Causus bilineatus Boulenger, 1905

Conradie, Werner, Baptista, Ninda L., Verburgt, Luke, Keates, Chad, Harvey, James, Júlio, Timóteo & Neef, Götz, 2021, Contributions to the herpetofauna of the Angolan Okavango-Cuando-Zambezi river drainages. Part 1: Serpentes (snakes), Amphibian & Reptile Conservation (e 292) 15 (2), pp. 244-278 : 271

Causus bilineatus Boulenger, 1905

Two-lined Night Adder ( Fig. 36 , Map 35)

Material: PEM R 23268–70, Cuanavale River source lake, Moxico Province, -13.09330° 18.89396°, 1,367 m asl; PEM R 23321, Cuito River Source Lake, Moxico Province, -12.68935° 18.36012°, 1,435 m asl; PEM R 23428–9, Cuando River Source Trap 2, Moxico Province, -13.00426° 19.12719°, 1,350 m asl; PEM R 23437, Cuando River Source Trap 1, Moxico Province, -13.00393° 19.12808°, 1,351 m asl; PEM R 23451–2, Quembo trap 4, Moxico Province, -13.13586° 19.04709°, 1,368 m asl; PEM R 23464–5, INBAC: WC-4727, Quembo trap 1, Moxico Province, -13.13592° 19.04417°, 1,369 m asl. Additional photographic record: Cuatir, Cuando Cubango Province, -16.48523° 18.20304°, Stefan van Wyk. Description: Dorsal scales smooth and in 17 rows at midbody; 129–135 smooth ventrals; 24–32 paired subcaudals; 2 preoculars; 2 postoculars; temporals mostly 2+3; 6 supralabials; 9 infralabials, the first four in contact with the anterior chin shield; cloacal scale entire. Largest female: 337 + 38 mm ( PEM R 23321); largest male 350 + 53 mm ( INBAC: WC-4727). Habitat and natural history notes: This species is associated with wetlands and rivers. The stomachs of specimens contained various frogs ( Ptychadena taenioscelis , P. uzungwensis , Hyperolius nasutus , and Breviceps ombelanonga ). One female ( PEM R 23429) collected in November 2015 had four fully developed eggs, the largest measuring 12.8 x 6.5 mm. Comment: This species has mostly been recorded from central and western Angola ( Marques et al. 2018) with the only known record from eastern Angola being from Lake Calundo, Moxico Province ( Laurent, 1964). Marques et al. (2018) assigned Bogert’s (1940) C. rhombeatus specimen from Capelongo to C. bilineatus following Manaças (1981), however Rasmussen (2005) examined the same material and assigned it to C. rhombeatus . The recently collected material is the first from the Okavango Delta system. The southernmost record of this species is from Cuatir, Cuando Cubango Province.

Figures

Fig. 36. Causus bilineatus from Quembo River source. Photo by Luke Verburgt.