Just out @ Journal of Vertebrate Paleontology
Tugenchromis pickfordi, gen. et sp. nov., from the upper Miocene—a stem-group cichlid of the ‘East African Radiation’
Melanie Altner, Ulrich K. Schliewen, Stefanie B. R. Penk & Bettina Reichenbacher
The highly diverse tropical freshwater fish family Cichlidae is sparsely represented in the fossil record. Here we describe the new cichlid †Tugenchromis pickfordi, gen. et sp. nov., from the Upper Miocene (9–10 Ma) of central Kenya. The new taxon possesses a unique combination of characters, including six lateral line foramina on the lacrimal, three lateral line segments, cycloid scales, and a low number of vertebrae (29), dorsal fin spines (13), and dorsal soft rays (9). Its lacrimal morphology and tripartite lateral line suggest an affinity with the present-day Lake Tanganyika tribes Ectodini and Limnochromini, and thus with members of the ‘East African Radiation’ among the African cichlids. To further elucidate the relationships of †T. pickfordi, we used a comprehensive comparative data set comprising meristic data from all present-day tribes of the ‘East African Radiation.’ Principal coordinates analyses support links between the fossil and Ectodini + Limnochromini, and additionally with modern Haplochromini. We conclude that †T. pickfordi could be an extinct lineage within the ‘most ancient Tanganyika tribes,’ or a stem lineage of the ‘ancient Tanganyika mouthbrooders.’ A direct relationship to the Haplochromini is unlikely because its members do not exhibit the derived characteristics of the lacrimal as seen in †T. pickfordi. Because Lake Tanganyika is located in the western branch of the East African Rift System, †T. pickfordi from the eastern branch supports the ‘melting-pot Tanganyika hypothesis,’ which posits that the cichlids of modern Lake Tanganyika are derived from riverine lineages that had already diversified prior to the lake formation.
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