Redescription ofApostolepis albicollarisLema, 2002, with a Key for the Species Groups of the GenusApostolepis(Serpentes: Dipsadidae: Elapomorphini)

Abstract

Here we provide a detailed description and diagnosis of Apostolepis albicollaris Lema, 2002, a species known from Central Brazil. The species is easily diagnosable from all its congeners by the following combination of characters: a distinctive white nuchal collar (bordered by a narrow black collar), a very broad black lateral streak (from ventral border to 5 th dorsal row), an almost entirely black ventral surface or black with lateral blotches, and 5th + 6th supralabials in contact with the parietal (temporals 0 + 0). Apostolepis albicollaris inhabits interfluvial savannas and appears to be the most abundant species of Apostolepis in the region of the type-locality, located within the core area of the Cerrado domain of Central Brazil. Detected patterns of character state distribution supports the inclusion of A. albicollaris in a distinct intrageneric assemblage, here named the dimidiata species-group, an inferred clade diagnosed by the following putative synapomorphies: prominent (to strongly pointed) rostral; slightly rounded terminal shield; snout mostly black with small (to indistinct) light spots; upper lip extensively white; and, in most species, absence of nuchal collars. Although superficially closest to A. dimidiata, no putative synapomorphy was found to support a sister-group relationship between these species. Instead, A. albicollaris seems to have retained putatively plesiomorphic features suggestive of an ancient divergence relative to other members of the dimidiata species group.