Showing posts with label worm snakes. Show all posts
Showing posts with label worm snakes. Show all posts

Sunday, March 20, 2011

A New Brazilian Leptotyphlopid, and the Status of Leptotyphlops brasiliensis Laurent



The Neotropical leptotyphlopid 
Epictia tenella (Klauber) was previously 
considered a member of the albifrons
Group. JCM
Until recently the burrowing worm snakes of the genus Leptotyphlops comprised 114 species inhabiting mostly Africa and the Neotropics. The genus was recently divided into 10 different genera by Adalsteinsson et al. (2009). In South America about 40 species of leptotyphlopids occurred from Colombia to Argentina. Their strictly fossorial life style was supported by a compactly built skull, smooth scales, and reduced eyes covered by an ocular plate. All of these highly specialized snakes have a diet of small invertebrates and have highly derived, short mandibles and a highly kinetic mandibular joint. In 1970, Peters and Orejas-Miranda recognized five groups of Neotropical worm snakes based on appearance: L. albifrons, L. dulcis, L. melanotermus, L. septemstriatus, and L. tesselatus species groups. The L. septemstriatus species group was diagnosed by absence of supraocular scales and included L. borrichianus, L. brasiliensis, L. cupinensis, L. nasalis, and L. septemstriatus. Previously, Laurent (1949) had described L. brasiliensis, and 45 years later, Rodrigues and Puorto (1994) described a second specimen from Barreiras, state of Bahia. One of the most important features supporting the identification of this second individual was the absence of supraoculars, a characteristic emphasized by Laurent (1949) in the original description. However, the specimen of Rodrigues and Puorto (1994) did not agree with the holotype regarding supralabial number, because Laurent noted only two supralabials scales (1+1), whereas the specimen from Barreiras had three (2+1) distinct supralabials bordering the mouth. Wallach (1996) reported a third specimen from the same locality as that of Rodrigues and Puorto (1994), restricting the type locality of the species to Barreiras, state of Bahia, Brazil. Curcio et al. (2002) recorded four specimens of L. brasiliensis from the Brazilian Cerrado (central Brazilian savannas) of southwestern Piau─▒´ State, all with three supralabials. In view of the differences in supralabial counts between the holotype and the other known specimens of L. brasiliensis, these authors claimed that larger samples would allow more precise conclusions regarding the variation of this character.

Roberta Pinto and Felipe Curcio (2011) have now describe the geographic variation and hemipenial morphology of Leptotyphlops brasiliensis Laurent using 23 specimens, and re-examine its generic identity. They propose the new combination, Tricheilostoma brasiliensis, noting that the presence of two supralabials, as mentioned in the original description of S. brasiliensis, is not a common feature for this species. They also describe a new species of worm snake Siagonodon acutirostris from the savannas of the state of Tocantins, Brazil. The new species differs from others in the same genus by having an acuminate snout in lateral and ventral views, sub-circular rostral in dorsal view, and 12 scale rows around middle of tail.

Citation
Pinto, R. R. and F. F. Curcio. 2011. On the Generic Identity of Siagonodon brasiliensis, with the Description of a New Leptotyphlopid from Central Brazil (Serpentes: Leptotyphlopidae). Copeia (1):53-63.