540 



Fishery Bulletin 98(3) 



cies, L. bilineata of the eastern North Pacific Ocean and 

 Bering Sea and L. mochigarei of the western North Pacific 

 around Japan (Hubbs, 1915; Sakamoto, 1984b), or a single 

 species, L. bilineata, with two subspecies L. b. bilineata 

 and L. b. mochigarei in the Bering Sea and western Pacific 

 (Taranets, 1937; Schmidt, 1950). A third subspecies in 

 the southeastern North Pacific was recognized by Moiseev 

 ( 1953 ) and Wihmovsky et al. ( 1967 ). Although both authors 

 split eastern Pacific populations into two subspecies, Moi- 

 seev (1953) considered the northern subspecies to be L. b. 

 bilineata and the southern subspecies to be L. b. umbrosa. 

 whereas Wilimovsky et al. (1967) applied the names L. b. 

 perarcuata and L. b. bilineata to northern and southern 

 populations, respectively. 



Our study arose from an examination of collections from 

 ichthyoplankton surveys conducted from the Bering Sea 

 to northern California by the Recruitment Processes Task 

 (referred to simply as "Task" in the following account) of 

 the Alaska Fisheries Science Center (AFSC). In 1985, ich- 

 thyoplankton taxonomists began to routinely separate an 

 unidentified pleuronectid from numerous collections. Larvae 

 from the developmental series of this unidentified pleuro- 

 nectid most closely resembled larvae previously described 

 as Psettichthys melanostictus (Hickman, 1959; Pertseva- 

 Ostroumova, 1961) and, for the following few years, larval 

 pigment patterns and morphological characters were used 

 to separate what were then considered Psettichthys into two 

 readily distinguishable morphotypes. Thus in 1986, an early 

 draft of the Task's laboratory guide (Matarese et al., 1989) 

 included illustrations of an unidentified series referred to 

 as a variant of Psettichthys ("Psettichthys 2"). 



During winter and spring 1987, larvae of both morpho- 

 types of "Psettichthys" were collected from Puget Sound 

 and reared through transformation and settlement stages, 

 and upon examination of the reared juveniles, Kendall 

 and Matarese' determined that larvae previously referred 

 to as "Psettichthys 2" were, in fact, another form of Lepi- 

 dopsetta. From the early results of this work, Matarese et 

 al. (1989) decided to include a partial description of the 

 unknown pleuronectid (referred to as "Lepidopsetta 2") and 

 compared various stages with larvae of Psettichthys and 

 other Lepidopsetta. Mulligan et al. (1995) finally verified 

 the identity of Lepidopsetta 2 by rearing larvae spawned 

 from Lepidopsetta adults collected in Puget Sound and 

 conducted a morphological study of adults. Although they 

 reported significant heterogeneity in shape, structure, and 

 allozymes, they recommended the retention of Wilimovsky 

 et al.'s ( 1967) subspecies designations. 



Although previous authors (Townsend, 1936, 1937: Wili- 

 movsky et al., 1967; Mulligan et al., 1995) concluded that 

 observed variation represented a cline smoothly grading 

 from California through the Bering Sea to Japan and sup- 

 ported subspecific designations, new data became available 

 in 1992 with the development of a fishery for Lepidopsetta 

 in the northern Gulf of Alaska. Domestic fisheries observ- 



ers (see "Acknowledgments" section) experienced in sam- 

 pling in the Bering Sea flatfish fisheries began to report 

 the presence of two syntopic adult forms of Lepidopsetta 

 in the northern Gulf of Alaska, one distinctly different 

 from the form in the eastern Bering Sea. These obser- 

 vations spurred a further examination into the morpho- 

 logical differences of all life stages of Lepidopsetta . Our 

 revision therefore incorporates evidence from adult, juve- 

 nile, and larval morphology and distribution to support 

 the recognition of three species, one described as new, in 

 the North Pacific. We describe morphological variation in 

 adults, juveniles, and larvae; differentially diagnose adults, 

 juveniles, and lai-vae; and describe geographic and bathy- 

 metric distributions of the three species. 



Materials and methods 



Unless indicated otherwise, standard length (SL) is used 

 throughout. Institutional abbreviations follow Leviton et 

 al. (1985) and Leviton and Gibbs (1988), as modified by 

 Poss and Collette (1995), except for the Kamchatka Insti- 

 tute of Ecology, abbreviated as KIE.^ 



Adult morphology 



Meristic data, except gill-raker counts, and morphometric 

 data were taken from the ocular-side of adult material, fol- 

 lowing Hubbs and Lagler ( 1958) with the following excep- 

 tions. Standard, head, and snout length were measured 

 from the anterior margin of the maxilla, with the mouth 

 closed. Body depth was the greatest depth measured at the 

 origin of the anal fin. Head length included only the oper- 

 cle and not the opercular membrane. Snout length was 

 measured to the anterior edge of the dorsal orbit. Cheek 

 length was the greatest distance from the posterior rim 

 of the ventral orbit to the edge of the preopercle, often 

 the posterior angle of the preopercle. Interorbital width 

 equals the least bony width. Pectoral-fin length was the 

 length of the longest ray, often the third ray, and was mea- 

 sured for both ocular-side and blind-side fins. Lateral-line 

 arch length was the distance between anterior and poste- 

 rior flexion points, and this straight line was used as the 

 base for the depth measurement. Greatest caudal peduncle 

 depth was measured at the base of the caudal fin. 



All rayed elements were included in counts of fin rays. 

 The last two rays of the dorsal and anal fins were counted 

 separately. Scales above the lateral line were counted on a 

 diagonal at the greatest depth between the dorsal-fin base 

 and lateral line. Scales below the lateral line were counted 

 from the anal-fin origin on a diagonal to the lateral line. 

 Total scales above and below the lateral line is the sum 

 of the two counts. Cheek scales were counted at greatest 

 cheek length. Ocular-side suborbital pores were counted 



' Kendall, A. W., Jr. and A. C. Matarese. 1987. Unpubl. data. 

 Resource Assessment and Conser\'ati()n Engineering Division, 

 Alaska Fisheries Science Center, Natl. Mar Fish. Serv-., NOAA, 

 7600 Sand Point Wav NE, Seattle, WA 98115. 



- Sheiko, B. 1997. Personal commun. Kamchatka Institute of 

 Ecology, Partizanskaya 6, Petrcpavlovsk-Kamchatsky 683000. 

 Russia. Present address: Department of Ichthyology, Zoologi- 

 cal Institute, Russian Academy of Sciences, Universitetskaynab. 

 1, St. Petersburg 1990.34. Russia. 



