Two new species of Acontias (Acontinae, Scincidae) from the Mpumalanga Highveld escarpment of South Africa

Abstract

The African genus of fossorial legless lizards (Acontias Cuvier) currently comprises 26 species and subspecies. In a recent study on the two disjunct populations of Acontias breviceps Essex, the presence of cryptic species was discovered. Here, we increase the sampling size and describe these disjunct populations from the Mpumalanga Escarpment of South Africa as new species. The new species differ from congeners based on a combination of factors, including the number of midbody, ventral, and subcaudal scale counts, ventral pigmentation, allopatric distributions, and genetic divergences. The new species are genetically distant from nominal A. breviceps, with which it shares overall pigmentation and scalation. The new description adds to the growing number of Mpumalanga escarpment endemic reptiles, and highlights the area as a biodiversity hotspot. The use of vertebral counts as a distinguishing character between species is briefly discussed.

Unexpected phylogenetic relationships within the world's largest limbless skink species ( Acontias plumbeus ) highlight the need for a review of the taxonomic status of Acontias poecilus

“…However, this is not entirely unexpected, since Lamb et al. () already found a 5.3% divergence in the Cytb sequences between two A. plumbeus samples, which is even lower than those we found in this study (5.6%–6.7%, see Table ), but higher than 3.5 ± 0.7% found between A. albigularis and A. gracilicauda (Conradie et al., ). More importantly, a divergence between 2.3% and 2.8% for the 16S (Table ) represents a higher value than the average intraspecific sequence divergence in Acontias (<2%) found by Daniels et al.…”

“…Available DNA sequences of A. poecilus from a previous study (Lamb et al., ) were downloaded from GenBank. We also included one available sample each of A. gracilicauda (this study), A. wakkerstroomensis, and A. meleagris (both from GenBank) as outgroups, based on the currently accepted phylogeny for the subfamily Acontinae (Conradie et al., ; Lamb et al., ).…”

“…Museum numbers (ID number) are shown when applicable. References: (A) Daniels et al., ; (B) Daniels et al., ; (C) Lamb et al., ; (D) Conradie et al., .…”

“…Consequently, it has traditionally been considered a monotypic species with no substantial genetic and morphological variation among populations (Bates et al., ; Daniels et al., ), the only exception being the split between A. poecilus and A. plumbeus (Bourquin & Lambiris, ), with the former being initially considered a dwarf subspecies of the latter. After this taxonomic change, however, the hypothetical homogeneity within A. plumbeus contrasts with high levels of genetic diversity found in other Acontias taxa, such as the A. meleagris complex (Daniels et al., , ; Engelbrecht et al., ) or the A. gracilicauda/breviceps complex (Busschau et al., ; Conradie et al., ). Interestingly, phylogenetic research on the Acontinae has demonstrated close affinities among A. plumbeus , A. poecilus , A. breviceps, and A. gracilicauda (Daniels et al., , ; Engelbrecht et al., ; Lamb et al., ; Pyron et al., ).…”

“…This specialized group of fossorial skinks shows only traces of the pelvic girdle and a divided frontal bone in the skull (Broadley & Greer, ; Essex, , ). Two genera, Acontias and Typhlosaurus , are currently recognized within Acontinae (Branch & Bauer, ; Conradie, Busschau, & Edwards, ; Hedges, ; Lamb, Biswas, & Bauer, ), with the majority of the species being endemic to southern Africa (Branch, ), a fact that contributes to considering the subcontinent as one of the most species‐rich areas on the globe (De Villiers et al., ). However, some of the relationships among the Acontinae remain unclear, especially within Acontias (Bates et al., ), with the current number of species still increasing (Conradie et al., ).…”