Just off the Beach: Intrageneric Distinctiveness of the Bandtail Goatfishupeneus Taeniopterus(mullidae) Based on a Comprehensive Alpha-Taxonomy and Barcoding Approach

The phenotypic, distributional, and genetic distinctiveness of the bandtail goatfish Upeneus taeniopterus within the genus Upeneus (Mullidae) is elaborated using a comprehensive alphataxonomic and barcoding approach. Based on a large number of morphometric, meristic and colour characters obtained from 71 preserved or freshly photographed specimens, an updated diagnosis, a redescription, and detailed inter-and intraspecific comparisons are provided. The distribution information is revised with strong emphasis on ensuring correct species identification. Upeneus taeniopterus shows intraspecific variation in morphology and number of oblique bars on the caudal fin related to two size classes, 'subadults' (< 12 cm SL) and 'adults' (12 cm SL or larger). Indications for population differences were only detected for the smaller size class, possibly reflecting geographic developmental differences. This species is widely distributed in the Indo-Pacific from Mozambique to the Tuamoto Archipelago and from the Ryukyu Islands to Tonga and occurs mostly in very shallow subtidal sandy beach or lagoon habitats of oceanic islands and atolls. Four new records of the species for Palau, Papua (Indonesia), Tonga and Vanuatu are reported. Comparisons with all other 36 congeners revealed clear differences from U. taeniopterus in the combination of maximum size, eight meristic and colour characters, distributional range and habitat selection. The only congeneric species with similarly large maximum size and wide distributional range is Upeneus vittatus, which differs however in morphology, colour and habitat. The congeneric species differ from U. taeniopterus with sequence divergences which are comparable to those observed among genera. More genetic tissue samples are needed to further investigate the relatedness among Upeneus species and to search for phylogeographic patterns in U. taeniopterus. The need to thoroughly study the insufficiently explored subtidal sandy habitats of oceanic islands and atolls is emphasized.