Schliewen, U.,  Schwarzer, J.,  Wedekind, J.,  Alibert, P.,  Dunz, A.,  Vreven, E. & Ifuta, S. 2013. ‘Steatocranus: towards an integrative view on the systematics and taxonomy of a complex miniature species flock of rheophilic cichlids’. Fifth International Conference of the Pan African Fish and Fisheries Association (PAFFA5). Book of abstracts.

Conference abstract

The rheophilic genus Steatocranus Boulenger, 1899 (Cichlidae: Pseudocrenilabrinae: Steatocranini) currently comprises nine valid species distributed in rapids of the Central and Lower Congo basin and in the Volta Basin. Molecular phylogenetic analyses based on mitochondrial, and nuclear DNA sequences as well as on anonymous multilocus DNA fragment analyses (AFLPs) in combination with digital and classic morphometric analyses revealed the existence of at least 19 diagnosable Steatocranus-lineages in the Lower Congo, which are currently being described or redescribed as species-level taxa. The Volta-River species “Steatocranus” irvinei is not closely related to the Congo-Steatocranus, but is related to a West African haplotilapiine tribe Gobiocichlini, and consequently will be transferred to a new genus. A subgroup of the true Steatocranus has formed an eco-morphologically diverse miniature species flock along the Lower Congo rapids. Explicit tests for ancient reticulations based on AFLP multilocus data strongly suggest, that at least one taxon of the Lower Congo, S. glaber, is of hybrid origin, and that multiple additional reticulations have taken place in the course of cladogenesis of Steatocranus. The extent of reticulations in the phylogeny of Steatocranus, as well as in other rheophilic cichlid taxa at the base of the East African cichlid radiations has manifold implications not only for the potential hybrid origin of the cichlid radiations but also for the monophyly criterion as the conceptual basis for the description of higher cichlid taxa.