Phylogeny and Systematic Revision of the Gecko Genus Hemidactylus from the Horn of Africa (Squamata: Gekkonidae)

Abstract

The Horn of Africa supports a unique and rich diversity of squamate reptiles. Among them, the gecko genus Hemidactylus stands out as the most species-rich genus of the region. In this study, we assembled a genetic and morphological data set of 22 Hemidactylus species that form a clade termed the African radiation, which is part of the arid clade of the genus. We reconstructed their phylogenetic relationships using both concatenation-based approaches and species tree inference. Hemidactylus laevis, H. ophiolepoides, and H. somalicus have been sequenced and placed in a phylogenetic context for the first time in this study. Our results confirm the phylogenetic placement of these species within the African radiation of the genus. Early diversification within the clade, however, remains obscure. According to the analysis of concatenated data, H. laevis is sister to the rest of the clade, whereas the species tree analyses inferred the African radiation to be formed by two subclades, northern and southern, and H. laevis belonging to the former. We integrate evidence from multiple sources including genetic differentiation at both mitochondrial and nuclear levels, morphological disparification, and coalescent-based species delimitation to support the existence of two new species of Hemidactylus. We provide a formal description of these two new species, one from northern Ethiopia, Eritrea, and westernmost Somaliland, and one from southern Ethiopia, northern Kenya, and easternmost South Sudan. Furthermore, we found that of the morphological traits examined, the numbers of supralabials and infralabials bear phylogenetic signal and we were able to tentatively infer the phylogenetic placement of species for which genetic data are still missing.