Giants in a minute catfish genus: first description of fossil Mochokus (Siluriformes, Mochokidae) in the Late Miocene of Chad, including M. Gigas, sp. nov.

The first Mochokus (Siluriformes, Mochokidae) remains of the fossil record are described, including a new species based on a sub-complete neurocranium discovered in the Late Miocene deposits of Toros-Menalla, Chad, Central Africa, dated to 7.0 Ma. Mochokus gigas, sp. nov., is the first fossil species described for the family Mochokidae, which is the largest family of African catfishes. The description is based on the comparison with the two living species of the genus, M. niloticus and M. brevis. Mochokus gigas, sp. nov., is a very large species presenting original features, notably on the pectoral spines and on the anterior part of the neurocranium. One of the apomorphies characterizing the modern genus Mochokus is found on the fossil: the root of the mesocoracoid arch is located on the posterior side of the vertical lamina of the coracoid and lacks any dorsally directed prominence. Several other Mochokus fossil remains, including nuchal plates, cleithra, and dorsal spines, are described and attributed to Mochokus, sp. indet., or Mochokus sp. Finally, and on the basis of preliminary observations of the fossil fish assemblages from different sites of Toros-Menalla, the lack of Mochokus fossil remains is discussed.