Phylogeography and morphological variation of the northernmost distributed species of the Liolaemus lineomaculatus section (Liolaemini) from Patagonia

Lizards from the Liolaemus lineomaculatus section are endemic to Patagonia, southern South America. Three main groups are recognized within this section, one of which, the L. kingii group includes eleven species. The two northernmost distributed species of this group, L. somuncurae and L. uptoni, are endemic to a small area that partly overlaps with the Provincial Protected Area Somuncura Plateau (within the Somuncura massif). Knowledge available for these species is based on limited sample sizes, and mostly limited to their original descriptions; also a recent molecular phylogenetic study showed evidence for a closely related candidate species (Liolaemus sp. 4). In this paper we morphologically and genetically characterize the species L. somuncurae, L. uptoni, and L. sp. 4, and present past demographic hypotheses. We studied eighty lizards, and collected morphological and genetic data for almost all of them. The specific status of L. somuncurae and L. uptoni is supported by molecular, morphological, and distributional evidence, as well as the status of L. sp. 4; for which we recommend further morphological comparisons with other species of the L. kingii group. We also identified two novel lineages from restricted areas south of the Chubut River that we propose as candidate species. We extend previously published evidence (from plants and rodents) supporting the role of the Chubut River as an allopatric barrier. Also, in agreement with previous results based on plants, we found evidence for two refugia in northwestern Chubut, for which we encourage conservation efforts.