Two New Species of Suckermouth Catfishes, Genus Chiloglanis (Siluriformes: Mochokidae), from Rapids of the Congo River

Two new species of Chiloglanis are described from widely separated rapids along the Congo River. Chiloglanis kinsuka, new species, is described from the lower Congo River and tributaries in the region of the Kinsuka rapids below Pool Malebo. Chiloglanis wagenia, new species, is described from the Wagenia Falls at Kisangani, more than 1600 kilometers upstream. Both species are easily distinguished from all described congeners, and from each other, by a large number of functional mandibular teeth arranged in a transverse straight line (40–67, mean 58 ± 7 in C. kinsuka; 38–42, mean 40 ± 2 in C. wagenia), and by the presence of elongate, fingerlike fimbriae emanating from the ventral and posterior surfaces of the paired premaxillae and extending into the oral cavity. Chiloglanis kinsuka is also readily distinguished from all congeners, including C. wagenia, by high numbers of primary premaxillary teeth (299–551; only 140–199 in C. wagenia), and by its being cryptophthalmic and largely depigmented with pallid pinkish skin without discernible patterning. Chiloglanis kinsuka is the first example of a cryptophthalmic and depigmented species within the Mochokidae. Chiloglanis kinsuka and C. wagenia are further distinguished from each other by the modal number of branchiostegal rays (modally five in C. kinsuka vs. modally six in C. wagenia), by the total number of anal-fin rays (typically 11 or more in C. kinsuka vs. never more than 10 in C. wagenia), and by the shape of the lateral ethmoid and its position in the bony orbit (free posterior margin absent, not forming part of bony orbit in C. kinsuka vs. free posterior margin present, forming part of the bony orbit in C. wagenia). Morphological characters useful in diagnosing the genus Chiloglanis and others supporting the close relationship of the two species described herein are discussed.