MACROCALAMUS JASONI GRANDISON, 1972

JASON’ S REED SNAKE

(FIGS 16, 17)

Macrocalamus jasoni Grandison, 1972: 45–101 .

Macrocalamus jasoni: Das, 2010: 285; Grandison, 1978: 289; Tweedie, 1983: 61; Manthey & Grossmann, 1997: 367, fig. 136; Norsham & Lim, 2002: 83–89; Vogel & David, 1999: 317; Zakaria et al., 2014: 342.

Holotype: BM 1967.2283. Type locality: ‘ On track below camp 5 at about 5800 feet, Gunong Benom, Pahang, West Malaysia’ = Mt. Benom, 1770 m, Pahang, Malaysia.

Diagnosis: Adult females reach 692 mm SVL, 752 mm TL. Body large, stout; head elongate, triangular, depressed, indistinct from neck; snout rounded; elongate loreal present; one preocular; one postocular; 1 + 2 temporals; eight supralabials, second, third and fourth touching loreal, fourth and fifth touching eye, seventh the largest; seven infralabials; 15 dorsal scales rows at midbody; dorsal scales smooth; ventrals 131– 133 (females); cloacal scale single; 19–22 subcaudals (females) (Grandison, 1972; Vogel & David, 1999).

Coloration in life: Dorsum deep iridescent black, with dorsolateral yellow stripes extending from the nape to the tip of the tail, where they converge. These dorsal stripes are located on the fifth, sixth and seventh dorsal rows and are ~1.5 to two scales wide and sometimes broken up by a length of one or two scales. The head is brownish yellow, tip of snout lighter. There are darker markings on the prefrontals, loreal, pre- and postoculars, anterior temporals and labials, except for the sixth supralabial, which is entirely yellow. Along the posterior edges of the eighth supralabial to the seventh infralabial there is a faint vertical streak. The mental and chin shields are yellowish with black markings, and there are black spots on the third and seventh pairs of infralabials. The throat, neck and venter up to the middle of the flank are yellow. The lateral margins of the ventrals are black. There is some variation in the ventral pattern between the types, from being uniform yellow or marked with black along the middle throughout the length of the body or confined only to the anterior of the body, which gives the appearance of a broad, discontinuous median stripe most prominent anteriorly (Grandison, 1972; Vogel & David, 1999).

Distribution: Known from only the type locality at Gunung Benom, Pahang, Peninsular Malaysia.

Natural history: Grandison (1972) noted that M. jasoni is a montane species recorded between 1770 and 1980 m a.s.l. All specimens were collected from leaf litter on the forest floor in damp habitat or while abroad crossing the trails. Nothing is known of their diet. The holotype was gravid when collected during early April.

Relationships: This is the largest species of Macrocalamus . Owing to the large size and patterning, with the predominantly black dorsum and bright yellow belly, it is hypothesized to be related to the large M. gentingensis and M. schulzi, with which it shares the dorsal and ventral colours, respectively.

Material examined: Peninsular Malaysia, Pahang, G u n u n g B e n o m B M 1 9 6 7. 2 2 8 3 – 1 9 6 7. 2 2 8 5 (photographs only).