A contribution to the systematics of two commonly confused pitvipers from the Sunda region: Trimeresurus hageni and T. sumatranus

5 Pages·2002·2.8 MB·

by  K L Sanders

XX (ZS70&x,^
Bull. nut. Hist. Mus. Lond, (Zool.)68(2): 107-11 Issued28November2002
A
contribution to the systematics of two
commonly confused pitvipers from the Sunda
Region: Trimeresurus hageni and
T.
sumatranus
K. L. SANDERS, A. MALHOTRA AND R. S. THORPE
SchoolofBiologicalSciences, UniversityofWales, Bangor, GwyneddLL572UW, Wales, UK.
SYNOPSIS. ThesystematicsoftwoSoutheastAsiangreenpitviperspecies,TrimeresurushageniandT.sumatranus,areinvesti-
gatedbycanonicalvariateanalysis.PreliminaryresultsrevealtwomorphologicalformscorrespondingtomainlyT.hageniinWest
Malaysia,ThailandandSingaporeandT.sumatranusinBorneo.AllopatricpopulationsofbothtaxaareexaminedfromSumatra.
Geographicvariationispresentinbothspecies,whicharedistinguishedmainlybyheadscalation.butalsobycolourandpattern.
INTRODUCTION relating to scalation, colour and pattern were recorded for each
specimen. Ventral scales were counted from head to vent, with the
Trimeresurus sumatranus (Raffles, 1822) and T. hageni (Lidth de first ventral identifiedaccording tothe methodofDowling (1951).
The positions of scale reductions along the body (recorded as the
Jeude, 1886) are closely related species, occupying low elevations
in undisturbed forests and having largely overlapping ranges. The number of the ventral or subcaudal scale opposite which it was
situated) were transformed to percentage ventral scale (%VS) or
systematicsofthese speciesandtheirprecisedistribution isanarea
oflong-standingconfusion. ManyworkersassignbothspeciestoT. caudalscale(%CS)position, inordertocompensateforvariationin
ventral and subcaudal scale number. Male and female specimens
sumatranusbydefault(Tweedie, 1983;Lim, 1991;Jintakune, 1995;
David and Vogel, 1996) and the status of T. hageni has been in weretreatedseparatelyinallanalysestoavoidbiascausedbysexual
dimorphism.
dispute since its initial description (Lidth de Jeude, 1886; Lidth de
Specimensweregroupedby locality intooperational taxonomic
Jeude, 1890;Boulenger, 1896; Brongersma, 1933).
units (OTUs). Two groups dominated the analysis, one was com-
T.hageniwasdescribedasaseparatespeciesfromT.sumatranuson
prisedofspecimensfromThailand. West MalaysiaandSingapore,
thebasisthatonlyoneortwosupralabialscalesareincontactwiththe
andanotherwascomprisedofspecimens from Borneo(Sabah and
subocular(comparedwiththreeinT.sumatranus),andthedarkedges
onheadandbodyscalesanddorsalcross-bandsthatarecharacteristic Sarawak). Thesegroupswereshown tobe monophyleticby mole-
cular analysis (unpublished data), which revealed a clear
ofT.sumatranusarenotpresent(LidthdeJeude, 1886).Thespecies' distinction between western specimens that lacked dorsal cross-
distribution is widely debated, but specimens from south Thailand,
WestMalaysiaandSingaporearenormallyassignedtoT.hageni,and bandsand hadat mosttwosupralabialsconnectedtothe subocular
specimens from Borneo are normally assigned to T. sumatranus scale, and eastern specimens that had dorsal cross-bands and had
(DavidandVogel, 1996;Coxetal., 1998;StuebingandInger, 1999), three supralabials in contact with the subocular scale. Molecular
butseeDring(1979)whoplacedspecimensintheNHMcollections data was not available for specimens from Sumatra, and these
(fBBrorotomhnWsgpeeesrctsimMeasa,laary1es9t3ih3ao;,usgDohrutitnthgoeroenctcaTuihr,aio1ln9a8Sn9ud;maaCntdorxSaaearlnaadiw.sa,ukr1ir9n9oT8u.)ns.duimnagtirsalnaunsd.s iwnerEoeanceghrOoOTuUTp.eUdwiandsivcihdeucaklleydtporiaovroitodfcuormtbheirnianngalyssyimspautsriincgsPpreicniceis-
There have been few attempts to resolve the systematics of T. pal Component Analysis, which does not require that individuals
hageniand T. sumatranussincetheirinitial description; these have bOeTUasssiwgansedcognrfoiurpmsedprwiiotrhtothetheexcaenpaltyisoins.ofThoeneisntpeegcriitmyenoffrtohme
been based on small sample sizes and a traditional character-by-
character approach (Boulenger, 1896; Brongersma, 1933). Given Betong (southThailand), which haddark banding and in the PCA
ordination wasclosesttothe BorneoOTU. In subsequent analysis
the levels ofgeographic, ontogenetic and sexual variation usually
this specimen was grouped separately from the other western
p1r9e9s7e)n,tthinevsiypsetremsapteiccisesof(tWhieissetetraxeataisl.b,es1t99a2p;prMoaalchhoetdrausainndgTmhoodrepren, specimens. The OTUs used and their sample size for each sex is
statistical methods based on a broad range of morphological listed in Table 1.
characters. In this paper, we present preliminary results from an Variation between OTUs was tested forindividual charactersby
meansofone-wayanalysisofvariance (ANOVA). Onlycharacters
ongoinginvestigationofthesystematicsandinterrelationshipsofT.
hageniand T. sumatranus. showing significant between-OTU variation were used in subse-
quent analyses. These are presentedinTable 2.
Canonicalvariateanalysis(CVA)wasusedtoinvestigatepatterns
ofgeographicvariationbetweenOTUs.Thismethodmaximisesthe
MATERIALS AND METHODS
separationbetweengroupsrelativetovariationwithingroups.Itisa
standard multivariate method and has been applied successfully to
Weexamined78specimensfrommuseumcollectionsintheUnited numerousmodelsofgeographicvariationinreptiles (Wiisteretal.,
States, Europe and Malaysia (Figure 1). A total of 93 characters 1992; Thorpeetal., 1994; Daltry etai, 1996).
©TheNaturalHistoryMuseum.2002
108 K.L. SANDERS ETAL.
Fig. 1 Geographicoriginofspecimensusedinmultivariateanalysis.S=Trimeresurussumatranus;H=Trimeresurushageni;U=unidentified
specimens. ShadingrepresentstheknowndistributionofT. hageniand/orT.sumatranus.
Table1 ListofOTUsandsamplesizeforeachsex. West Malaysia and Singapore and those normally assigned to T.
sumatranus from East Malaysia. The Siberut OTU and the single
OTU SampleSize
specimensfromNiasandnorthernSumatraareclosesttothemain-
Males Females
land T. hageni population. The specimens from Betong, Thailand
Thailand,WestMalaysia,Singapore 6 15 and central Sumatra are closest to the Borneo OTU, but are well
NorthSumatra 1 (Medan) 1 1 differentiated onCV2.
NorthSumatra2(Medan) 1 Analysisoffemalesalsoshowsstrongdifferentiationbetweenthe
CCSeeonnutttrrhaallSuSSmuuammtaarttarraa121(P((aPPlaaeddmaabnnaggn))g) 1 111 TThhaeilSainbde,rWutesatnMdalNaiyassiaspaencdiSmienngsapaorreepOhTenUotaynpdictahlelByocrlnoesoeOtToUT..
Nias 1 10 hageni from Thailand, West Malaysia and Singapore. Specimens
Siberut 3 3 from north and south Sumatra are also closely affiliated to this
EastMalaysia 4 18 mainland population. The specimens from central Sumatra are
Betong(southThailand) 1 closest to the Borneo population along CV1, although are clearly
Total 7 51
differentiatedon CV2.
CVAanalysiscanbe usedto identify thecharacters thataccount
Museum Acronyms
formostvariationbetweengroups.Inbothsexesscalationcharacters
BMNH The Natural History Museum, London, formerlythe were more important in distinguishing between thetaxathan were
BritishMuseum (Natural History), London charactersrelatingtocolourandpattern.Themostimportantcharacter
FMNH FieldMuseumofNatural History, Chicago is the fifth supralabial scale, which meets the subocularscale in T.
IMR InstituteofMedical Research, KualaLumpur sumatranusandin T. hageniisseparatedfromthesubocularbyone
KSP Sabah ParkZoological Museum, MountKinabalu scale. Alsoimportantisthefrequentpresenceofaninternasal scale
National Park, Sabah inT.sumatranus,whichisusuallylackinginT. hageni. Inaddition,
MCZ MuseumofComparativeZoology, Harvard T.sumatranushasfewersupralabialscalesandfewerscalesbetween
MHNG Museumd'HistoireNaturelle deGeneva, Switzerland supraoculars than T. hageni. Ourwork verifies two ofthe original
NMBA Naturhistorisches Museum Basel, Switzerland diagnosticcharactersusedbyLidthdeJeude(1886)whodescribed
NMW Naturhistorisches Museum Vienna, Austria T. hageniasadistinctspeciesthatlacksdorsalcross-bandsandhas
QSMI Queen SaovabhaMemorial Institute, Bangkok fewer supralabial scales in contact with the subocularscale. How-
PH Perhelitan, KualaLumpur ever, we did not finddark edging on head and body scales to be a
ZRC Raffles MuseumofBiodiversity Research, National validdiagnosticcharacteronthebasisthatT.hagenispecimensfrom
UniversityofSingapore, Singapore Nias have very strong dark edges on their head and body scales.
RESULTS
DISCUSSION
TheCVAofmales showsclearseparationalongthefirstcanonical
variateofspecimensnormallyassignedtoT. hagenifromThailand, The results ofthis preliminary analysisreveal amajorphenotypic
....
TRIMERESURUSHAGENIAND T. SUMATRANUS 109
Table2 CharactersusedformultivariateanalysisofT. sumatranus& T. hageni.
Characters Males Females
1 No.ofventral scales
2. No.ofsubcaudalscales
3. %VSpositionofreductionfrom21 to 19bodyscalerows
4. %VSpositionofreductionfrom 19to 17bodyscalerows
5. %DVpositionofreductionfrom 19to 17bodyscalerows
6. %VSpositionofreductionfrom 17to 15bodyscalerows
7. %CSpositionofreductionfrom 14to 12tail scalerows
8. %DVpositionofreductionfrom 14to 12tail scalerows
9. %CSpositionofreduction from 10to8tailscalerows
10. %DVpositionofreductionfrom 10to8tailscalerows
11 %CSpositionofreduction from8to6tailscalerows
12. %CSpositionofreduction from6to4tailscalerows
13. No.ofsupralabialscales
14. No.ofsublabial scales
15. No.ofscalesborderingthesupraocularscales
16. Minimumno.ofscalesseparatingthesupraocularscales
17. Maximumno.ofscalesseparatingthesupraocularscales
18. No.ofinternasal scales
19. No.ofscalesseparatingthe fourthsupralabial scaleformthesubocularscale
20. No.ofscalesseparatingthefifthsupralabial scaleformthesubocularscale
21 No.ofscalescontactingthesuboculars.excludingthepreocularsandpostoculars
22. Averageno.ofscalesbetweenthe firstventral scalesandtheanteriorgenial scales
23. No.ofscalesbetweenthe lastsublabial scalesand first vental scales
24. Presenceofstripeondorsalscalerowone
25. No.ofscalerowsinvolvedinstripe
26. Presenceofpostocularstripe
27. No.ofscalerowsinvolved inpostocularstripe
28. Presenceofdarkedgingonbodyscales
29. No.ofbandsonbody
30. Meanno.ofscalesofthreehalfbandsonbody
31 Meanno.ofscalesbetweenthreehalfbandsonbody
32. Presenceofdarkedgingonheadscales
* indicatessignificancevaluep=<0.05(ANOVA)
divisioninbothsexes.ThiscorrespondstoT.sumatranusinBorneo, specimens: BMNH.FMNH.IMR.KNP,MCZ,MHNG,NMBA,NMW.PH.
central Sumatra and southern Thailand and T. hageni in southern QSM1.ZRC.ThisstudywassupportedbytheNaturalEnvironmentResearch
Thailand,WestMalaysia,Singapore,northSumatra,southSumatra. Council studentshipto KLS (NER/S/A2O0O/03695), the LeverhulmeTrust
NiasandSiberut.Thespeciesarebestdistinguishedbyheadscalation. (F/I74/I and F/174/0).theWellcomeTrust (057257/Z/99/Zand060384/Z/
butcan alsobe identified bycolourand pattern. 00/Z), and the Darwin Initiative (162/6/65) with additional support for
Geographic variation is also present at the intra-specific level. fieldwork from the Linnaean Society of London. Side. Bonhote, Omer-
The Siberut and Nias specimens show stronger differentiation in CooperandWestwoodFund.
males than in females. Their phenotypic similarity to mainland T.
hageni is based mainly on scalation characters. Moreover, on the
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110 K.L. SANDERS ETAL.
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Fig.2 CanonicalVariateAnalysisofT. hageniandT. sumatranuspopulations(top=males;bottom=females).
TRIMERESURUSHAGEN1AND T. SUMATRANUS 111
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47:97-113. NMW28158.1 Kedah,W. Malaysia F
NMW
28 58.2 Kedah.W. Malaysia F
BMNH 19136.9.12.3 Betong.Thailand M
Appendix 1 Specimens used in morphological BMNH 1884.1.8.47 Nias, Indonesia F
analysis BMNH 1884.1.8.46 Nias. Indonesia F
BMNH 1884.12.31.13 Nias. Indonesia F
BMNH 1884.12.31.14 Nias. Indonesia F
MUSEUM/FIELDREF LOCALITY SEX BMNH 1977.1237 Siberut, Indonesia M
QQMMMMSSCHHHMMZNNNIIGGG11322112001477790922039...898579 SSSPKKuuriaurrannaaabggltliana,paTTLo,ThhruaahTemnnahiiipa,,luiarTTln,hhadaanWiid.llaaMnnaddlaysia MMMMMF BBBBBBMMMMMMNNNNNNHHHHHH 111111899999837767069978......992212..66821187792090..57 GGSSSKiii..ubbnMaBeegulerralauunpttuoT,,o,merIIk.eSnnuaddW,roo.annWeew.MssaaiiMklaaaalyasyisaia MMMFFF
KSP04361 KotaMardu,Sabah F
PH KrauWR,W. Malaysia F
PPPHHHno.79 TKSaeulpaaaln,agWoJr.a,siMWna,.lWaMy.asliMaaaylsaiyasia FFF IIK1MMSMRRPR01114000343462622747190 SUBBiuulkkmuiipttGaonTLmgaa,bkwaaaWiku..,.WMSW.aa.lbMaMaayahlslaiayayssiiaa FFFF
FFFFPFFFFFFHMMMMMMMMMMNNNNNNNNNNnoHHHHHHHHHH.122111111113333448843349988833388996877968645828848397899788900 JSUUKKKMKKKeaaaaaalloelpppppnuutnaiiiiidadntttttGGaogMooloDDDDDBammiiiiiroarsssss,bbnitttttdkaagrrrrrWu,iiiii.kk.,ccccc,,tttttWS,,,,,MS.aWWaaSSSSSb..MlbaaaaaaaaarrrrrhMMlyhaaaaaaaaswwwwwllyiaaaaaaasakkkkkyyissaiiaa MMFFFFFFFFF ZZZAIIKKKKFLLLMMRRRLSSSSSRRCCC090009222I811105...01119022925152999989699333588764 SEPSSSSPPUiiieoooinlbbbrrrnmudeeeaiigparrrnnkGkauuuugg,hotttn,,l,.,WmgRaSS..boIII,aaannnmWMbbTdddkp.aaahooo.ilhhnnnanMaeeeiWaysssl.NlsiiiaPaaaainM,yadasWlia.ayMsailaaysia MMMMMMFFFF
FMNH243943 Mendolong.Sabah F AFS97b20 Satun,Thailand F
FMNH230064 DanumValley.Sabah F AFS0005 KualaLumpur.W.Malaysia F
FMNH230063 DanumValley,Sabah F AFS/KLSindicatewildcaughtspecimensexaminedunderanaesthesia.