Bull. Natl. Mus. Nat. Sci., Ser. A, 38(1), pp. 33–47, February 22, 2012 Taxonomy of Lycodes matsubarai Toyoshima, 1985 and Lycodes yamatoi Toyoshima, 1985 (Perciformes, Zoarcidae) Mikhail V. Nazarkin1 and Gento Shinohara2 1 Zoological Institute RAS, Universitetskaya, 1, Saint-Petersburg, Russia, 199034 E-mail: [email protected] 2 National Museum of Nature and Science, 4–1–1 Amakubo, Tsukuba, Ibaraki, 305–0005 Japan E-mail: [email protected] (Received 7 December 2011; accepted 6 January 2012) Abstract Two nominal eelpouts, Lycodes matsubarai Toyoshima, 1985 from the southern Sea of Okhotsk and Lycodes yamatoi Toyoshima, 1985 from the Sea of Japan, were reinvestigated based on the types and additional specimens collected from Japan and adjacent waters. Several disagree- ments were recognized between the original descriptions and type specimens for L. yamatoi, and its diagnostic distinctions from L. matsubarai were no longer valid. Lycodes yamatoi is identical with L. matsubarai, and the latter name is kept for this species. A redescription is provided with some taxonomic remarks. Key words : Teleostei, Zoarcidae, eelpouts, synonymy, redescription, Sea of Japan, Sea of Okhotsk. and Kukhlevsky, 2011; Savely’ev et al., 2011; Introduction Sokolovsky et al., 2011; Shinohara et al., 2011). Two very similar nominal eelpouts, Lycodes Lycodes yamatoi attains 403 mm TL (Savely’ev et matsubarai and Lycodes yamatoi, were simulta- al., 2011). neously described in the same publication (Toyo- During joint research on the demersal fish shima, 1985). Both taxa belong to Toyoshima’s fauna of the Sea of Japan and the Sea of species group D with a ventrolateral lateral line, Okhotsk, we had an opportunity to examine the and are characterized by submental crests moder- type specimens of L. matsubarai and L. yamatoi ately high and not fused anteriorly, pectoral fin and additional specimens from Japan and adja- without a notch, brownish peritoneum, body cent waters (Fig. 1). Several disagreements were coloration with several light vertical stripes and revealed between the original descriptions of L. vertebral numbers usually more than 100. yamatoi and the type specimens. The holotypes According to Toyoshima (1985), Lycodes of both eelpouts are considerably decalcificated, matsubarai is known only from the area of and it was impossible to count vertebrae. But the southern shelf of the Sea of Okhotsk, adjoining paratypes of L. yamatoi have almost the same northeastern Hokkaido where it was collected at vertebral counts as those of L. matsubarai. All depths of 128–480 m, and attains 364 mm total characters reinvestigated here, including diagno- length (TL). Nanbu et al. (1992) reported this ses given by Toyoshima (1985), were found to species from the Sea of Japan for the first time. widely overlap between the two nominal species, On the other hand, Lycodes yamatoi is common thus L. yamatoi is identical with L. matsubarai. and widely distributed in the Sea of Japan on the According to the International Code of Zoologi- bottom at depths of 155–600 m (Toyoshima, cal Nomenclature (1999), at the simultaneous 1985; Balanov and Solomatov, 2008; Balanov description of taxa with equal rank, priority is 34 Mikhail V. Nazarkin and Gento Shinohara Tokyo). Vertebrae and other osteological ele- ments were examined from radiographs. Mea- surements were made with calipers to the nearest 0.1 mm. Head length (HL) and standard length (SL) are used throughout with total length (TL). Specimens are deposited in the following institu- tions: Hokkaido University Museum, Hakodate, Japan (HUMZ); Maizuru Fisheries Research Sta- tion, Kyoto University, Maizuru (FAKU); National Museum of Nature and Science, Tokyo (NSMT); Osaka Museum of Natural History (OMNH). All specimens were collected from the Sea of Japan or the Sea of Okhotsk (Fig. 1). Order Perciformes Suborder Zoarcoidei Family Zoarcidae Lycodes matsubarai Toyoshima, 1985 Fig. 1. Collection localities of Lycodes matsubarai [Japanese name: Matsubara-genge] (stars), Lycodes yamatoi (squares) and additional (Figs. 2–3, Tables 1–3) specimens examined here (crosses). — Solid star and square, holotypes; open stars and squares, Lycodes matsubarai Toyoshima, 1985, p. 218, fig. 53; paratypes. Maeda and Maruyama, 1991, p. 372; Nanbu et al., 1992, p. 71, fig. 1; Hatooka, 1993, p. 908, fig.; Ander- son, 1994, p. 118; Amaoka et al., 1995, p. 247; Hatooka, 2000, p. 1039, fig.; Hatooka, 2002, p. 1039, established by the First Reviser (Article 24.2.1 fig; Maeda and Tsutsui, 2003, p. 499; Müller and and 24.2.2). In the present work, we prefer to use Gravlund, 2003, p. 383; Anderson and Fedorov, 2004, L. matsubarai (discussed below), and rede- p. 26; Fedorov, 2004: p. S93; Nazarkin, 2010a, p. 9. scribed the species. Lycodes yamatoi Toyoshima, 1985, p. 208, fig. 49; Maeda and Maruyama, 1991, p. 372; Hatooka, 1993, p. 908, fig.; Anderson, 1994, p. 119; Amaoka et al., 1995, p. Materials and methods 246; Hatooka, 2000, p. 1039, fig.; Hatooka, 2002, p. 1039; Maeda and Tsutsui, 2003, p. 499; Møller and Methods for making counts and measurements Gravlund, 2003, p. 385; Anderson and Fedorov, 2004, follow Anderson (1994) except for isthmus width p. 31; Fedorov, 2004, p. S93; Nazarkin, 2010b, p. 603; which is measured between lower ends of the gill Balanov and Kukhlevsky, 2011, p. 447; Savely’ev et openings. The first postorbital head pore (postor- al., 2011, p. 31; Sokolovsky et al., 2011, p. 246, fig. 94B; Shinohara et al., 2011, p. 52. bital 1 sensu Anderson, 1994) in this species, as Lycodes cf. yamatoi: Balanov and Solomatov, 2008, p. 14. well as in some other species of Lycodes, actu- ally connects with the suborbital canal. This pore Materials examined. Sea of Okhotsk speci- is thus identical with part of the suborbital head mens–HUMZ 33970 (holotype of Lycodes mat- pore series, but we follow Anderson (1994) for subarai): 324 mm TL, male, southern part of head pore terminology for comparable results. Kitami-Yamato Bank (44°47′N, 144°01.5′E), Head pores were observed by staining with 200 m depth, 31 Oct. 1974; HUMZ 33948, Methylene Blue (Kanto Chemical Co., Inc., 33971–33972, 33974–33979, 33981, 33983 Taxonomy of two Japanese eelpouts 35 Fig. 2. Type and additional specimens of Lycodes matsubarai. — A, HUMZ 33970, male (holotype of L. matsubarai, Sea of Okhotsk); B, HUMZ 41094, male (holotype of Lycodes yamatoi, Sea of Japan); C, NSMT-P 67295, female (Sea of Japan); D, HUMZ 53740, female (paratype of L. yamatoi, Sea of Japan); E, FAKU 131994, female (Sea of Japan); F, HUMZ 53738, male (paratype of L. yamatoi, Sea of Japan). Sizes showing TL. 36 Mikhail V. Nazarkin and Gento Shinohara Fig. 3. Color changes from fresh condition (insets) just after capture to alcohol preserved condition in Lycodes matsubarai. — A, NSMT-P 99968 (309 mm TL, female, Sea of Japan near Oki Islands, 250–251 m); B, NSMT-P 67247 (252 mm TL, female, Sea of Japan, Yamato Bank, 619–623 m). bs, branchial stripe. (paratypes of L. matsubarai): 268–332 mm TL, Bank (39°31.41′N, 135°45.71′E), 619–623 m, 26 10 males and 1 female, (45°12.5′N, 143°6.5′E), Aug. 2003; NSMT-P 67295: 125–145 mm TL, 1 128 m, 27 Oct. 1975; HUMZ 33950, 33960, juvenile (sex unknown) and 1 female, Yamato 33968–33969 (paratypes of L. matsubarai): 316– Bank, 28 Mar. 2003; NSMT-P 99968, 310 mm 364 mm TL, 3 males and 1 female, (45°2.5′N, TL, female, near Oki Island (36°1.75′N, 144°5′E), 235 m, 31 Oct. 1974; HUMZ 49095 132°34.25′E), 250–251 m, 14 May 2009; (nontype): 301 mm TL, male, 45°37′N, 143°53′E; OMNH-P 17943–17947: 257–282 mm TL, 3 HUMZ 49096 (paratype of L. matsubarai): males and 2 sex unknown, Sea of Japan, Kita- 314 mm TL, female, (45°37′N, 143°53′E), 290– yamato Bank; FAKU 3841, 3842: 254 mm, 480 m, 8 Oct. 1975. female and 247 mm TL, male, Yamato Bank, Sea of Japan specimens–NSMT-P 61212: 322– (39°04′N, 134°32′E), 363–480 m, 20 June 1982; 342 mm TL, 2 sex unknown, Honshu, off Shima ne FAKU 3850: 257 mm TL, male, Yamato Bank Pref. (35°38.9′N, 132°1.1′E), 210–220 m, 17 Sep. (39°05′N, 134°30′E), 354–401 m depth, 19 July 1982; NSMT-P 64992: 198–321 mm TL, 2 males 1982; FAKU 3923: 323 mm TL, female, Oki and 2 females, R/V Tanshu-maru, 2 July 2002; Bank, (37°44′N, 133°46′E), 380–514 m depth, 7 NSMT-P 67247: 252 mm TL, female, Yama to June 1982; FAKU 3924: 262 mm TL, sex Taxonomy of two Japanese eelpouts 37 Table 1. Proportional measurements of Lycodes matsubarai and Lycodes yamatoi with additional specimens. Additional Lycodes matsubarai Lycodes yamatoi specimens Paratypes Paratypes Nontypes Holotype Holotype (n＝16) (n＝29) (n＝27) 324.0 mm 323.0 mm 268.0–364.0 mm 156.5–368.0 mm 203.0–335.0 mm TL TL TL TL TL % TL Predorsal length 22.5 21.5–24.7 (23.1) 26.0 21.9–28.3 (25.6) 23.1–27.4 (25.5) Preanal length 38.8 38.6–41.5 (39.9) 41.7 38.1–44.2 (41.5) 38.9–45.3 (41.9) Prepectoral length 20.1 18.4–21.5 (20.1) 21.4 19.7–24.6 (21.6) 18.5–24.5 (21.4) Prepelvic length 16.2 14.4–18.1 (16.4) 17.2 14.7–21.5 (17.1) 14.2–22.2 (16.8) Pectoral fin length 12.3 10.9–14.6 (12.3) 11.7 11.1–15.7 (12.5) 10.8–14.2 (12.1) Pelvic fin length 1.1 1.0–1.5 (1.2) 1.1 0.4–1.7 (0.9) 0.6–1.5 (1.0) Pectoral fin base height 5.3 4.6–5.7 (5.2) 5.6 4.7–6.7 (5.5) 4.1–6.2 (5.4) Gill slit length 7.0 6.7–7.9 (7.2) 8.2 6.8–9.2 (7.8) 6.4–9.1 (8.0) Isthmus width 4.3 3.4–4.7 (4.1) 4.8 3.6–6.0 (4.5) 3.1–5.6 (4.6) Longest dorsal fin ray length 4.9 3.9–4.9 (4.3) 4.6 3.7–6.1 (4.7) 3.9–6.0 (4.8) Longest anal fin ray length 3.2 3.2–4.3 (3.7) 3.9 3.3–5.0 (4.2) 3.1–5.1 (4.1) Caudal fin length 2.1 1.9–2.7 (2.2) 1.7 1.4–3.0 (2.1) 1.3–2.6 (2.1) Body depth at anal origin 10.5 9.7–10.9 (10.2) 10.4 8.9–10.8 (9.8) 8.8–11.4 (10.1) Head length (HL) 19.4 18.1–20.9 (19.5) 21.2 18.8–24.6 (20.8) 18.3–22.5 (20.5) % HL Snout length 33.2 28.8–33.1 (31.7) 32.5 27.1–33.9 (31.4) 28.0–33.0 (31.0) Eye diameter 15.8 14.7–18.9 (16.5) 15.6 12.1–19.7 (16.4) 13.8–21.2 (16.7) Interorbital width (skin) 17.9 12.3–19.8 (16.1) 15.2 11.9–17.6 (14.7) 12.3–22.1 (15.8) Interorbital width (bone) 3.2 3.2–5.2 (3.8) 3.4 3.1–5.0 (3.9) 2.9–5.0 (4.1) Upper jaw length 47.5 37.5–51.4 (45.4) 42.5 33.4–51.3 (40.7) 34.5–47.7 (42.1) Numbers in parentheses indicating average.