A Miocene pearleye, Benthalbella praecessor, sp. nov. (Teleostei, Aulopiformes), from Sakhalin Island, Russia: the first known skeletal record for the family Scopelarchidae

Fishes of the family Scopelarchidae, commonly known as pearleyes, are basal alepisauroids that occur worldwide at depths between 300 and 1,000 m. A new pearleye species, Benthalbella praecessor, sp. nov., is described from the middle Miocene (late Langhian-early Serravallian; 14.6-13.1Ma) deposits of the Kurasi Formation, Sakhalin Island, Russia, based on 24 well-preserved specimens. These specimens consist primarily of articulated skeletons and represent the first fossil skeletal remains for the family Scopelarchidae. Benthalbella praecessor appears to be closely related to the extant B. dentata and is characterized by a unique combination of morphological and meristic features, including 54-56 vertebrae, dorsal fin with 8-9 rays, anal fin with about 19-22 rays, very short pectoral fin containing 26-28 rays, elongate pelvic fin, enlarged second infraorbital, subopercle larger than the opercle, and urohyal with a posterodorsally directed hook-like process along its anterodorsal margin. Paleoecological considerations suggest that Benthalbella praecessor was a deep-sea fish that inhabited the cold-temperate waters of the northwestern Pacific about 14Ma.