HEMIPENIAL VARIATION IN CROTAPHOPELT1S 



55 



In the northern part of its distribution (The Usambara Mountains) 

 the hemipenes of Crotaphopeltis tornieri usually have two slightly 

 enlarged spines, one on the outside of the truncus and one (rarely 

 missing) on the asulcate side. Based on external morphology, 

 Rasmussen (1993) found significant differences between the popul- 

 ations of C. tornieri from East and West Usambara Mountains. The 

 present results of the genital investigation do not lend support to the 

 recognition of different forms, nor do molecular (Gravlund. 2002) or 

 microdermatoglyphic (Berggreen, 1996) studies. Accordingly, the 

 differences found in numbers of ventral and caudal scutes between 

 these areas are probably due to genetic drift in small, isolated 

 populations. 



Gravlund (2002) found significant differences between the mole- 

 cular composition of the northern and southern populations of C. 

 tornieri in the Eastern Arc. In particular, the population from the 

 Rungwe Mountains is very different molecularly from those of the 

 Udzungwa and the Usambara Mountains. The present study also 

 shows slight hemipenial differences between these populations. In 

 the hemipenes of the populations from Kihanga River (Udzungwa 

 Scarp Forest Reserve) and the Rungwe Mountains only the enlarged 

 spine on the outside of the truncus is visible. The picture, however, 

 becomes blurred as hemipenes of specimens from Kilanzi-Kitungulu 

 (Udzungwa Mountains) may have either a relatively small spine on 

 the outside and likewise on the asulcate side or various enlarged 

 spines on the truncus. Thus, the data on genital morphology indicate 

 that the spine ornamentation of the lower truncus in the hemipenes 

 of C. tornieri is variable even within single populations and with 

 current knowledge should not be used for defining different taxa 

 within the C. tornieri complex. This is in accordance with Berggreen 

 (1996) who found some microdermatoglyphic variation within and 

 between the various populations. The variation, however, was not 

 population specific. Crotaphopeltis tornieri (s.l.) is restricted to the 

 montane forest of the Eastern Arc of Tanzania and is easily distin- 

 guished from sympatric/parapatric C. hotamboeia from the lowland 

 savanna. 



Thus, irrespective of the fact that intraspecific variation may 

 occur within the various species of Crotaphopeltis, the ornamenta- 

 tion of the lower truncus serves at least to distinguish between the 

 males of sympatric or parapatric species. The length at least of the 

 inverted hemipenes may also serve to distinguish between the 

 species and so may the unique rows of accessory spines in the 

 hemipenes of C hippocrepis. Here, it is interesting to note, that the 



pattern of the latter species is similar (Dowling, in litt.) to that of the 

 sister-genus Dipsadoboa (Rasmussen, 1979), which is also charac- 

 terized by similar, highly derived genital morphological features 

 (Rasmussen, 1993b). 



ACKNOWLEDGEMENTS. For the loan and making available material for 

 examination we thank C. McCarthy (BMNH), R. Drewes (CAS), J. Rosado 

 (MCZ), D. Meirte (MRAC), M. Hoogmoed (RMNH). L. Ford (USNM), and 

 W. Bohme (ZFMK). We are grateful to B.T. Clarke and two anonymous 

 referees for commenting on the manuscript. Support for travel for the junior 

 author to Tervuren, Bonn, and London has been gratefully received from the 

 Danish National Research Council, Grant no. 56043. 



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