Molecular phylogeny and morphological revision of the Ctenotus labillardieri (Reptilia: Squamata: Scincidae) species group and a new species of immediate conservation concern in the southwestern Australian biodiversity hotspot

Abstract

Ctenotus is the largest and most diverse genus of skinks in Australia with at least 97 described species. We generated large mitochondrial and nuclear DNA data sets for 70 individuals representing all available species in the C. labillardieri speciesgroup to produce the first comprehensive phylogeny for this clade. The widespread C. labillardieri was sampled extensively to provide the first detailed phylogeographic data set for a reptile in the southwestern Australian biodiversity hotspot. We supplemented our molecular data with a comprehensive morphological dataset for the entire group, and together these data are used to revise the group and describe a new species. The morphologically highly variable species C. labillardieri comprises seven well-supported genetic clades that each occupy distinct geographic regions. The phylogeographic patterns observed in this taxon are consistent with studies of frogs, plants and invertebrates, adding strength to emerging biogeographic hypotheses in this iconic region. The species C. catenifer, C. youngsoni, and C. gemmula are well supported, and despite limited sampling both C. catenifer and C. gemmula show substantial genetic structure. The threatened C. lancelini from Lancelin Island and the adjacent mainland is the sister taxon to a new species from the Swan Coastal Plain, which we describe as C. ora sp. nov. This species is a habitat specialist, occurring primarily in sandy regions south of Perth that currently are under intense development. Ctenotus ora sp. nov. should be considered for conservation attention immediately.