Crassabwa Lugo-Ortiz & McCafferty (Ephemeroptera : Baetidae), n. gen., is erected for a small monophyletic group of distinctive Afrotropical species previously assigned to Afroptilum Gillies and Centroptilum Eaton, including C. badia (Kopelke), n. comb., C. flava (Crass), n. comb. (type species), C. loweae (Kimmins), n. comb., and C. vitrea (Navás), n. comb. Larvae of Crassabwa are distinguished by possessing a thumb-like distomedial process on labial palp segment 2, a proximal arc of setae on the tibiae, two enlarged subapical denticles in the tarsal claws, and seven gill pairs with posteriorly oriented tracheae and anterodistal marginal serration. Adults are distinguished by possessing hindwings with two longitudinal veins and an elongate, acute costal process, and a robust segment 3 of the male genital forceps. The larval stage of C. flava is redescribed, and new figures are provided to illustrate previously overlooked characters.