Goatfishes (Teleostei: Mullidae) of the Socotra Archipelago: Diversity and distributional biogeography, with a new record of Parupeneus heptacantha (Lacépède, 1802)

The diversity of goatfishes from the Socotra Archipelago is documented for the first time. The distributional biogeography of the family in the Arabian region is analyzed and thoroughly discussed in the context of the western Indian Ocean. Twelve species of two genera, Mulloidichthys and Parupeneus , are positively recorded, including a new record for Parupeneus heptacantha . Upeneus heemstra is visually recorded, pending further documentation. The Socotra Archipelago thus hosts 13 of the 31 species found in Arabia. This degree of species richness is comparable to other Arabian ecoregions. With a single species the richness of Upeneus stands out as very low. Biogeographically, three main Arabian units are identified: a “Red Sea unit”, a “Gulf unit”, and a “Socotra unit”. The former two units are strongly characterized by endemics, notably within Upeneus , while there are no species endemic to the latter. The “Socotra unit”, comprising the Socotra Archipelago, eastern Gulf of Aden, and southern Oman, resembles more strongly all sites of the western Indian Ocean than the Arabian sites. The “Gulf unit” is the most distant to all other sites. These units do not cluster to a discrete “pan-Arabian” region within the wider western Indian Ocean. The Mullidae thus strongly contrast overall biogeographic patterns of coastal fishes and reef-building corals, which cumulatively suggest that Arabia forms a discrete biogeographic unit within the Indian Ocean. The study serves further analyses of contrasting biogeographies of major coastal fish families in Arabia, with a focus on the role of the southern Arabian upwelling areas.