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Bull. not. Hist. Mas. bond. (Zool.) 68(2): 57-74 



Issued 28 November 2002 



Review of the Dispholidini, with the 

 description of a new genus and species from 

 Tanzania (Serpentes, Colubridae) 



D.G. BROADLEY 



Research Associate, Natural History Museum of Zimbabwe, Bulawayo, Zimbabwe 



Present address: Biodiversity Foundation for Africa, P.O. Box FM 730 Famona, Bulawayo, Zimbabwe, email: 



broadley @ telconet. co.zw 



V. WALLACH 



Museum of Comparative Zoology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, U.S.A. email: 

 vwallach@oeb. harvard, edu 



SYNOPSIS. The tribe Dispholidini (Bourgeois 1968) is reviewed, paying particular attention to dentition and visceral anatomy. 

 A new genus and species, Xyelodontophis uluguruensis, is described from the Uluguru Mountains in Tanzania. All five genera 

 have enlarged rear maxillary teeth. Thrasops seems to be basal, Rhamnophis shows the development of dagger-like teeth tapering 

 from base to tip. then the other three genera appear to radiate, with Xyelodontophis having more derived dagger teeth broadest 

 in the middle, while Dispholidus and Thelotornis seem to have independently developed enlarged grooved rear fangs. 



Thrasops schmidti is recognised as a relict evolutionary species. No subspecies of Rhamnophis aethiopissa or Dispholidus 

 typus are recognised, but the population of Dispholidus on Pemba Island probably represents an undescribed species. 



INTRODUCTION 



MATERIALS AND METHODS 



From the time of Boulenger's catalogues ( 1 893-96), it was custom- 

 ary to separate the aglyphous colubrid snakes (subfamily Colubrinae) 

 from the opisthoglyphs (subfamily Dipsadomorphinae or Boiginae). 

 see for example Loveridge (1957) and FitzSimons (1962). 



Bourgeois (1968) erected a subfamily Dispholidinae, including 

 the aglyphous genera Thrasops Hallowell 1857 and Rhamnophis 

 Giinther 1862, and the opisthoglyphous genera Dispholidus 

 Duvernoy 1 832 and Thelotornis A. Smith 1 849. Subsequent authors 

 have often treated Rhamnophis as a synonym of Thrasops (e.g. 

 Hughes & Barry, 1969; Pitman, 1974; Spawls, 1978; Hughes, 1983; 

 Trape & Roux-Esteve, 1995; Chippaux, 1999) and many have 

 considered these aglyphous snakes to be members of the tribe 

 Philothamnini (e.g. Dowling & Duellman, 1978). 



During a review of the genus Thelotornis in East Africa (Broadley, 

 2001), a snake from montane forest on the summit of the Uluguru 

 Mountains was initially assumed to represent a new species. How- 

 ever, examination of its rear maxillary teeth showed that they were not 

 the anticipated grooved fangs, but distinctive curved dagger-shaped 

 teeth with sharp anterior and posterior ridges, which are widest 

 midway along the tooth. To determine the relationships of this strange 

 snake to the other taxa of the Dispholidini, its skull was prepared (after 

 examination of the dental gland) and compared with skulls of the other 

 genera. This prompted a review of the genera Thrasops and 

 Rhamnophis, which appear to represent basal taxa of the Dispholidini. 

 As the 'Dagger-tooth Vine Snake' of the Uluguru Mountains seems to 

 be transitional between Rhamnophis and Thelotornis, but cannot be 

 accommodated in any of the existing genera of the tribe Dispholidini, 

 it is proposed to erect a new genus and species for it. In external 

 appearance and scale counts it resembles Thelotornis, but it lacks the 

 distinctive horizontal key-hole shaped pupil of that genus. 



It is with pleasure that we dedicate this paper to Garth Underwood, 

 in recognition of the major contributions that he has made to our 

 understanding of African snakes. 



This study is largely based on material available in the Natural 

 History Museum of Zimbabwe and the Museum of Comparative 

 Zoology, Harvard, with additional data derived from the literature. 

 Unfortunately the collections in the Natural History Museum were 

 not accessible. Loveridge's 1944 revisions of Thrasops, Rhamnophis 

 and Thelotornis were based largely on scalation, supplemented by 

 maxillary tooth counts and coloration of head and neck in the case of 

 Thelotornis. We have emphasised the morphology of the rear max- 

 illary teeth and skull, and have also used data from the visceral 

 anatomy, using the Philothamnini as the outgroup for comparative 

 purposes. Data for good series of Philothamnus angolensis, 

 Hapsidophrys lineatus and H. smaragdina were available [Broadley 

 (1966) provisionally synonymised Gastropyxis Cope 1860 with 

 Hapsidophrys Fischer 1856, and this move is supported by the 

 visceral data]. In the species accounts we have only presented 

 chresonymies, full synonymies are included in the review of the East 

 African Thelotornis (Broadley, 2001) and investigation of the vari- 

 ation in the wide-ranging genus Dispholidus awaits future workers! 



In the description of the visceral anatomy, the mean value for most 

 characters as % snout-vent length (SVL) is presented first, followed 

 parenthetically by the range or midpoint (MP) value. When only the 

 name of an organ is given, the value represents its length. Ratios of 

 two visceral characters are presented in fractional notation. When 

 only one value is given for a character, it is identical in the two 

 specimens or differs by less than 0.1%. 



The position of the umbilicus is determined by the most anterior 

 ventral bearing a scar (the scar usually covers three ventrals and the 

 umbilicus exited through the medial scute). The umbilical scar-vent 

 interval is calculated by dividing the number of ventrals from the 

 scar to the vent by the total number of ventral scutes. 



Material for which skulls or viscera were examined is listed in 

 appendices. Institutional abbreviations follow Leviton etal. (1985), 

 with the addition of: 



© The Natural History Museum, 2002 



