Friday, August 26, 2016

Water Mapapie, Helicops angulatus (Family Dipsadidae)

Other common names: Banded Water Snake; Water Snake, Brown Banded Water Snake.
Size: Males 475 mm, female reach and probably exceed 625 mm; tail 31−43% SVL.
Identification: Head broad, eyes dorsolateral; body stout; dorsum red-brown with 20–27 dark brown cross bands on body and 15–20 blotches on tail; dark blotch on nape may fuse to first cross band. Venter tan or pink with dark brown bands that usually coincide with dorsolateral bands. Rostral visible from above pentagonal; nasal divided and separated by two internasals; prefontals paired; eyes small and directed more dorsally; loreal single and in contact with the second and third labials; one preocular; two postoculars; two primary temporals and three secondary temporals; 7–9 upper labials, sixth largest, and fourth enters the orbit; 7–10 lower labials; anterior chin shields longer than the second pair and the anterior pair contacts the first five lower labials; 114–121 ventrals; anal plate divided; 63–72 paired subcaudals. Keeled, striated and elongated dorsal scales in 19 rows at mid-body, reduced posteriorly to 17 rows; these characteristics distinguish this snake from all other Trinidad snakes. Juveniles with dark brown blotches four or five scale rows wide on dorsal midline and separated by light tan bands, one or two scale rows wide on mid-line. Dark bands narrow toward venter, light bands widen toward venter.
Similar Species: Trinidad and Tobago have few snakes that have a dorsal pattern of transverse bands and keeled scales, the coral snakes and their mimics have bands, but they tend to be slender, smooth scaled snakes. But, Linne’s Swamp Snake has bands when young but it has 17 scale rows, and the Water Coral has triangular-shaped markings and its pattern also contains red, but it has 15 rows of dorsal scales.

Habitat: An aquatic snake found in herbaceous swamps; ponds, ditches, slow moving; streams; rice paddies; flooded pastures.

Natural History: Nocturnal. Diet includes lizards, fish, and frogs. Reproduction clutch sizes are 8–18; some populations of this snake may be facultative ovoviviparous; incubation is 39−45 days. We found a clutch of eight eggs beneath corrugated tin about 10 meters from a water filled ditch in September.

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