Bull. Natl. Mus. Nat. Sci., Ser. A, 35(4), pp. 227–232, December 22, 2009 Taxonomic Notes on the Rare Eelpout, Davidijordania lacertina (Perciformes, Zoarcidae) Gento Shinohara1 and Ik-Soo Kim2 1 Department of Zoology, National Museum of Nature and Science, 3–23–1 Hyakunin-cho, Shinjuku-ku, Tokyo, 169–0073 Japan E-mail: [email protected] 2 Department of Biology, College of Natural Sciences, Chonbuk National University, Chonju, 560–756 Republic of Korea E-mail: [email protected] Abstract Morphological characters of the rare eelpout, Davidijordania lacertina, were revised based on a specimen collected from the Sea of Japan off South Korea in 1993. Davidijordania lac- ertina likely comprises a monophyletic group with Davidijordania poecilimon and Davidijordania yabei in sharing an apomorphic condition: dark stripes on the head. The Korean specimen is the first occurrence from outside Russia for the species. Key words : Zoarcidae, Davidijordania lacertina, morphology, Sea of Japan, South Korea. and Fedorov, 2004), two additional specimens Introduction (69 and 170 mm in total length: TL) were report- The zoarcid Davidijordania lacertina was ed from Peter the Great Bay (type locality) originally described by Pavlenko (1910) as Ly- by Lindberg and Krasyukova (1975). Recently, cenchelys lacertinus on the basis of three syn- Balanov et al. (2006) reported two specimens types from Peter the Great Bay. The genus Da- (140–157 mm TL) from Peter the Great Bay and vidijordania was established for the species by briefly described some morphological characters. Popov (1931). According to Anderson and Fe- In 1993, a single specimen of D. lacertina was dorov (2004), this genus contains the following collected from the Sea of Japan off the Korean four species: Davidijordania brachyrhyncha Peninsula near the border between the Republic (Shmidt, 1904), Davidijordania jordaniana of Korea and the Democratic People’s Republic Schmidt, 1936, Davidijordania poecilimon (Jor- of Korea. We herein describe the external and in- dan and Fowler, 1902) and D. lacertina. Recent- ternal morphologies of this specimen. ly, Anderson and Imamura (2008) described Da- vidijordania yabei based on 11 specimens from Materials and Methods Japan and Russia. All species except for D. poe- cilimon are very rare (Sokolovskaya et al., 1998; The specimen examined here is deposited in Fedorov et al., 2003) and the genus is in need of the Department of Biology, College of Natural revision (Anderson and Fedorov, 2004). Especial- Sciences, Chonbuk National University, Republic ly, detailed morphological data of the type of Korea (CNUC); comparative specimens in the species (D. lacertina) has been lacking. Hokkaido University Museum, Hakodate Schmidt (1936) added Vladimir Bay (Russia) (HUMZ), the National Museum of Nature and to the distribution of D. lacertina, but did not Science, Tokyo (NSMT) and the National give detailed specimen data. Except for three Musuem of Natural History, Smithsonian Institu- syntypes (whereabouts unknown, see Anderson tion (USNM). Counts were made from radi- 228 Gento Shinohara and Ik-Soo Kim ographs, and measurements with digital caliper Table 1. Counts and proportional measurements of to the nearest 0.1 mm following Anderson Davidijordania lacertina from South Korea and Russia. (1982). Standard length (SL) and head length Balanov et al. (HL) are used throughout. CNUC 34536 Osteological characters were observed from (2006) both radiographs and three-dimensional skull im- nϭ1 nϭ2 ages constructed from X-ray CT scanning equip- SL (mm) 161ϩ 138–154 ment for laboratory animals (LCT-100; Aloka, Counts Tokyo). Precaudal vertebrae 22 22 Caudal vertebrae 94ϩ 98 Total vertebrae 116ϩ 120 Systematic Accounts Pectoral fin rays 17 15–16 Pelvic fin rays 3 3 Order Perciformes Pseudobranch filaments 4 4–5 Vomerine teeth 4 3 Suborder Zoarcoidei Palatine teeth 13–14 10–11 Nasal pores 2 2 Family Zoarcidae Interorbital pores 1 1 Davidijordania lacertina (Pavlenko, 1910) Suborbital pores 7 6–7 Postorbital pores 4 4–5 [New Korean name: Kin-munzagalchi] Occipital pores 2 3 [Japanese name: Naga-sarasagaji] Mandibular pores 4 4 Preopercular pores 4 4 (Figs. 1–4, Table 1) Proportional measurements (% HL) Snout length 24.3 24.4–24.8 Lycenchelys lacertinus Pavlenko, 1910: 53, figs. 10–11 Eye diameter 18.9 20.5 (original description, Peter the Great Bay); Soldatov Upper jaw length 48.7 45.4–46.7 and Lindberg, 1930: 499. Gill slit length 24.3 4.4–28.6 Davidojordania lacertina [sic]: Schmidt, 1936: 99 (Peter the Great Bay and Vladimir Bay); Lindberg and Krasyukova, 1975: 174, fig. 135 (keys, description, Peter the Great Bay). length 48.7%; postorbital head length 55.7%; Davidijordania lacertina: Matsubara, 1955: 780 (key); pectoral fin length 55.6%; pelvic fin length Toyoshima, 1984: 305; Andrianov and Kussakin, 1998: 63.3%. Vertebrae more than 116 [ϭ22 (abdomi- 327 (list); Sokolovskaya et al., 1998: 7 (list); Anderson nal vertebrae)ϩmore than 94 (caudal)]; dorsal fin and Fedorov, 2004: 4, 43 (list); Balanov et al., 2006: rays more than 108 (last ray remains on 89th cau- 256 (description, Peter the Great Bay). dal vertebra); anal fin rays more than 90 (last ray Material examined. CNUC 34536, 1 speci- remains on 90th caudal vertebra); pectoral fin men, male, 161.5ϩmm SL (25.9 mm HL), Sea of rays 17; pelvic fin rays 3; gill rakers 1ϩ1ϩ9ϭ Japan off Mukho-dong Donhae City, Kanwon-do, 11; pseudobranch filaments 4; pyloric caeca 2, South Korea (37°31ЈN, 129°02ЈE), April 1993 nub-like. Body elongate, compressed laterally, (date unknown). cross section elliptical. Scales absent on head, Description. Because tail tip is broken, stan- nape and fin membranes, but present on body in- dard and total lengths cannot be measured. Pre- cluding abdomen. Dorsal fin origin above poste- dorsal length about equal to HL (101.5% HL); rior end of opercle. Opercular flap at upper mar- prepectoral length slightly larger than HL gin of gill slit well developed. Pectoral fin origin (103.1%); preanal length slightly smaller than at about level of body midline. Posterior margin twice of HL (196.9%). Proportions in HL: body of pectoral fin almost rounded. Pelvic fins pre- depth 40.9% at pelvic fin origin and 27.4% at sent. Lateral line mediolateral, incomplete, ends anal fin origin; prepelvic fin length 88.0%; snout in anterior part of abdomen. Head large, its dor- length 24.3%; eye diameter 18.9%; interorbital sal profile convex at snout. Nostril tube small, width 3.9%; gill slit length 24.3%; upper jaw not reaching upper lip when pressed forward. Taxonomy of Davidijordania lacertina 229 Fig. 1. Davidijordania lacertina, CNUC 34536, 161ϩmm SL, from the Sea of Japan off Korea. Mouth large, posterior end of upper jaw extend- plate-like, the others tube-like. Premaxilla com- ing beyond a vertical line through posterior end prising a short ascending process and long, of pupil. Eye ovoid, not entering dorsal profile of dentigerous premaxillary process (Fig. 3). Maxil- head. Interorbital space narrow, flattened. Gill slit la long and robust. Retroarticular firmly attached wide, extending below a horizontal between 14th to anguloarticular. Mesopterygoid attached to ec- and 15th pectoral fin rays. Both jaws with en- topterygoid and separated from metapterygoid larged conical teeth; anterior teeth in a patch, and quadrate. Metapterygoid with a notch for others in a single row. Four teeth on vomer; 14 symplectic dorsoposteriorly. Metapterygoid artic- teeth on palatine (13 in right). Head pores small, ulating with hyomandibula and symplectic poste- rudimentary: nasal pores 2; interorbital pore 1; riorly. Hyomandibula with three articular heads suborbital pores 7; postorbital pores 4; occipital dorsally, anterior two attached to neurocranium pores 2; preoperculomandibular pores 8. and posteriormost to opercle and not elongate. Coloration in preservative. Dark stripes on Preopercle crescent-shaped, with 3 pores (preop- dorsal and lateral surface of head (Figs. 1–2). erculomandibular pores 6–8 in Fig. 2) opening Anterior 1/3 of upper lip heavily pigmented ven- from interior canal; 4 pores (preoperculo- trally; anterior tip of lower lip slightly pigmented. mandibular pores 1–4) arising from dentary and Ventral midline and adjacent areas of head with 1 (pore 5) from anguloarticular. Opercle triangu- dark pigment. Ventral half of body with isolated lar. Ceratohyal-epihyal juncture smooth. Bran- groups of large dark spots in which 3 form an chiostegal rays 4ϩ2ϭ6, anterior 4 on ceratohyal angle and sometimes fused to one another. and remainder on epihyal. Posttemporal long, Osteology. Six suborbital bones present, form- ventral ramus weak. ing semicircle around eye, the first largest and Remarks. The specimen can be identified as D. 230 Gento Shinohara and Ik-Soo Kim Fig. 2. Head pores and pigmentation of Davidijordania lacertina, CNUC 34536. IO, interorbital pore; NS, nasal pores; OC, occipital pores; PO, postorbital pores; SO, suborbital pores. Numbers indicate preoperculo- mandibular pores. Taxonomy of Davidijordania lacertina 231 Fig. 3. CT scanning images of Davidijordania lacertina, CNUC 34536. Top, dorsal view; middle, left side of lateral view; bottom, right side of lateral view. Fig. 4. Dorsal view of Davidijordania lacertina. From Pavlenko (1910: fig. 10). lacertina in having the following characters: snout length more than eye diameter; ventral half slightly higher counts in pectoral fin rays and of body with isolated groups of large dark spots palatine teeth (Table 1), this is intraspecifically in which 3 form an angle and sometimes fused to variable in zoarcids (see Anderson, 1982, 1994). one another. There are two morphological groups in the 5 Although Lindberg and Krasyukova (1975) species of Davidijordania (Anderson and Ima- showed an illustration of a specimen of D. lac- mura, 2009). Group 1 (sensu Anderson and Ima- ertina without dark stripes or dark blotches on mura, 2008) containing D. brachyrhyncha and D. the head, Pavlenko’s original description (Fig. 4) jordaniana, is defined by less than 110 vertebrae showed that this species had the bands and and slightly restricted gill slit.