Friday, September 30, 2011

New Frog Added to Trinidad's Herpetofauna

Scarthyla vigilans from southwestern Trinidad. JCM

The tiny, grass-dwelling frog, Scarthyla vigilans (Hylidae) has been officially added to the herpetofauna of Trinidad. The frog avoided detection of previous researchers investigating the fauna of the continetal island until 2006 when J. Roger Downie and Joanna M. Smith collected striped tadpoles from an irrigation ditch in a coconut plantationin the southwest peninsula of the island. The tadpoles positioned themselves vertically in the water adjacent to submerged grass stems.The tadpoles did not match any of the known species from Trinidad.The tads weighed only 0.26 g and measured about 29 mm. Two adults were collected in 2007, and more were added in 2010. The frogs were discovered in Venezuela's Orinoco Delata in 2008, but were previously known from northeast Colombia and northwest Venezuela. The small size (14-19 mm) of adults, their very insect-like call, and their superficial similarity to the very common and widespread Scinax rubra has contributed to them going undiscovered. The full paper is available on-line.

Smith, J.M.; J.R. Downie; R.F. Dye; V. Ogilvy; D.G. Thornham; M.G. Rutherford; S.P. Charles; J.C. Murphy.2011. Amphibia, Anura, Hylidae, Scarthyla vigilans (Solano, 1971): Range extension and new country record for Trinidad, West Indies, with notes on tadpoles, habitat, behavior and biogeographical significance. Check List 7(5):574-577.

Friday, September 9, 2011

Epicrates maurus

Epicrates maurus. JCM
The Rainbow Boas of the genus Epicrates are widespread in the Caribbean with nine species and another five species that range from Costa Rica to Argentina. Recent molecular work shows the genus to be paraphyletic, and the mainland species will undoubtedly remain in the genus Epicrates while the West Indian forms will probably be placed in another genus, perhaps Fischer's genus Homalochilus that is now in the synonymy of Epicrates striatus.

Recently, Rivera et al. (2011) have analyzed two independent data sets, environmental niche models and phylogeny based on molecular information, to explore species delimitation in the continental species of this genus. Their results indicated that the environmental requirements of the species are different and are not ecological interchangeable. The authors found a correlation between species distributions and the major biogeographic regions of Central and South America. The distribution of the five species reveals that allopatry or parapatry is the general pattern suggesting that habitat isolation prevents or limits gene flow between the species. Their phylogenetic reconstruction shows that the mainland Epicrates are monophyletic and the sister to the anacondas (Eunectes). E. maurus shows a disjunct distribution, and is present in the dry forest of the biogeographic regions Pacific Coast, Venezolana, Savanna, Guajira and some areas in the Amazonic domain, in Central America and Northern South America. On Trinidad and Tobago this snake does quite well in the presence of humans and can be found in urban and agriculture areas, habitat use that might be expected of a species that uses dry forests.

Rivera PC, Di Cola V, Martínez JJ, Gardenal CN, Chiaraviglio M (2011) Species Delimitation in the Continental Forms of the Genus Epicrates (Serpentes, Boidae) Integrating Phylogenetics and Environmental Niche Models. PLoS ONE 6(9): e22199. doi:10.1371/journal.pone.0022199