On the Generic Identity of Siagonodon brasiliensis, with the Description of a New Leptotyphlopid from Central Brazil (Serpentes: Leptotyphlopidae)
The geographic variation and hemipenial morphology of Siagonodon brasiliensis are described based on a comprehensive sample, allowing the reappraisal of its generic identity, and the proposal of a new nomenclatural combination. We suggest that the presence of two supralabials, as mentioned in the original description of S. brasiliensis, is not a common feature for this species, occurring at low frequencies throughout its geographic distribution. Based on a diagnosis presented in a recently published paper, as well as on additional external traits and on hemipenial characters, we recognize Siagonodon brasiliensis as a species of the genus Tricheilostoma. In addition, a new species of worm snake of the genus Siagonodon is described from the savannas of the state of Tocantins, Brazil. The new species differs from other congeners by having a slightly acuminate snout in lateral and ventral views, subcircular rostral in dorsal view, and 12 scale rows around middle of tail. The diagnosis of the genus Siagonodon is revised and expanded based on direct observation of morphological characters.
Schematic views of the dorsal surface of the tail of leptotyphlopid snakes: (A) fused caudals on tail tip (T. brasiliensis), and (B) non-fused caudals on tail tip (S. acutirostris). Scale = 5 mm.
Dorsal (A), lateral (B), and ventral (C) views of the head of the holotype of Tricheilostoma brasiliensis. Scale = 5 mm.
Sulcate (A), asulcate (B), and lateral (C) views of the hemipenis of T. brasiliensis (UFMT 1162). Scale = 5 mm.
Geographic distribution of Siagonodon acutirostris and T. brasiliensis. Triangles = S. acutirostris (white triangle represents the type locality); circles = T. brasiliensis (1 = type locality sensu Wallach, 1996; 2 and 3 = range extensions reported by Pinto et al., 2005 and Curcio et al., 2001, respectively). Darkened area represents the borders of the Brazilian Savannas domain.
Photographs of the holotype of Siagonodon acutirostris in dorsal (A), lateral (B), and ventral (C) views of the head. Scale = 5 mm.
Dorsal (A), lateral (B), and ventral (C) views of the head of the holotype of Siagonodon acutirostris. Scale = 5 mm.
Contributor Notes
Associate Editor: T. W. Reeder.