Psammophis rukwae, Broadley, 1966

Trape, Jean-François, Crochet, Pierre-André, Broadley, Donald G., Sourouille, Patricia, Mané, Youssouph, Burger, Marius, Böhme, Wolfgang, Saleh, Mostafa, Karan, Anna, Lanza, Benedetto & Mediannikov, Oleg, 2019, On the Psammophis sibilans group (Serpentes, Lamprophiidae, Psammophiinae) north of 12 ° S, with the description of a new species from West Africa, Bonn zoological Bulletin 68 (1), pp. 61-91 : 66

PSAMMOPHIS RUKWAE Broadley, 1966

Rukwa Whip Snake, Psammophis du Rukwa, Rukwa-Sandrennnatter

Psammophis sibilans sibilans (not Linnaeus) Loveridge, 1940: 30 (part); 1956: 48 (part); Perret, 1961: 136; Roussel & Villiers, 1965: 1528; Graber, 1966: 141.

Psammophis sibilans (not Linnaeus) Boulenger, 1896: 161 (part); Sternfeld, 1908b: 218, 233; 1909a: 21; 1917: 478; Böhme, 1975: 40; Hughes, 1983: 353 (part); Chippaux, 2006: 175 (part); Chirio & Ineich, 2006: 52; Chirio & LeBreton, 2007: 534.

Psammophis subtaeniatus (not Peters) Loveridge, 1933: 254 (part).

Psammophis subtaeniatus sudanensis (not Werner) Vesey-FitzGerald, 1958: 62, Pl. 17; Robertson et al., 1962: 428.

Psammophis sibilans rukwae Broadley, 1966: 3 . Type locality: Kafukola , Rukwa valley, Tanzania. Holotype: NMZB 4212.

Psammophis rukwae Cadle, 1994: 119 ; Brandstätter, 1995: 151; Spawls et al., 2002: 406.

Psammophis rukwae rukwae Broadley & Howell, 1991: 28 .

Description. (127 specimens examined) Nostril pierced between 2 nasals; preocular 1 (very rarely 2), in short contact with or separated from frontal; postoculars 2; temporals basically 2+2+3, but with frequent fusions; supralabials 8 (very rarely 9), the 4 th & 5 th (very rarely 5 th & 6 th) entering orbit; infralabials usually 11 (rarely 10 or 12), the first 5 (very rarely 4) in contact with anterior sublinguals; dorsal scales in 17-17-13 rows; ventrals 160–184 (Rukwa type series 165–177; populations East of 25°E 160–184; Chad 169–177; up to 192 for Somalia, but probably a cryptic species); cloacal divided; subcaudals 71–102 (Rukwa type series 83–96; populations East of 25°E 71–100, Chad 84–102 (n=30). Brandstätter (1995, figs 63, 64) has published SEM micrographs of a dorsal scale of the holotype NMZB 4212.

Top of head with a pale median stripe which forks and then borders the frontal, but the head may become uniform yellow-brown in large adults; labials immaculate or with large brown spots; dorsum dark or light brown, rarely uniform, most specimens with at least a vertebral chain, each scale in vertebral row paler at base. Some specimens have ill-defined pale dorsolateral stripes on scale rows 4 and 5, which fade out in some adults, but many other specimens, including large adults, have both well contrasted vertebral chain, with black pigment on each side of the scales of the vertebral row, and well contrasted pale dorsolateral stripes on scale rows 4 and 5 with black pigment on each side. Lower half of outer scale row and ends of ventrals yellowish, separated or not by a pair of brown or blackish ventral lines from a yellow mid-ventral band.

Size. Largest specimen (TM 25301 – Kafukola, Rukwa, Tanzania) 1,090 + 388 = 1,478 mm.

Remarks. According to Broadley (1966) P. rukwae was a subspecies of P. sibilans distinguished by consistent ventral pattern of a pair of black lateral hairlines similar to that found in P. subtaeniatus . However our series of specimens from Chad show that many specimens lack black lateral hairlines.

Habitat. Flood plains and grasslands seem to be the preferred habitats in eastern Africa. In Chad this species is common in all types of savannas.

Distribution. East Africa from the Rukwa valley in Tanzania, north through Kenya, Uganda, Ethiopia, South Sudan and Sudan, then the western populations extend from the Central African Republic and Chad west to northern Cameroon.