Dicynodontoides kubwa, sp. nov. (Synapsida: Anomodontia), a new large emydopoid from the base of the Usili Formation (Ruhuhu Basin, Tanzania)

Approximately 40% of the vertebrate species recorded from the upper Permian Usili Formation of Tanzania are dicynodonts. Among these are several members of Emydopoidea, a clade of small- to medium-sized dicynodonts notable for their high morphological disparity. Here, we describe Dicynodontoides kubwa, sp. nov. as a new species of emydopoid from the basal conglomerate of the Usili Formation. This horizon contains endemic taxa and taxa very rare in Africa, including the enigmatic temnospondyl Peltobatrachus, the burnetiamorph Pembecephalus, and the giant gorgonopsian Inostrancevia. Like other emydopoids, the anterior dentary of Dicynodontoides kubwa is shovel-shaped and the humerus bears an ectepicondylar foramen. Within Emydopoidea, we refer this material to Dicynodontoides due to its wide lateral dentary shelf with a deep dorsal depression, lack of both dentary table and posterior dentary sulcus, and a plate-like outgrowth on the distal shaft of the fibula. Dicynodontoides kubwa is distinguished from its congeners primarily by size: all elements are at least twice as large as those of D. nowacki, making it the largest emydopoid to date. Other clear distinctions between D. kubwa and both D. nowacki and D. recurvidens include perpendicular grooves on the lateral edges of the anterior dentary and a more laterally curved ilium that has a thicker, more rounded anterior end. The recognition of a new species of Dicynodontoides adds to the complexity of the basal conglomerate tetrapod assemblage, especially how its dicynodont component relates to dicynodont diversity higher in the Usili section.