhalfofS7-8.Usually 6(5-7) antenodalsinbothfore-andhindwing; 13-15postnodals inthehindwing. Pterostigma inhindwing covering 4(seldom5) underlying cells. Measurements (inmm). — Hindwing18-20,abdomen (incl.appendages) 14-15.5. female (first female). — Of the two availablefemalesfromCamorta, one is somewhatteneralandhasbecomeflattenedintheenvelope, the otheronehas been selected. They are slightly smaller, but quite similartothose ofL. balus sp. n. (see below). As inmales,thetriangularyellowishmarking onthehindlobeofprothoraxis smaller.Abdomenis quitesimilarlycolouredas inL.balus sp. n.femalesfromGreat 350 M.Hamalainen Figs6-9. (6-7)Profileofmalerhinarium,lateral view:(6)Libellagoblanda (Camorta); — (7)L. balus sp.n. (paratypefromGreatNicobar). — (8-9),L. balus sp.n. (paratypefromGreat Nicobar):(8)head, dorsalview;— (9)thorax,lateralview. Nicobar.However,theblackdorsolateralbandis slightlynarrowerandmoreundulating intheanteriorhalf(Fig. 13);inposteriorhalfwithout clearsign ofbecoming wholly indentedby theyellowcolouronS4-6.Abdomenventrolaterally broadly black,with onlytiny yellowishmarkings onS7-8. Measurements (inmm). — Hindwing18-19, abdomen 13. DISTRIBUTION. — Thisspeciesappearstobeconfinedtothe’’MiddleNicobar”group oftheNicobarIslandsandhassofaronlybeenrecordedfromNancowryandCamorta. Itmightalsooccurin Katchall, fromwhere apparently no dragonfly specimens have beencollected.Fromthethird(northern) islandgroup’’CarNicobar/Teressa”, which alsoremainedseparatefrom the other groups during periods ofthe Pleistocene sea lowering, noLibellago damselflieshaveyetbeenfound,but dragonfliesareknownto havebeencollectedso faronly inCarNicobar. FLIGHTSEASON. — Knownrecordsmade in January-February. LIBELLAGO BALUS SP. NOV. Figures 3,7-9, 11, 14 Libellagoaurantiaca[nec. Selys, 1859]:MITRA, 1995: 3[2 Srecorded from“Near Galathea”,GreatNicobar,3-VIII-1984]. Material. — Holotype6:GreatNicobar Island,”3.5 kmfromzeropointalongCampbellBay - GorindNogurRoad”, 24-XII-2000,Prashanth-Mohanrajleg.(DepositedatRMNH,Leiden).Paratypes: 66,49fromthesamesiteastheholotype,24/27-XII-2000,Prashanth-Mohanrajleg.; — 13, 1 2,Great Nicobar,CampbellBay, 18/19-XII-1996,K.Veenakumarileg.[1 9atRMNH,mostoftheotherparatypes placedinthe author’scollection].Other material studied: 1 3 [intheGalathea Expeditionmaterial atZMUC],furnishedwithanoldhand-written label“Lille Nicobar,Galatea”(seeabove); — 19 (ZMUC), ’’Nicobarmin.” [syntype ofMicromerusblandussensuHagen;seeabove]. Etymology.- Theearly ArabnavigatorscalledtheNicobarIslandsby thename’’Balus”.Theislands LibellagooftheAndamanandNicobarIslands 351 were also known tothem as’’Megabalu”,’’Legabalu”and"Nagabalus”(seeKLOSS, 1903).The species nameistobeconsidered asanouninapposition. MALE.— Head. — Labiumblack. Rhinarium(ante-andpostclypeus) with anterior sideshiningblack,withbrownishborders.Posteriorpartofrhinariummattblack.Rest of thehead mattblack, with conspicuous orangeyellow markings (Fig. 8): apairof large square shaped markings infrontof antennae;smallrounddotsnear thelateral ocelli, doublethesizeoftheocelli;aratherbroadbandalongoccipitalmargin,anteriorly triangle-shaped inthemiddle.Inteneralspecimens genae,baseofmandiblesandthe outersideofantennae pedicelpartly yellow. Prothorax black withorangeyellow markings asfollows:abroadhorizontal bandacross theanteriorlobe;half-moonshaped markingsonsidesofthemedianlobe; abroad triangle-shaped marking covering most ofthe posterior lobe. Tiny narrow markings ontheanterolateralcomers oftheposterior lobe. Pterothorax black, with orangeyellow stripes as inFigure9.Dorsalcarina orange yellow. Narrow antehumeral stripes tapering above, not extending to wing base, where they continue as separate dots. A narrow, short marking also atthe upperpart ofthe humeral suture. Metepistemumwith large markings; in some specimens theupperpart is dividedtotwo sections. A broad marking on metepimeron, somewhat narrowing apicad. Ventral side black. Legs black, innersideoftibiaecreamy white. Wings. — Hyaline, bases without distinct yellow tint. Tip of forewings withlarge dark spot (Fig. 11). Venation denserthan in L. lineata, resembling thatofL.blanda Figs10-12.Malewings:(10)Libellagolineata(Thailand,ChonBuri, andL. andamanensis(cf. BangPhra);—(II)L.balussp.n.(paratypefrom GreatNicobar);— Figs 10and 12).Fore- and (12)L andamanensis (SouthAndaman,Garacharma). 352 M. Hamalainen hindwings with 6-7 antenodals. Hindwing with 13-17postnodals; pterostigma black, covering 3-4 underlying cells. Abdomen (Fig. 3). — Even somewhatslimmer in appearance thaninL. blanda.Largely orange reddishaboveandonthesides.The black markings are much more reducedthaninL.blanda.SIblack on lower sides and anteriorly; Figs 13-15. Female 4th and 5'"abdominal segment, dorsal dorsally the black colour forms a view;(13) Libellagoblanda(Camorta); - (14)L. balus sp. rounded marking. In S2, the n.(paratypefromGreatNicobar); — (15)L. andamanensis narrow basal black ring and the (SouthAndaman,Beadonobad). subapical paired marking are connectedby a narrow middorsal dark stripe. S3-8 with obscure paired subapical markings, getting graduallysmallerinapicalsegments.Apex ofS8only verynarrowly black. S9-10whollyblack. Analappendages black, oftypical shape forthegenus. Measurements (inmm). - Hindwing18.5-21,abdomen(incl.appendages) 15.5-17. Male from Little Nicobar. — Thesingle availablematuremalediffers slightly fromthetopotypical malesby havingtheblackmiddorsalstripeonS2somewhat broaderatbaseandthepairedsubapical dorsalspotsonS3-8alittlemorepronounced. Headwithyellow markingson genae, baseofmandiblesandantennaepedicel, alsoa pairoftiny yellow spots posteriorofthetypicalsquaremarkings. FEMALE. — BothintheGreatandLittleNicobarfemalestheyellowishmarkingson thehead are quite similarto thoseof the single malefromLittleNicobar, i.e.more extensive than inmalesfrom GreatNicobar.Inthe agedfemalefromLittleNicobar, theshining blackanteriorsideofrhinariumhas turnedpruinosed gray.Colourpattern ofpro- and pterothorax quite similar as in male. Legs blackish. Wings hyaline. Pterostigmapresentinboth wings;grayishbrown,gettingpalerapicad,covering usually 4underlying cells. Foreandhindwings with 6-7antenodalsand 12-16postnodals. Abdomenblack, withthe lateraland dorsal yellow markings much broader and correspondingly the black dorsolateralbands on S2-7 much narrower than in L. andamanensis(cf. Figs 14-15). SI colouredas inmale.On S4-6theblackbands are wholly indentedsubapically by the yellow colour in the Little Nicobar specimen, apparently acharacterofagedspecimens. Thelateroventraledgeyellowishatthebasal halfofS5-8; intheLittleNicobarspecimen moreextensively yellow, narrowlyyellow alsoonS3-4.S8withayellowdorsalstripe, notquitereaching totheapex,very narrow shortlateralstripes in the middleof the segment. S9 black, with only small lateral yellow spots; in the Little Nicobar specimen also a dorsal spot present. S10 and appendages all black. Intersegmental rings between S8-9 (in some specimens also betweenS7-8) broadly palebrownish. Libellagoofthe Andaman andNicobarIslands 353 Measurements(inmm). —Hindwing19-21,abdomen13-14.5. distribution. — Thisspecies appearstobe confinedtoGreatNicobarandLittle Nicobar, thesouthernmostislandsofthearchipelago, which formthe ’’GreatNicobar” island group.The otherislands in this groupare so small, that presence of stream damselfliesthereis very unlikely. Records madeinAugust andDecember-February. CONSIDERATIONS ONTHESTATUS OFTHEN1COBARESE TAXA. - L. blanda has becomefinkedandlater synonymized withL. lineata, solely by misinterpretingthe original description, a goodreminderoftheimportanceofstudying thetypematerial. L.blandais easily separated from lineataby its denservenation.The shape ofmale abdomenis different. Inlineatathe abdomenis dorsoventrally more depressed, the broadestpoint atS4being broaderor as broadas thanthelength of S4(Fig.5). The abdomenofblanda maleisof differentslimmershape; S4being muchlonger than broad(Figs 1-2).Moreoverthecolourpattemofabdomenis completely different;the palemarkings inlineatabeing cadmiumorgolden yellow. Whereas inlineatamale (and alsoin indicamale), the wing base shows a clear yellowishtint, andthemain veins(especially R+Mandveinsaroundquadrangle)are muchpaleratwingbasethan apicad, inblandamalethewingbasesare hyaline andtheveinsuniformly dark. TheexistenceoftwodistincttaxaintheNicobarsisinteresting.Besidesthedifferences inthecolourpatternofthemaleabdomen,L.blandaandL.balussp. n. differclearlyin the shape of malerhinarium.In blanda(Fig. 6), theanterior flattenedfacet is more pronounced, its shining surfacebeing slightly concave and its lowerborderforming an obscureridge againstthe convex anteriorpart of therhinarium.In L bolus sp.n. (Fig.7) theshining facetislessdistinctlyflattened,itssurfacebeing somewhatconvex inthelowerhalf, withtheedge smoothly connectedtotheanteriorpartofrhinarium. In females,thefacetis smallerandmoresimilar. Among thechlorocyphids, itisnot easyto definewhatdifferencesare sufficientto rank apopulation belonging toadistinct speciesratherthanasubspecies. Inthis case thestructural differencein the shape of malerhinariumpoints more tothespecific difference,thanthemeredifferencesinthecolourpatternalone.Theviewisstrengthened by thediscovery that both inCamortaandGreatNicobar,the samestreams arealso inhabitedby undescribed Nosostictaspecies. Basedonthestrikingdifferencesinthe structure of male appendages and femaleprothorax, these superficially similar protoneurids belongtotwodistinctspecies, oneoccurring inCamortaandtheotherin GreatNicobar.Theislandgroupshaveremainedisolatedalsoduringallperiods ofsea lowering inthePleistoceneera.Thustheisolationhas lastedlongenough forcomplete speciation; nogene-flowhasbeenpossiblebetweenisolatedpopulationsofthesestrictly stationary streamdwellers. LIBELLAGOANDAMANENSIS (FRASER, 1924), STAT.REV. Figures4, 12,15 Micromerusandamanensis FRASER, 1924:410,fig.inpi. 24[orig.descr. of c?]; — FRASER, 1928:687-688,fig.inpi. 1[descr.of <?]. 354 M.Hamalainen Libellagoandamanensis: FRASER, 1934: 60-61, 66[key, fig.,descr.]. Libellagolineataandamanensis:CHHOTANIetal.1983:467,468,471-473,494[descr. ofthe first 5; downgradedasssp.; 8 3,4 5 listed from different localities in South Andaman,26-III/18-IV-1964,B.S.Lambaleg.]. Material. — (allPrashanth-Mohanraj&K.Veenakumari leg.,placedinauthor’s collection).— NorthAndaman; 2<J, Kalighat,20-X-1996;1 <3 ,Radhonagor, 19-X-1996. - SouthAndaman: 1 6, 1 2, Sipighat,dwarfcoconutblock,24-VII-1996; 1 <J, 1 2,Garacharma,C.A.R.I.Campus, 1-1-1998(2),28- 11-1998 (tj); 1 6, Bloomsdale,5-III-1998; 2 2,Chiriyatapa(mangrove forest), 11-III-I998,3 2, Beadonobad stream,29-1-1998 (1 2), 26-III-1998 (22). —LittleAndaman: 4<J,22,HutBay,8/12-XI- 1998, male. — Head. — Labium largely black, pale atbase. Rhinarium(ante- and postclypeus) withanteriorsideshining black, withbrownishbordersandwithadistinct shining flattenedfacet; posterior part mattblack. Rest ofthe head mattblack, with threepairsofsmallyellowishroundedmarkings asfollows: betweentheantennae,on sideofthelateralocelliandaspostocularspots.Moreover,theoccipital marginnarrowly yellow inthe middle, in mostspecimens protruding with a roundor triangle shaped extensioninthemiddle. Prothorax blackwith yellowmarkings: alinearmarking onanteriorlobe,apair ofpearl-shaped markings on sides of medianlobe and a pair ofround spots on ventrolateraledge of medianlobe.Asmall marking midlineintheposterior lobe,of variable(often bell, triangle ordroplet)shape. Pterothorax jetblack, withyellowish stripes, quitesimilarly patterned toL. blandaandL.balussp. n.(cf.Fig. 9).Dorsalcarinafinelyyellow. Inteneralspecimens theventral sidefurnishedwithtwo pairsof yellow markings,in olderspecimens the ventralsideblack.Legsblack, inner(flexor)sideofalltibiaepulverulantwhite.Middle partoftheinnersideofanteriorfemoraalsowhitish. Wings (Fig. 12). — Hyaline,withafaintyellowish tintatbase, somewhatclearer atcostalarea.Tipofforewing withlargeblackspot(somewhat variableinsize),reflecting metallicblue.Theutmosttipsofhindwingslightly enfumed.Pterostigmapresentonly inthehindwing, black,covering 3-4underlying cells.VenationdenserthaninL. lineata. Usually 6(seldom5 or7)antenodalsinbothwingsand 12-14postnodals inhindwing. Abdomen(Fig.4). — Similarlyshaped toL.blanda.Largely brownishyellowon sides, with broad continuous, black dorsal stripe, regularly broadening around intersegmentalrings.PosteriorhalfofS8and S9-10allblack. Analappendages black, ofthetypical shapeforthegenus. Measurements (inmm). — Hindwing19-21,abdomen(inc.appendages)14.5-16. FEMALE. — Headwithmore yellowmarkings thaninmale.Besidesthethreepairs ofspots as inmale, therearebroadobliquebands onfrons. Genae,baseof antennae andeye marginalso yellow. Borders ofanteriorsurfaceofrhinariumyellowish and bases of mandiblesyellow. Younger females havealsolabiumlargely yellow (only tips black) andapairof yellow dots(sometimes fused)inlabrum.Colourpatternof pro-and pterothorax resemblesthat inmale.Legs blackish, slightly pale pruinosed.