Tuesday, October 22, 2013

A new snake species from Tobago


Until now two snake species of the genus Leptophis (parrot snakes) have been known to  inhabit Trinidad and Tobago. One, L. stimsoni, is endemic to Trinidad’s Northern Range and known from relatively few specimens. The second is the diurnal, arboreal, brightly colored parrot snake Leptophis coeruleodorsus.

The genus Leptophis was first reported in Trinidad and Tobago by Reinhardt & Lütken (1862), and while it appeared on lists, no natural history information was reported until Mole (1924) described its diet. Oliver described the Trinidad & Tobago populations of Leptophis as  L. coeruleodorsus in 1942, and in 1948 re-classified it as a subspecies of L. ahaetulla. Oliver viewed Leptophis ahaetulla as a species with 147–183 ventrals, 135–185 subcaudals, 18–28 maxillary teeth, and a distribution extending from about 22º N latitude to 35ºS latitude (a straight line north-south distance of about 7500 km). Oliver’s 13 subspecies were based primarily on coloration, as well as ventral and subcaudal counts and he viewed much of the morphological variation as clinal.

The second known species of Leptophis on Trinidad is Leptophis stimsoni Harding, a Northern Range endemic and a member of the L. riveti Group. The first specimen was collected by Sanderson in 1937 from the summit of Mt. Aripo (Cerro del Aripo), and was considered to be L. riveti  by Emsley (1977). No other specimens were known until 1987 when two specimens, one from the Arima Valley and another from Cumaca Cave were collected. Harding (1995) described L. stimsoni as distinct from L. riveti.

Murphy et al. (2013) compared 11 specimens of the L. ahaetulla Group using DNA sequences from two mitochondrial genes (cytochrome b and 16S, 1,383 bp total) from island and mainland populations, reported on the variation in the morphology of 54 museum specimens of Leptophis a. coeruleodorsus; restrict the type locality of L. coeruleodorsus to Mt. St. Benedict; and they describe a new species of Leptophis from the island of Tobago that can be distinguished from L. coeruleodorsus on the basis of snout shape, upper labial architecture, elongated prefrontal scales, and ventral scale counts.

Leptophis haileyi is the only Tobago Leptophis to have a subacuminate snout in profile; the rostral is barely visible from above; the primary temporal is in contact with three or four upper labials, including the last; prefrontal scale is long, it has a high ventral count (173) and it is a male, with a tail/SVL ratio that falls with in the range of female L. coeruelodorsus.   All L. coeruleodorsus examined have two upper labials contacting primary temporal with last upper labial excluded from contact with primary temporal.
(a) Leptophis coeruleodorsus (b) L. haileyi
The new species is currently known from a single specimen from the northeast portion of Tobago in the vicinity of Roxborough and is named in honor of Adrian Hailey for his work on the Trinidad and Tobago herpetofauna. This description raises the number of endemic Tobago amphibians and reptiles to 11 taxa.

Citation
MURPHY, J. C., CHARLES, S. P., LEHTINEN, R. M., & KOELLER, K. L. (2013). A molecular and morphological characterization of Oliver’s parrot snake, Leptophis coeruleodorsus (Squamata: Serpentes: Colubridae) with the description of a new species from Tobago. Zootaxa, 3718(6), 561-574.

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