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PSAMMOPHIS AFROCCIDENTALIS Trape, Böhme & Mediannikov, sp. nov.

Description and pictures from Trape e.a. 2019

 

Psammophis afroccidentalis sp. nov. Plain phase. Sequenced specimen IRD TR.4501. Matmata (Mauritania). Psammophis afroccidentalis sp. nov. Lineated phase. Dakar (Senegal).

 

Names West-African Whip Snake, Psammophis ouest-africain, Westafrikanische Sandrennnatter
Synonym

Psammophis sibilans (not Linnaeus) Boettger, 1881: 395; Boulenger, 1896: 161 (part); Boulenger, 1906: 214; Sternfeld, 1908a: 412; Chabanaud, 1918: 165; Angel, 1933a: 69; 1933b: 162, fig. 61; Andersson, 1937: 8; Cansdale, 1949: 106; Hughes & Barry, 1969: 1023; Roman, 1980: 61; Chippaux, 2006: 175 (part); Trape & Mané, 2000: 26; 2002: 149; 2004: 21; 2015: 45; Villiers & Condamin, 2005: 144; Auliya et al., 2012: 280; Hughes, 1983: 353 (part); 2012: 123; 125 (ZFMK 29365 from Tamanrasset); Chirio, 2012: 83; Trape & Baldé, 2014: 317.

Psammophis trinasalis (not Werner) Chabanaud, 1918: 166 (Senegal).

Psammophis sibilans sibilans (not Linnaeus) Loveridge, 1940: 30 (part); Leston 1950: 84; Villiers, 1950: 93; 1951: 827; 1952: 892; 1953: 1119; 1954: 1242; 1956a: 880; 1956b: 158; 1963: 1372; 1975: 138; Condamin, 1958: 255; Doucet, 1963: 306.

Psammophis phillipsii (not Hallowell) Böhme, 1978: 398, Fig. 16, 17 (right); 2000: 71.

Psammophis rukwae (not Broadley) Böhme, 1978: 401; 1987: 259; Brandstätter, 1995: 151 (part); Chirio, 2009: 30.

Psammophis cf. rukwae (not Broadley) Joger, 1981: 332; 1982: 332; Gruschwitz et al., 1991: 30.

Psammophis cf. phillipsii (not Hallowell) Schätti, 1986: 771; Böhme et al., 1996: 21; Rödel et al., 1995: 7; 1999: 170; Ullenbruch et al., 2010: 43.

Psammophis sudanensis (not Werner) Ullenbruch et al., 2010: 44; Chirio, 2012: 83.

Psammophis aff. sibilans (not Linnaeus) Trape & Mané, 2017: 120.

 
Holotype MNHN 2018.0013 (formerly IRD 7631.S, a male from Dakar Hann, Senegal (14°43’N, 17°26’W) collected by J.-F. Trape on December 10th, 2005 (Figs. 13 & 14).
Diagnosis Distinguishable from other species of the P. sibilans group by the combination of the following characters: 17 scale rows around midbody, 156–185 ventrals, 96–120 subcaudals (rarely less than 100), cloacal divided, 5 infralabials in contact with anterior sublinguals (very rarely 4). Dorsum pale brown, dark brown or greenish-brown, rarely uniform, usually a vertebral chain with the scale of vertebral row paler at base, but this chain often restricted to part of the dorsum, ill-defined and occasionally totally absent; pale dorsolateral stripes on the 4th row of dorsals, but often ill-defined or absent; top of head with a pale median stripe on the snout which forks when reaching the frontal and then borders the frontal, but often ill defined or absent in adults. Genetically diagnosable through possession of unique mitochondrial haplotypes. Psammophis afroccidentalis sp. nov. can be distinguished from P. rukwae by a higher number of subcaudals (P. rukwae 70–100, exceptionnaly up to 105), from P. sibilans by major differences in mitochondrial haplotypes, a pale median stripe that borders the frontal (not bordering the frontal in P. sibilans) and a more uniform dorsal colouration in most specimens, from P. schokari and P. aegyptius by a lower number of subralabials (8 versus 9) and a different head pattern, and from P. sudanensis, P. phillipsi, P. occidentalis, P. mossambicus, P. leopardinus, P. zambiensis and P. subtaeniatus by a higher number of infralabials in contact with the anterior sublinguals (5 versus 4) and by different head and dorsal patterns.
Description of holotype

A male specimen, snout-vent length 745 mm, tail length 345 mm, total length 1090 mm, ratio total length: tail length 3.16. Supralabials 8/8 supralabials, 4th & 5th entering orbit (Fig. 15); 11/11 infralabials, first 5 contact anterior sublinguals; 1/1 preocular contacting frontal; 2/2 postoculars; 2/2 anterior temporals (the lower one on right side divided); 2+3/2+3 posterior temporals. Scale rows 17 around hood, 17 around midbody, 13 one head length ahead of the vent, all smooth and oblique. Dorsal scales smooth, oblique. Vertebral row not enlarged. Ventrals 168 (Dowling: 167), subcaudals 104, all divided, cloacal divided.

Top of head with a pale median stripe on the snout which forks and then borders the frontal; labials pale brown and yellowish. Dorsum uniform brown except pale dorsolateral stripes on scale rows 4 and adjacent parts of rows 3 and 5. No vertebral chain. Belly yellowish, limit with dorsal colouration on the first row of dorsals; traces of broken brown hairlines on part of the ventrals.

Etymology The name is derived from the contraction of Africa and occidentalis, the region of Africa where this species is distributed.
Variation

(924 specimens examined) Nostril pierced between 2 nasals; preocular 1, in contact with or separated from frontal; postoculars 2; temporals basically 2+2+3 with occasional fusions or divisions, supralabials 8, the 4th & 5th entering orbit; infralabials usually 11 (rarely 9 or 10), the first 5 (very rarely 4, 2% of specimens only) in contact with anterior sublinguals; dorsal scales in 17-17-13 rows; ventrals 156-165.9-180 in males; 160- 173.2-185 in females, cloacal divided; subcaudals 98- 108.0-121 in males, 96-106.2-120 in females.

Colouration variable (Figs 4, 5, 16, 17). Top of head pale brown with a pale median stripe on the snout which forks and then borders the frontal, but the head often becomes uniform brown in adults; labials immaculate or with brown spots; dorsum from light brown to dark brown; a vertebral chain rarely absent but often ill-defined, with most scale in vertebral row paler at base and rarely black edged; pale dorsolateral stripes on scale row 4 either well contrasted, ill-defined or absent; belly light yellowish, often immaculate but occasionally with hairlines.

Largest intact specimen (IRD 3538.S – Matam, Senegal) 1,145 + 460 = 1,505 mm, but largest SVL = 1,260 mm in two specimens with truncated tails (IRD 3345.S – Jalalawy, Senegal, and IRD 3345.S – Matam, Senegal).

Remarks There are limited molecular differences between a mainly western group of specimens (Senegal, Mauritania, Mali, Guinea, Ivory Coast and one o`f the two specimens from Niger) and those from Burkina Faso, Benin, Niger, and Mao in Chad. They are not correlated to differences in colour patterns nor in meristic data.
Habitat Sahel and Sudan savanna in West Africa. Penetrates in Guinea savanna and relict populations in sahelo-saharan wetlands.
Distribution Mauritania (northernmost record: Tidra island 19°44’N, 16°24’W), Senegal, Gambia, Guinea Bissau, Guinea, Mali (northenmost record: Tinjemban 16°44’N, 02°50’W and along the Niger River), Ivory Coast, Burkina Faso, Ghana, Togo, Benin, Niger (northernmost record: Azzel 17°03’N, 08°03’E), Nigeria and Chad (Mao). Possibly a relict population in southern Algeria (ZFMK 29365 from 200 km north of Tamanrasset, a damaged specimen previously assigned to P. rukwae by Böhme 1986 and to P. sibilans by Hughes 2012).

 

Fig. 12 of Trape e.a. 2019. Geographic distribution of the sequenced specimens of P. sibilans and other species frequently confounded with P. sibilans: P. phillipsi, P. mossambicus, P. rukwae, P. sudanensis, and P. afroccidentalis sp. nov. One symbol may correspond to several specimens from neighbouring localities. Location of type locality is approximate for P. sibilans ("Egypt"), P. phillipsi ("Liberia") and P. mossambicus ("insel Mossambique").

 

Fig. 13 of Trape e.a. 2019.  Psammophis afroccidentalis sp. nov. General view of the holotype MNHN 2018.0013 (formerly IRD 7631.S) from Dakar, Senegal.

Fig. 15 of Trape e.a. 2019. Psammophis afroccidentalis sp. nov. Lateral (A), dorsal (B) and ventral (C) view of the head of the holotype MNHN 2018.0013 from Dakar, Senegal.

Fig. 14 of Trape e.a. 2019. Psammophis afroccidentalis sp. nov. Ventral view of the holotype MNHN 2018.0013 from Dakar, Senegal.