Mitochondrial DNA sequences (1137 bp) of the cytochrome b gene and craniodental and craniometric data were used to investigate the evolutionary relationships of six putative rodent taxa of Otomys (family Muridae: Subfamily Murinae: Tribe Otomyini) co-occurring in the Western Cape and Eastern Cape provinces of South Africa. Phylogenetic analysis of 20 new sequences together with craniodental and craniometric characters of 94 adult skulls reveal the existence of a unique lineage of Otomys cf. karoensis (named herein Otomys willani sp. nov.) from the Sneeuberg Centre of Floristic Endemism in the southern Drakensberg Mountain Range. Craniometric analysis distinguished O. karoensis from O. willani and identified a further four localities in the range of the latter species. We document southern range extensions of both Sloggett's ice rat, Otomys sloggetti, and the vlei rat Otomys auratus to the Sneeuberg Mountain Range, in addition to appreciable genetic divergence between Sneeuberg and southern and central Drakensberg populations of O. sloggetti. Our results demonstrate parallel patterns of cryptic speciation in two co-occurring species complexes (Otomys irroratus s.l. and O. karoensis s.l.) associated closely with the boundaries of biomes (fynbos vs. grassland biomes) and geological formations (Cape Fold Belt vs. Great Escarpment).
Bibliographical noteFunding Information:
The samples used for this study were collected by Armand Kok and Dr S. Maree. P.J.T. acknowledges the financial support by the University of Venda, the South African National Research Foundation and the Department of Science and Technology under the South African Research Chair Initiative (SARChI) on Biodiversity Value and Change within the Vhembe Biosphere Reserve hosted at the University of Venda and co-hosted by the Centre for Invasion Biology at University of Stellenbosch (NRF grant unique number GUN 87311). N.P.B., G.C. and C.M.R.K. thank Rhodes University Botany Department for the facilities and equipment provided during the course of this study. Sequencing was conducted using facilities at Rhodes University Department of Biochemistry, Microbiology and Biotechnology. Funding for this research was provided by the National Research Foundation of South Africa (grant unique number GUN 2069059 to N.P.B.). We thanks two anonymous reviewers for their helpful comments on an earlier draft of this manuscript.
© 2019 The Linnean Society of London, Zoological Journal of the Linnean Society.