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.

This article focuses on the taxonomic diversity, phylogenetics, and biogeography of the gobiid fish genus Glossogobius in the south-western Indian Ocean. Through integrative molecular and morphological analyses, the study identifies nine distinct lineages in the region, including five newly recognized lineages and the formal description of a new species, Glossogobius hanisii sp. nov., distributed across southern Africa and Madagascar. The research highlights the south-western Indian Ocean as a significant hotspot of Glossogobius endemism, with 65% of Indian Ocean species/lineages endemic to this area, and underscores Madagascar's central role in the genus's diversification, particularly in subterranean habitats. The study also revises the taxonomy of key species complexes, clarifies phylogeographic patterns influenced by marine currents and biogeographic provinces, and provides a taxonomic key to distinguish Glossogobius species in Africa and Madagascar, thereby informing conservation strategies for these ecologically important fishes.