A reconsideration of the systematic status of Rhoptropus bradfieldi diporus Haacke 1965

Abstract

We re‐evaluated the taxonomic status of Rhoptropus bradfieldi diporus, an endemic Namibian gecko. Preanal pores, the character originally used to diagnose the taxon, are variably present, but R. b. diporus is reliably differentiated from R. b. bradfieldi by smaller, more rounded scalation of the thigh and precloacal regions. The two forms are also distinguished by relatively high levels of sequence divergence (9.7–11.6%) observed for the mitochondrial cytochrome b gene. On the basis of these distinct morphological and molecular characteristics, we regard R. diporus as a valid species restricted to the Brandberg and areas north of the Ugab River. The significance of consistent colour differences between R. diporus and R. bradfieldi remains unclear, but the melanism prevalent in the latter species may be an adaptation to the cool coastal Namib fog belt. Morphological variation in R. bradfieldi is also evident in the southern portion of its range, where inland and coastal populations are notably distinct. The precise geographic patterns of this variation (and its possible evolutionary significance) warrant further investigation.