Repeated evolution of blanched coloration in a lizard across independent white-sand habitats.

The White Sands lizards of New Mexico are a rare and classic example of convergent evolution where three species have evolved blanched coloration on the white gypsum dunes. Until now, no geological replicate of the pattern had been described. However, one of the White Sands species, the lesser earless lizard (Holbrookia maculata), has been discovered to also inhabit the Salt Basin Dunes of Texas, where it has also evolved a blanched morph. We here present a first phenotypic and genetic description of the Salt Basin Dunes population of H. maculata. Phylogenetic inference based on a housekeeping gene (ND4) and a classic candidate gene in the melanin-synthesis pathway (Melanocortin 1 Receptor; Mc1r) shows the newly discovered population as an independent lineage, with no evidence of genetic parallelism in the coding region of Mc1r. Initial morphological data suggest that while this population displays convergent evolution in blanched coloration, there are divergent patterns in limb length and habitat use behavior between the gypsum environments. Our findings present the White Sands/Salt Basin Dunes as an exceptionally promising comparative model for studies of adaptation and convergent evolution.

Phylogenetic structure of Holbrookia lacerata (Cope 1880) (Squamata: Phrynosomatidae): one species or two?

Species delimitation attempts to match species-level taxonomy with actual evolutionary lineages. Such taxonomic conclusions are typically, but not always, based on patterns of congruence across multiple data sources and methods of analyses. Here, we use this pluralistic approach to species delimitation to help resolve uncertainty in species boundaries of phrynosomatid sand lizards of the genus Holbrookia. Specifically, the Spot-tailed Earless Lizard (H. lacerata) was historically divided into a northern (H. l. lacerata) and southern (H. l. subcaudalis) subspecies based on differences in morphology and allopatry, but no research has been conducted evaluating genetic differences between these taxa. In this study, patterns in sequence data derived from two genes, one nuclear and one mitochondrial, for 66 individuals sampled across 18 counties in Texas revealed three strongly supported, reciprocally monophyletic lineages, each comprised of individuals from a single geographic region. Distinct genetic variation evident across two of these regions corresponds with differences in morphology, differences in environmental niche, and lines up with the presumed geographic barrier, the Balcones Escarpment, which is the historical subspecies boundary. The combined evidence from genetics, morphology and environmental niche is sufficient to consider these subspecies as distinct species with the lizards north of the Balcones Escarpment retaining the name Holbrookia lacerata, and those south of the Balcones Escarpment being designated as Holbrookia subcaudalis.

On Psilorhynchus sucatio and P. nudithoracicus, with the description of a new species of Psilorhynchus from northeastern India (Ostariophysi: Psilorhynchidae).

Psilorhynchus sucatio (Hamilton) is redescribed based on the examination of 462 specimens, 13-67 mm standard length (SL). Psilorhynchus nudithoracicus Tilak & Husain is redescribed based on the examination of 97 specimens, 10-68 mm SL. Psilorhynchus gracilis Rainboth is placed in the synonymy of P nudithoracicus. Psilorhynchus hamiltoni, a new species and a member of the P. balitora species group, is described from the Tista River in West Bengal, India. It is distinguished from all other members of the P. balitora species group by having a well-developed lateral stripe, 6-7 poorly developed saddles that do not make contact with the lateral blotches, 7-11 lateral blotches, 34-35 lateral line scales, 9+8-9 principal caudal-fin rays, 36 total vertebrae, and the ventral surface between paired fins with a broad rectangular scaleless patch. A key to the species groups of Psilorhynchus is also provided, as are revised diagnoses for the P. balitora and P. nudithoracicus species groups.