A new goatfish, Upeneus seychellensis sp. nov. (Mullidae), from the Seychelles Bank, with remarks on Upeneus guttatus and a key to Western Indian Ocean Upeneus species

Abstract

The mullid genus Upeneus is highly diverse, with a considerable number of new species found only recently. Based on 16 specimens of Upeneus collected at the southeastern edge of the Seychelles Bank, a large oceanic platform in the Western Indian Ocean, a new species, Upeneus seychellensis, is described. Comparisons with and among populations of the closely related U. guttatus are made. By integration of an extensive, comparative data set consisting of 50 morphometric and meristic and several colour characters obtained from 25 additional Upeneus species, an updated key for the 18 Western Indian Ocean species is provided. The new species can be distinguished from all other congeners of the japonicus-species group, a complex of species with seven dorsal-fin spines, by a combination of number of pectoral fin rays and gill rakers, body depth at anal fin origin, caudal peduncle depth, anal fin size, first dorsal-fin height and colour of the lower caudal-fin lobe. Co-occurring specimens of U. guttatus are considerably differentiated in morphology and colour from other Indian Ocean populations and this was also found for a single specimen from the Gulf of Suez. These results indicate isolation and the formation of local adaptation in more remote areas of the Indian Ocean, but the influence of phenotypic plasticity also needs to be considered.