The red-billed hornbill (Tockus erythrorhynchus) is the most studied hornbill in Africa (Kemp and Kemp, in press). It has been the subject of four postgraduate theses from across its entire range (Kemp, 1976; Wambuguh, 1987; Diop, 1993; Delport, 2001) that included all three subspecies then recognized in systematic revisions of the species (Sanft, 1960; Kemp and Crowe, 1985; Fry et al., 1988; Kemp, 1995). These were the nominate T. e. erythrorhynchus (Temminck, 1823), across the savannas of western, northern and eastern sub-Saharan Africa, T. e. rufirostris (Sundevall, 1850), on the savannas of southern Africa, and T. e. damarensis (Shelley, 1888), on the more arid savannas of southwestern Africa. Keywords: Bucerotidae, Tockus erythrorhynchus, T. e. ruahae, Subspecies, Tanzania, New Subspecies.