The first Paleozoic temnospondyl from Zambia: a new species of Rhineceps from the Permian Madumabisa Mudstone Formation, Mid-Zambezi Basin

The Permian temnospondyl fossil record of South Africa’s Karoo Basin is well known but preserves a relatively low abundance and low diversity assemblage composed exclusively of rhinesuchids (viz., Lacosaurus, Rhinesuchoides, Rhinesuchus, and Uranocentrodon). Elsewhere in southern Pangea, temnospondyl taxonomic diversity is even lower, with coeval deposits yielding endemic forms such as Rhineceps nyasaensis from the Chiweta Beds of Malawi and Peltobatrachus pustulatus from the Usili Formation of Tanzania. Permian rocks are present in both the Mid-Zambezi and Luangwa basins of Zambia, but neither has yielded diagnostic temnospondyl fossils so far. Here we describe two nearly complete temnospondyl skulls from the lower portion of the upper Madumabisa Mudstone Formation of southern Zambia’s Mid-Zambezi Basin. These medium-sized skulls both show a subtriangular general outline with a well-developed snout, relatively large orbits, very posterolaterally extended tabulars, a small internarial opening on the dorsal surface of the snout, and a large, heart-shaped anteropalatal depression. We refer these specimens to a new species of rhinesuchid, Rhineceps karibaensis, sp. nov., which enlarges the geographic and stratigraphic range of the genus. The results of an updated cladistic analysis suggest that Rhineceps karibaensis, sp. nov. is the sister taxon of Rhineceps nyasaensis from Malawi. Our recognition of a rhinesuchid in southern Zambia increases the diversity of the amphibian fauna in southern Pangea prior to the end-Permian mass extinction and confirms the broad distribution of rhinesuchids across the region.