Purari Groundsnake

biology_ecology

Habitat and Natural History. Like other members of the genus Stegonotus, S. aplini is a nocturnal species that forages on the forest floor at night. This species was common in both primary lowland forest remote from human habitation (Fig. 5), and in garden regrowth near villages; at least ten individuals were observed during surveys of the Purari basin, where the species’ conspicuous pale colouration was readily visible in torchlight during night surveys. During capture each of the specimens struck repeatedly when handled, and attempted again to strike at researchers whilst being extracted from secure holding bags for examination. Local landowners greatly feared this species which they mistook for the highly venomous elapid Micropechis ikaheca 1 (Lesson, 1830), the only other pale, nocturnal snake in the region. All known locations where this species has been located are in the lowlands of the Purari River basin (Fig. 6).

A striking new species of Papuan groundsnake (Stegonotus: Colubridae) from southern Papua New Guinea, with a dichotomous key to the genus in New Guinea

description

Description of holotype. (Figs. 1 A – D, 2 A – B). An adult male, SVL = 1087 mm, TL = 290 mm, TTL = 1377 mm; head distinct from neck, snout rounded in dorsal view, body arch-shaped in cross-section, tail moderately long (TL 21 % of TTL). Dorsal scales in 17 - 19 - 15 rows; 229 ventrals, 89 paired subcaudals, and an entire cloacal plate; SC / (V + SC) ratio = 0.28. Rostral clearly visible when viewed from above, extending back to separate internasals for one-third their depth but not to a point level with the nostrils (shallow V condition; Kaiser et al., 2019). Internasals paired, in broad contact behind rostral. Prefrontals also in broad contact, twice as long and 1.3 times as wide as internasals, extending laterally onto head to contact preoculars, loreal and nasal. Frontal shield-shaped, as broad as long. Supraoculars much broader posteriorly than anteriorly. Parietals twice as long as wide. Nasal almost split by large naris, almost reaching first supralabial. Loreal rectangular, 1.5 times as long as high. Two preoculars, lower largest, nearly equal in length to loreal. Two postoculars, upper larger. Nine supralabials, SL 4 – SL 5 in contact with orbit, SL 6 – SL 7 largest, SL 5

A striking new species of Papuan groundsnake (Stegonotus: Colubridae) from southern Papua New Guinea, with a dichotomous key to the genus in New Guinea

description

urn: lsid: zoobank. org: pub: 49 BEE 762 - 97 B 0 - 4 CD 8 - B 942 - 7241 EB 220138 (urn: lsid: zoobank. org: act: A 759 EDE 944 E 8 - 4 B 99 - A 2 B 5 - F 30 DF 6865 C 96)

A striking new species of Papuan groundsnake (Stegonotus: Colubridae) from southern Papua New Guinea, with a dichotomous key to the genus in New Guinea

diagnosis

Diagnosis. A species of Stegonotus that can be diagnosed from all congeners by the following combination of characters: dorsum of body immaculate snow-white anteriorly, with dark speckling that manifests as occasional brown-tipped scales by midbody and increases in frequency and density posteriorly; tail entirely dark brown with light pigment confined to lowest dorsal scale rows; venter and subcaudal scales off-white; head dorsally dark brown, contrasting with white anterior of the body, brown pigment extending posteriorly for 6 – 20 scales; dorsal scales rows 17 - 19 - 15 (75 %) or 19 - 19 - 15 (25 %), ventral scales 229 – 239, subcaudal scales 83 – 95, all divided; SL usually nine (75 %), occasionally eight (25 %), with SL 4 – SL 5 contacting the orbit; and IL nine (75 %), or eight (25 %) with IL 1 – IL 4 or IL 1 – IL 5 contacting the anterior genials.

A striking new species of Papuan groundsnake (Stegonotus: Colubridae) from southern Papua New Guinea, with a dichotomous key to the genus in New Guinea