Revision of the genus Lepidopsetta Gill, 1862 (Teleostei: Pleuronectidae) based on larval and adult morphology, with a description of a new species from the North Pacific Ocean and Bering Sea

The fl atfi shes (Pleuronectiformes) of the eastern North Pacifi c Ocean constitute a major component of the commercial fi sheries of the region. In the Bering Sea, which encompasses the largest fi sheries resource of the United States, the rock soles of the genus Lepidopsetta are the second most abundant fl atfi shes and the third most abundant commercial groundfi sh species, second only to yellowfi n sole (Limanda aspera) and walleye pollock (Theragra chalcogramma) (NMFS, 1999). At the species level, eastern North Pacifi c pleuronectids have been considered well known. Nearly all species were recognized and described during the latter half of the 1800s, primarily through the activities of California ichthyologists. Among the names that remain valid, the last species to be described was Limanda sahkalinensis Hubbs, 1915, although in the western Pacifi c Microstomus shuntovi Borets, 1983, was most recently described from the northwestern Hawaiian ridge. However, these earlier works were based on adult morphology, and only recently has a knowledge of the ontogeny of these species been acquired. Among the descriptions of early life history stages of eastern North Pacifi c pleuronectids, one morphological form could not be traced to a recognized species. Examination of this form led to the following revision of the genus Lepidopsetta. Four nominal species have been described and allocated to the genus Lepidopsetta: Platessa bilineata Ayres, 1855a, was described from San Francisco material, and apparently without the knowledge of Ayres’ slightly earlier description, a specimen collected near Puget Sound was described as Platichthys umbrosus Girard, 1856. Gill (1862) erected Lepidopsetta to contain Platichthys umbrosus and later (1864) indicated that Platessa bilineata Ayres, 1855a, was allied and perhaps congeneric. Lockington (1879b) published a redescription of L. umbrosa, describing the misidentifi ed new species Isopsetta isolepis (Lockington, 1880a), which he ultimately removed from Lepidopsetta to his new genus Isopsetta (Lockington, 1883). In his description of Lepidopsetta isolepis, he treated Platichthys umbrosus Girard as a synonym of L. bilineata. Nearly 20 years after Gill’s erection of Lepidopsetta, Cope (1873) described Pleuronectes perarcuatus from Alaska, later considered a synonym of L. bilineata by Jordan and Gilbert (1881). Jordan and Evermann (1898) considered each of these nominal species members of Lepidopsetta and further as synonyms of L. bilineata, although they recognized the northern populations (“Puget Sound and northward”) as L. bilineata umbrosa. Finally, Japanese Lepidopsetta were described by Snyder (1911) as L. mochigarei and Jordan and Hubbs (1925) considered all Japanese Lepidopsetta to be representatives of this species. More recently, the genus has been envisioned as containing either two speRevision of the genus Lepidopsetta Gill, 1862 (Teleostei: Pleuronectidae) based on larval and adult morphology, with a description of a new species from the North Pacifi c Ocean and Bering Sea