Molecular data in conjunction with morphology help resolve the Hemidactylus brookii complex (Squamata: Gekkonidae)

Abstract

Molecular data are increasingly being used to resolve cryptic species complexes; however, subsequent formal species description and taxonomic revisions often remain incomplete. Given that most species are described based on morphology-based alpha taxonomy, one cannot resolve nomenclatural issues of species complexes without the aid of morphology. In this study, we examined the taxonomic status of a long-known human commensal and species complex, Hemidactylus brookii. To this end, samples of H. cf. brookii and related species were collected across India. We analyzed molecular as well as morphological data to resolve the taxonomy of this species complex. Seven deeply divergent, well-supported clades were recovered using the mitochondrial phylogeny, five of which were also retrieved in the nuclear tree. One of these consists of five morphologically distinct species of ground-dwelling Hemidactylus. The genetic distances across each clade of putative species of H. brookii sensu lato were comparable to that between morphologically distinct species of ground-dwelling Hemidactylus. Meristic characters such as number of precloacal-femoral pores, number of non-pore bearing scales interrupting the series of pored scales, dorsal pholidosis, and presence/absence of divided lamellae can be used to distinguish these putative species from each other. However, morphological characters of H. brookii sensu stricto did not correspond to any of the putative species studied. The study also revealed that the ``H. brookii complex'' in India includes two commensal species, Hemidactylus parvimaculatus and Hemidactylus murrayi. Furthermore, these two lineages have independently acquired adaptations that could have assisted them in exploiting human habitat. An identification key to diagnose species within this complex and rest of the Hemidactylus in India is proposed.