A new genus and species of gnathiid isopod, Afrignathia multicavea gen. et sp. n., is described from material collected during the 1960s and 1970s in False Bay, offshore between Still Bay and Mossel Bay, and off Cape Point. This gnathiid does not conform to any other known species, having morphological characteristics not seen in the other 11 recognized genera. Features making the genus unique include a pylopod consisting of only one article, a mandible with two rows of unequal teeth on the blade and apex, and cephalosome appendages that could be maxillae 1 (maxillules), which are usually absent in all known male gnathiids. This species is also characterized by clusters of sensory pits scattered over the cephalosome and pereon.