Integrative systematics of the taxonomically complex gobiid genus Glossogobius Gill, 1859 (Teleostei: Gobiidae) from the south-western Indian Ocean, with a description of a new species

Abstract Glossogobius, a species-rich gobiid genus with 42 recognized species distributed in the Indo-West Pacific, lacks a comprehensive phylogenetic analysis. The highest diversity of the genus occurs in the tropical West Pacific, highlighting this region as a centre of endemism. In contrast, the Indian Ocean has lower diversity (nine species). This study offers the first thorough description of Glossogobius diversity in the south-western Indian Ocean through integrative analyses. Our findings reveal nine lineages, five of which are newly identified, including a new species, Glossogobius hanisii sp. nov., described from southern Africa and Madagascar. Seven species/lineages, along with G. kokius from Mauritius and G. tenuiformis, are endemic to the south-western Indian Ocean. With 65% of Indian Ocean Glossogobius species/lineages being endemic to the south-western region, it is identified as a hotspot of endemism. The genetic structuring of these lineages along the east coast of southern Africa appears to be shaped by an interplay between life history, oceanographic conditions, and adaptations to marine biogeographic regions. Additionally, our findings highlight Madagascar’s central role in Glossogobius diversification and evolution of unique gobies, provide a framework for a comprehensive revision of Glossogobius in the region, and facilitate the identification of conservation units and the formulation of management measures.