A taxonomic revision of the south-eastern dragon lizards of the Smaug warreni (Boulenger) species complex in southern Africa, with the description of a new species (Squamata: Cordylidae)

A recent multilocus molecular phylogeny of the large dragon lizards of the genus Smaug Stanley et al. (2011) recovered a south-eastern clade of two relatively lightly-armoured, geographically-proximate species (Smaug warreni (Boulenger, 1908) and S. barbertonensis (Van Dam, 1921)). Unexpectedly, S. barbertonensis was found to be paraphyletic, with individuals sampled from northern Eswatini (formerly Swaziland) being more closely related to S. warreni than to S. barbertonensis from the type locality of Barberton in Mpumalanga Province, South Africa. Examination of voucher specimens used for the molecular analysis, as well as most other available museum material of the three lineages, indicated that the ‘Eswatini’ lineage—including populations in a small area on the northern Eswatini–Mpumalanga border, and northern KwaZulu–Natal Province in South Africa—was readily distinguishable from S. barbertonensis sensu stricto (and S. warreni) by its unique dorsal, lateral and ventral colour patterns. In order to further assess the taxonomic status of the three populations, a detailed morphological analysis was conducted. Multivariate analyses of scale counts and body dimensions indicated that the ‘Eswatini’ lineage and S. warreni were most similar. In particular, S. barbertonensis differed from the other two lineages by its generally lower numbers of transverse rows of dorsal scales, and a relatively wider head. High resolution Computed Tomography also revealed differences in cranial osteology between specimens from the three lineages. The ‘Eswatini’ lineage is described here as a new species, Smaug swazicus sp. nov., representing the ninth known species of dragon lizard. The new species appears to be near-endemic to Eswatini, with about 90% of its range located there. Our study indicates that S. barbertonensis sensu stricto is therefore a South African endemic restricted to an altitudinal band of about 300 m in the Barberton–Nelspruit–Khandizwe area of eastern Mpumalanga Province, while S. warreni is endemic to the narrow Lebombo Mountain range of South Africa, Eswatini and Mozambique. We present a detailed distribution map for the three species, and a revised diagnostic key to the genus Smaug.