Revision of the Chromidotilapia batesii/finleyi-complex with description of a new genus and three new species
Summary: The cichlid species Chromidotilapia batesii and C. finleyi differ from other Chromidotilapia species in the combination of the following characters: four openings of the laterosensory system in the lacrimal bone, three infraorbital bones, sexual dimorphism not or hardly developed, a black spot in the soft part of the dorsal fin visible in all juveniles and some adults. Therefore, the new genus Benitochromis is erected for these two species, with the type species Benitochromis finleyi (Trewavas, 1974). Further species are B. batesii (Boulenger, 1901), B. riomuniensis (Linke & Staeck, 1981) and the three new species B. conjunctus spec. nov., B. nigrodorsalis spec. nov., and B. ufermanni spec. nov. With the exception of B. batesii all species of the genus are pair bounding ovophilic mouthbrooders with a spawning behaviour similar to substrate spawning cichlids. Benitochromis batesii is a larvophilic mouthbrooder which always spawns in caves. In B. ufermanni only females are brooding. In all other species both sexes are mouthbrooding. Furthermore, the species differ from each other in a combination of various metric and meristic characters, in colouration and in patterns. Only B. batesii and B. ufermanni have vertical bars on the body. Compared to B. batesii, B. ufermanni shows a high degree of sexual dichromatism and males have dark spots on the whole caudal fin. In contrast to all other species, B. conjunctus possesses conjugating horizontal stripes on the body. B. nigrodorsalis has black colouration in the dorsal fin and B. finleyi is characterized by an iridescent blue coloration on cheeks, operculum and anterior part of the body. Benitochromis conjunctus is known only from West Cameroon; here it lives in tributaries (rivers and creeks) of the middle part of the Mungo River and in creeks east of Mount Cameroon. Benitochromis nigrodorsalis is found in north-western parts of Cameroon, near the coast as well as in the west of Mount Cameroon. Thus, this species occurs west and south-west of the distribution of B. conjunctus. Benitochromis ufermanni seems to be endemic in a small region in and around the Korup National Park in Cameroon. Nanochromis riomuniensis Linke & Staeck, 1981 possesses the typical characters of Benitochromis and is therefore defined as the sixth species of this genus. It is suggested that specimens hitherto regarded as southern population of B. finleyi belong to B. riomuniensis, as metric and meristic data coincide and areas of distribution of both species are continuous.