Discovery of the freshwater genus Sicyopus (Teleostei: Gobioidei: Sicydiinae) in Madagascar, with a description of a new species and comments on regional dispersal

In the Indo-Pacific area, insular rivers are mainly colonized by gobiids of the Sicydiinae subfamily. These species spawn in freshwater, where the free embryos drift downstream to the sea before returning to rivers to reproduce; they are amphidromous. These gobies are the greatest contributors to the fish diversity and have the highest levels of endemism. Among the nine known genera of Sicydiinae, only two have been found in the West Indian Ocean, and only one (Sicyopterus) is known from Madagascar. Recently, two surveys discovered a new species in the genus Sicyopus. Sicyopus lord sp. nov. differs from other species by a combination of characters that includes a particular colour pattern, similar in both sexes; more scales than its congeners in lateral series (35-43), transverse back series (12-18) and a shorter caudal fin length in male fish. This paper describes the new species and discusses the presence of this genus in Madagascar.