Identification of enigmatic Mediterranean fish Gobius ater Bellotti, 1888 (Teleostei: Gobiidae) based on morphology from underwater photographs.

Gobius ater Bellotti, 1888 is the Mediterranean gobiid species whose live appearance has remained unknown the longest since its description. A goby observed in southern France in 2021 is here identified as G. ater based on a diagnosis of morphological characters visible on high-quality underwater photographs. Then, the authors provide the first description of colouration in live G. ater and a species diagnosis based on colouration. This diagnosis allows the authors to validate a previous photographic record, also from France. Reviewing all claims of G. ater, they argue that only seven records are unambiguously valid, including the two photographic records presented here.