TRIMERESURUS HAGENI AND T. SUMATRANUS 



109 



Table 2 Characters used for multivariate analysis of T. sumatranus & T. hageni. 



Characters 



Males 



Females 



1 . No. of ventral scales 



2. No. of subcaudal scales 



3. %VS position of reduction from 21 to 19 body scale rows 



4. %VS position of reduction from 19 to 17 body scale rows 



5. %DV position of reduction from 19 to 17 body scale rows 



6. %VS position of reduction from 1 7 to 15 body scale rows 



7. %CS position of reduction from 14 to 12 tail scale rows 



8. %DV position of reduction from 14 to 12 tail scale rows 



9. %CS position of reduction from 10 to 8 tail scale rows 



10. % DV position of reduction from 10 to 8 tail scale rows 



1 1 . %CS position of reduction from 8 to 6 tail scale rows 



12. %CS position of reduction from 6 to 4 tail scale rows 



13. No. of supralabial scales 



14. No. of sublabial scales 



15. No. of scales bordering the supraocular scales 



1 6. Minimum no. of scales separating the supraocular scales 



1 7. Maximum no. of scales separating the supraocular scales 



1 8. No. of internasal scales 



19. No. of scales separating the fourth supralabial scale form the subocular scale 



20. No. of scales separating the fifth supralabial scale form the subocular scale 



21 . No. of scales contacting the suboculars. excluding the preoculars and postoculars 



22. Average no. of scales between the first ventral scales and the anterior genial scales 



23. No. of scales between the last sublabial scales and first vental scales 



24. Presence of stripe on dorsal scale row one 



25. No. of scale rows involved in stripe 



26. Presence of postocular stripe 



27. No. of scale rows involved in postocular stripe 



28. Presence of dark edging on body scales 



29. No. of bands on body 



30. Mean no. of scales of three half bands on body 



3 1 . Mean no. of scales between three half bands on body 



32. Presence of dark edging on head scales 



* indicates significance value p=<0.05 (ANOVA) 



division in both sexes. This corresponds to T. sumatranus in Borneo, 

 central Sumatra and southern Thailand and T. hageni in southern 

 Thailand, West Malaysia, Singapore, north Sumatra, south Sumatra. 

 Nias and Siberut. The species are best distinguished by head scalation. 

 but can also be identified by colour and pattern. 



Geographic variation is also present at the intra-specific level. 

 The Siberut and Nias specimens show stronger differentiation in 

 males than in females. Their phenotypic similarity to mainland T. 

 hageni is based mainly on scalation characters. Moreover, on the 

 basis of colour and pattern, the Nias population is quite distinct with 

 head and body scales strongly edged in black. Nias was last con- 

 nected to Sumatra in the geologically recent past (c. 18.000 years 

 ago), whereas Siberut has been isolated for around one million years 

 (Dring et ah, 1989). The extent to which these populations have 

 diverged from the mainland population will be investigated using 

 molecular methods and may lead to taxonomic revisions. 



Sumatran populations are represented by few specimens, but 

 these exhibit the same general pattern in males and females: T. 

 sumatranus from central Sumatra appear to be strongly differenti- 

 ated from the Borneo OTU, whereas T. hageni from north and south 

 Sumatra are only weakly differentiated from the mainland OTU. 

 This pattern will be tested when additional data becomes available. 

 An analysis of the phylogenetic relationships of these populations, 

 using mitochondrial sequence data, is also underway and should 

 help to clarify their status. 



Acknowledgements. We thank our collaborators at the University of 

 Science, Malaysia, and in particular Dr. Shahrul Anuar. We also thank the 

 staff and curators of the following institutions for allowing us access to their 



specimens: BMNH. FMNH. IMR. KNP, MCZ, MHNG, NMBA, NMW. PH. 

 QSM1.ZRC. This study was supported by the Natural Environment Research 

 Council studentship to KLS (NER/S/A2O0O/03695), the Leverhulme Trust 

 (F/I74/I and F/ 174/0). the Wellcome Trust (057257/Z/99/Z and 060384/Z/ 

 00/Z), and the Darwin Initiative (162/6/65) with additional support for 

 fieldwork from the Linnaean Society of London. Side. Bonhote, Omer- 

 Cooper and Westwood Fund. 



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