Friday, October 21, 2016

Slug-eating Snake, Sibon nebulata (Family Dipsadidae)

Other common names: Mapepire corde violin, fiddle string mapepire; cloud snake, cloudy snake.

Size: 440 mm SVL; 158 mm tail; total length about 1 meter. Identification: A medium sized, gray to brown blotched snake with a mottled pattern; body slightly compressed, slender forebody, wide head, large eyes. Smooth dorsal scales in 15 rows, not reduced posteriorly; the vertebral row is slightly enlarged (scales about 1.5 times wider than lateral scales). Rostral barely visible from above, nasals divided, loreal contacts the orbit; preocular usually absent; postoculars two; upper labials 7−8, 4−5 or 5−6 in orbit, 2−3−4 usually contact the loreal; lower labials 8-10; ventrals 169−182 in Trinidad and Tobago specimens, not sexual dimorphic, subcaudals in males 89−113, in females 84−90. Three pairs of chin shields, the first pair in contact with five or six lower labials.  The only Trinidad and Tobago snake with 15 rows of smooth scales rows at midbody, a slightly enlarged row of vertebral scales, and a mental groove. The dorsum is usually gray with 36−41 brown to black blotches. Most easily confused with Dipsas trinitatis which lacks the mental groove; and with Imantodes cenchoa, an extremely slender snake with 17 scale rows at mid-body. This is a widespread species, ranging from Veracruz and Nayarit, Mexico, to Brazil and Ecuador. S. n. nebulata occurs in the northern portion of this range, including Trinidad, Tobago and the Bocas. Habitat: Forests and forest edge; may be found on the ground, but mostly arboreal, climbing several meters above in vegetation; frequently found along streams. It will also use second forest and agricultural areas.  Biology: Nocturnal. May spend daylight hours coiled in epiphytic plants or on the ground in leaf litter. Diet: snails and slugs; this snake is not as specialized as Dipsas for feeding on snails, but it does have elongated maxillary teeth directed medially in the horizontally plane, a character associated with gastropod predation. This is perhaps the most frequently encountered snake during the wet season.  Reproduction: Females lay 3−9 eggs from May through September. Predation by the crab Eudaniela garmani has been reported. 

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