Plataplochilus Eliasi (cyprinodontiformes: Procatopodidae) a New Species from the Upper Noumbi River in the Republic of the Congo

Forty years after the last Plataplochilus description was published, a new species, P. eliasi, is described from streams in the upper reaches of the Bondo River tributary (Noumbi Basin) in the Mayumbe Mountains of the Republic of the Congo. The new species is distinguished from all congeners by the males' colouration pattern, which consists of a crescent-shaped dark blue band on the lower half of the body, and the larger body depth (38.4-42.4% of standard length - SL). All other described species of which the colour pattern in life specimens is known are lacking this band and have a silvery lower body with (depending on the species) a light blueish, greenish or brownish iridescence. In addition, Plataplochilus miltotaenia and P. pulcher have a narrow mid-longitudinal red line on the flanks that is absent in all other described species, including P. eliasi sp. nov. The body depth (presented as a percentage of SL) is also useful in distinguishing the new species (body depth 38.4-42.4% of SL) from its congeners: P. cabindae (25.3-27.8% of SL) P. chalcopyrus (23.3-27.0% of SL), P. micrurus (25.5% of SL in the single type), P. mimus (29.7-32.5% of SL), P. ngaensis (28.4-31.5% of SL), P. pulcher (27.4-33.5% of SL), P. terveri (28.7-30.9% of SL) and P. loemensis (30.7-33% of SL). The taxonomic status of the genus is discussed, and for the first time osteology of the genus is examined, revealing the following likely diagnostic characters shared by all examined species: anterior portion of alveolar arm of premaxilla developed in a squared process, rectangular and anteroposteriorly elongated lachrymal, dorsoposterior process of autopalatine directed upwards, elliptical supracleithrum, and dorsoposterior border of cleithrum broad and posteriorly elongated. Detailed habitat, ecological and distribution data for this new species are also provided.