Crotaphopeltis degeni (Boulenger, 1906)

Rasmussen, Jens Bødtker, Chirio, Laurent & Ineich, Ivan, 2000, The Herald Snakes (Crotaphopeltis) of the Central African Republic, including a systematic review of C. hippocrepis, Zoosystema 22 (3), pp. 585-600 : 591-594

Crotaphopeltis degeni (Boulenger, 1906)

Leptodira degeni Boulenger, 1906: 572 .

SYNTYPES. — Entebbe, Uganda, 1 male and 1 female respectively (BMNH 1946.1.9.96-97).

Crotaphopeltis degeni Barbour & Amaral 1927: 26 . – Rasmussen 1997: 192 (review).

DIAGNOSIS

A semiaquatic species of Crotaphopeltis of the Central African Plateau with the following character combination: 19 scale rows at mid-body, dorsal scales smooth all over the body; 15-19 + II maxillary teeth; 31-41 (male) and 25-38 (female) subcaudals; hemipenis extending to subcaudal scute No. 7-11 and usually provided with five enlarged spines proximally; dorsum dark brown, grey or almost black, no white specks or temporal marks, pigment on lower jaw usually restricted to the last infralabial; venter cream or pale yellowish; underside of tail whitish, with a more or less distinctly pigmented, median stripe, usually but not always, starting just behind the anal shield.

DESCRIPTION OF SPECIMENS

FROM THE CENTRAL AFRICAN REPUBLIC

Lepidosis

Rostral 1.7-2.0 times as broad as deep, in narrow contact with internasals; frontal 1.3-1.5 time as long as broad (see Table 1), 1.0-1.2 time as long as its distance from end of snout, and 0.9-1.1 time as long as suture between parietals; one loreal, distinctly longer than deep, in contact with eye below preocular on left side in one specimen; one preocular, rarely two ( Table 1); two postoculars, rarely one ( Table 1); usually 1 + 2 temporals (for variation see Table 1); usually eight supralabials, third to fifth usually entering orbit (for variation see Table 1); usually 10 infralabials, first five on each side usually in contact with an anterior chin-shield (for various combinations see Table 1); three to five pairs of chinshields and enlarged median gulars (for variation see Table 1) followed by zero to four preventrals. Dorsal scales smooth with well defined single or double apical pits. Scale row formula of the body usually 17-19-15. Scale row reduction formula (tail) as follows:

8 (3-5) - 6 (5-13) - 4 (15-25) - 2 (26-41) male (n = 11) and 8 (2-5) - 6 (5-8) - 4 (12-20) - 2 (29- 35) female (n = 10).

Ventrals rounded, 161-173 in male (n = 11), and 163-172 in female (n = 10); anal entire; subcaudals paired, 31-41 in male (n = 10), and 31-37 in female (n = 10).

Dentition

Maxillary teeth 14-16 + II (x = 15.6, s = 0.7, n = 21); palatine teeth 10-12 (x = 11.0, s = 0.3, n = 19). No sexual dimorphism in either count.

Dimensions

Total length of largest male 65 cm; largest female 60 cm.

Hemipenes

In situ the organs extend to subcaudal scute No. 8-10 (x = 8.8, s = 0.6, n = 10). In everted condition the hemipenes of specimens from the nearby Sudan are characterised by the possession of up to six enlarged spines at the lower truncus (Rasmussen 1997).

Internal morphology

Tongue sheath extending to ventral scute (VS) No. 15-16 in male (n = 10), 12-14 in female (n = 10), giving relative position 8.7-9.9% VS in male and 7.2-8.3% VS in female.

Tip of heart extending to ventral scute No. 33-35 in male (n = 10), 33-37 in female (n = 10), giving relative positions 20.2-21.2% VS in male and 19.8-21.5% VS in female.

Anterior end of liver situated at VS No. 43-46 in male (n = 9) and 40-46 in female (n = 10), giving relative position 25.8-27.5% VS in male and 24.5-27.0% VS in female. Absolute distance heart tip to anterior end of liver 9-11 VS in male and 6-10 VS in female.

Right kidney longer than left; absolute length (right/left) 22-27/17-22 VS in male (n = 7) and 19-25/16-20 VS in female (n = 7), giving relative lengths 13.7-16.1/10.6-13.1% VS in male and 11.4-15.0/9.5-12.3% VS in female. Anterior end of kidneys situated at VS No. 131-136/ 137-142 in male, 133-142/ 137-147 in female, giving relative position 79.8-82.0/82.7-85.7% VS in male and 80.8-85.0/84.1-87.5% VS in female. Posterior ends of kidneys situated at VS No. 154-161/ 155- 162 in male and 156-165/ 157-166 in female, giving relative position 95.2-95.8/95.8-96.4% VS in male and 95.7-96.5/96.3-97.1% VS in female.

Anal glands extending to subcaudal scute No. 3-5 in male (x = 3.7, s = 0.7, n = 9) and to 4-5 in female (x = 4.3, s = 0.5, n = 10).

Coloration (in life)

Dorsum uniform slate grey, belly and underside of tail white, a pale yellow line separating dorsal and ventral colours. Temporal region, including last two supralabials and the last infralabial, same colour as upper side of head.

Coloration (in preservative)

Dorsum grey-brown, grey or almost black. Belly and lower row of dorsals whitish or pale cream, underside of tail whitish with a more or less distinctly pigmented, median stripe which usually, but not always, begins just behind the anal scale. Lips white or pale cream, supralabials and posterior infralabial becoming pigmented with increasing size.

Biology

Crotaphopeltis degeni has eyes of moderate size (greatest horizontal diameter of eye 0.6-0.8 [x = 0.7, s = 0.1, n = 15] time length of snout) and vertical pupils, thus indicating a nocturnal way of life as in other Crotaphopeltis species. The eyes, however, are smaller than in the two other species of the country.

In Central African Republic C. degeni occurs in the Sudano-Sahelian savanna where it lives sympatrically with C. hotamboeia . A female measuring 50 cm contained six eggs. The few facts known about its habitats were recently described by Rasmussen (1997).

Distribution

Crotaphopeltis degeni has a disjunct distribution in Ethiopia, Sudan, Uganda, Kenya, Tanzania, Cameroon and in the eastern part of Central African Republic ( Fig. 2 ).

Localities and material examined

Central African Republic. Am Dafok, MNHN 1996.6494, 1997.3523-28, 1998.229-39. — Birao, MNHN 1997.3529-30. — Dahal Azrak (near Dahal Hadjer), MNHN 1996.6495.

Geographical variation

Rasmussen (1997) compared the various populations of C. degeni ; however, only two of these were well-represented, i.e. the Kenyan and the Sudan populations. With respect to the number of ventrals, the specimens from Central African

Crotaphopeltis (Serpentes) of the Central African Republic

Republic have intermediate values compared to these countries; in males this is also the case with respect to the number of subcaudals, whereas the females have values similar to those of the Sudan population. The number of maxillary teeth and relative position of heart in both sexes have values lower than those in the populations of Sudan and Kenya. The present findings thus seem to support the view that much of the variation of the various characters in this species is discordant.

REMARKS

The distribution of C. degeni is somewhat similar to the bizarre and seemingly disjunct distribution of Causus resimus Peters, 1862 (Spawls & Branch 1995).

Figures

FIG. 2. — Distribution of Crotaphopeltis degeni () and Crotaphopeltis hippocrepis (). Regarding the Tanzanian record of C. hippocrepis, see text.