ISSN 0067-9208 NATURAL SCIENCES VOLUME 29, PART 2 NOVEMBER 2013 First records of the egg-eating snake Dasypeltis confusa Trape & Mané, 2006 in Nigeria and Chad, with range extensions for Ghana by Michael F. Bates Department of Herpetology, National Museum, P.O. Box 266, Bloemfontein 9300, South Africa E-mail: [email protected] ABSTRACT Bates, M.F. 2013. First records of the egg-eating snake Dasypeltis confusa Trape & Mané, 2006 in Nigeria and Chad, with range extensions for Ghana. Navors. nas. Mus., Bloemfontein 29(2): 17-27. New records are provided for the egg-eating snake Dasypeltis confusa from three West African countries. These include the first records of this species for Nigeria, based on specimens from four localities (Jos and Zonkwa areas) in the centre of the country; and the first record for Chad, based on a specimen from Mayo-Kebbi in the south-west of the country. In addition, the known range in Ghana is extended to Yabraso in the central part of the country and the town of Wa in the north-west. The absence of records in several areas of apparently suitable savanna habitat in west and central Africa suggest that this species may have a much more extensive range than currently known. (Dasypeltis confusa, distribution, West Africa, Nigeria, Chad, Ghana) ISBN 978-1-86847-154-6 18 Navors. nas. Mus., Bloemfontein, Volume 29, Part 2 CONTENTS INTRODUCTION ................................................................................................................ 18 MATERIALS AND METHODS ......................................................................................... 20 RESULTS AND DISCUSSION ........................................................................................... 20 Scalation ......................................................................................................................... 20 Colour pattern ................................................................................................................. 21 Geographical distribution ............................................................................................... 23 ACKNOWLEDGEMENTS ................................................................................................. 25 REFERENCES ..................................................................................................................... 25 INTRODUCTION Trape & Mané (2006a) described three new species of Dasypeltis Wagler, 1830 from West Africa, including Dasypeltis confusa. Trape et al. (2012) subsequently confirmed the status of these species based on a molecular analysis of West African Dasypeltis. These authors also described Dasypeltis parascabra, raised Dasypeltis gansi latericia Trape & Mané, 2006 to full species status, and confirmed that Dasypeltis scabra (Linnaeus, 1758) does not occur in West Africa. There are now 12 recognized species of egg-eating snakes (genus Dasypeltis) in Africa and the Arabian Peninsula (Gans 1959, 1964; Trape et al. 2012). Dasypeltis confusa occurs mainly in savanna areas of sub-Saharan Africa south of 14oN latitude. It appears to be largely restricted to the Guinea Savanna, from southern Senegal to Guinea, southern Mali, southern Ivory Coast, Ghana, Togo and Benin, southwards to Cameroon, Gabon, Republic of the Congo, Angola, western Zambia and parts of Democratic Republic of the Congo, then eastwards through Central African Republic to Southern Sudan and Uganda (Gans 1959, 1964―‘D. scabra’ with ‘5L’ dorsal colour pattern; Chirio & LeBreton 2007; Pauwels & Vande werghe 2008; Bates & Broadley 2008a,b; Trape & Mané 2006a,b; Segniagbeto et al. 2011; Trape et al. 2012; Bates et al. 2012; Broadley & Bates in prep.). In Cameroon it has also been recorded from savanna- forest mosaic (Chirio & LeBreton 2007), and it occurs in both savanna and coastal grasslands in Gabon (Pauwels & Vande werghe 2008). However, many areas within its general range are poorly surveyed and lack any records (see Trape et al. 2012). Dasypeltis confusa is characterised by its ‘5L’ dorsal colour pattern (see Gans 1959) which consists of large dark saddles, oval to more-or-less diamond-shaped, joined for the most part to the dark lateral bars on either side of the body, on a grey to pale brown back (Fig. 1; Trape & Mané 2006a,b). The dark markings often have a distinct white margin that tends to emphasise the linked pattern (e.g. pl. 8, fig 6 in Gans 1959; p. 403 in Chirio & LeBreton 2007; fig. 205 in Pauwels & Vande weghe 2008). Also helpful for distinguishing D. confusa from other species of Dasypeltis―at least in West Africa―is the combination of 23-26 midbody scale rows; ventrals 213-227 (males), 224-242 (females); and subcaudals 65-73 (males), 53-67 (females) (Trape & Mané 2006a; repeated by Trape et al. 2012). 2013 M.F. Bates – New records of Dasypeltis confusa in West Africa 19 Figure 1: Dorsal view of the holotype (MNHN 2006.0303, adult female; Ibel, south-eastern Senegal) of Dasypeltis confusa at the Muséum national d’Histoire naturelle, Paris. The specimen was photographed while submerged in ethanol. (Photo: M.F. Bates) Most of Gans’ (1959) Nigerian Dasypeltis are referable to the forest species Dasypeltis fasciata A. Smith, 1849 (but see discussion below). Although he did not record any Dasypeltis with a ‘5L’ dorsal colour pattern (= D. confusa) from this country, Gans did report a ‘5N’ D. scabra from Lagos which Trape et al. (2012) later referred to their new species, Dasypeltis parascabra. However, Gans (1959) did record ‘D. scabra’ with ‘5L’ dorsal pattern (= D. confusa) from the Batouri area (East Province) in adjacent Cameroon. In a table (appendix B) showing the occurrence of snake species in savanna regions of Africa, Hughes (1983) recorded D. scabra from Nigeria (no specific localities given), while Chirio & LeBreton (2007) list Nigeria in the range of D. confusa without providing detailed localities. This species has not previously been recorded from Chad (see Gans 1959, 1964; Trape & Mane 2006a,b; Trape et al. 2012). Although D. confusa has been recorded from south-eastern Ghana (as ‘5L D. scabra’, Gans 1959; see also Trape et al. 2012), there are no records of this species in the central and north-western parts of the country. During September 2011 the author visited the Natural History Museum in London and the Muséum national d’Histoire naturelle in Paris to examine specimens of Dasypeltis as part of a revision of the taxonomy and distribution of the genus. The opportunity was taken to examine in detail the holotype of D. confusa in Paris (MNHN 2006.0303) and several specimens with the ‘5L’ dorsal colour pattern (see Gans 1959), including a few specimens from West Africa (Nigeria, Chad and Ghana). Specimens examined included the first records of D. confusa from Nigeria and Chad, and the first records of this species from north-western Ghana. 20 Navors. nas. Mus., Bloemfontein, Volume 29, Part 2 MATERIALS AND METHODS Characters important for identification purposes were examined, for the most part with the aid of a stereo-microscope, according to the methods of Gans (1959). Ventrals were counted according to Dowling (1951) with additional typical ventrals (often called pre- ventrals) indicated after a plus sign (see below). The total count was used by Gans (1959; i.e. all distinctly widened ventral plates behind the second pair of chin shields, excluding the anal plate). Both sides of the head were examined and scale counts are presented for one side only unless there was variation between left and right sides. Dorsal saddles (equivalent to Gans’ 1959 ‘pattern cycles’) were counted from the nape to above the vent. Sex was determined by presence of testes or hemipenes (males) or eggs (female). An additional specimen (USNM 223931) of Dasypeltis confusa from Ghana was located at the National Museum of Natural History, Smithsonian Institution (Washington, D.C.). For this specimen, measurements as well as ventral, subcaudal and midbody scale row counts, were provided by J. Jacobs. Detailed photographic images of this specimen (male, right hemipenis everted) were provided by J. Poindexter II, and these allowed accurate examination of head shields. RESULTS AND DISCUSSION Scalation For all specimens of Dasypeltis confusa (locality details follow below): nasal divided below the nostril (divided above and below nostril on both sides of head in BM 1966.265, and on right side only in BM 1977.755); temporals on either side of head 2+3 or 2+4 (3+3 on right side in MHNH 1965.37); preoculars 1; postoculars 2 (but one on left side of BM 1973.2250, and one on right side of USNM 223931); supralabials usually 7 (3rd and 4th enter orbit), but 6 (3+4) in BM 1973.2250; frontal shield smooth except for a single row (two rows in BM 1982.433) of shallow pits on the outer margins; inter-prefrontal sulcus usually weakly developed with prefrontals merely in contact, but moderately developed in BM 1966.265 and BM 1973.2251; 2-4 rows of lateral dorsal scales serrated (usually 3rd to 5th or 6th row, but 4th and 5th rows only in BM 1966.265, and 4th to 6th rows in BM 1977.755). Nigeria BM 1977.755 – female (gravid with nine eggs, six evident in body plus three found in jar) – Vom, SSW of Jos, Plateau State (09°44’N, 08°47’E, c. 1250-1320 m a.s.l.), collected 25 November 1976 by D.P. Britt. Ventrals 227+1, paired subcaudals 57, midbody scale rows 27, dorsal saddles 54. BM 1966.265 – male (swollen testes) – Zonkwa, Kaduna State (09°47’N, 08°17’E, c. 856 m a.s.l.), collected by G.T. Dunger. Ventrals 217+1, paired subcaudals 75, midbody