Eulophias spinosior, Nakayama & Yamakawa & Takami & Endo, 2023

Nakayama, Naohide, Yamakawa, Takeshi, Takami, Munehiro & Endo, Hiromitsu, 2023, Description of a New Deep-Water Eulophiid Fish (Perciformes: Zoarcoidei) from Japan, Ichthyology & Herpetology 111 (1), pp. 87-97 : 88-94

Eulophias spinosior , new species

urn:lsid:zoobank.org:act:1968C0FF-1C74-474A-865F-D64CDCE9996B

New standard Japanese name: Toge-itoginpo

Figures 1–5 , Table 1

Eulophias owashii (not Okada and Suzuki, 1954): Kudō et al., 1969: 97 (listed; Tosa Bay).

Holotype.— BSKU 107826 , 1 , M, 182.3 mm SL, Tosa Bay , 33811.2 0 N, 133835.0 0 E, 257–290 m depth, FRV Kotaka-maru, otter trawl, 8 June 1998.

Paratypes.— 70 specimens, 94.9–180.2 mm SL. Tosa Bay : BSKU 47206 , 1 , F, 171.2 mm SL, FRV Kotaka-maru, otter trawl, 11 January 1990 ; BSKU 82966 , 1 , M, 167.7 mm SL, BSKU 82967 , 1 , M, 167.4 mm SL, BSKU 82970 , 1 , M, 163.1 mm SL, BSKU 82971 , 1 , M, 160.1 mm SL, BSKU 82972 , 1 , F, 160.9 mm SL, BSKU 82974 , 1 , M, 162.4 mm SL, BSKU 82975 , 1 , U, 94.9 mm SL, KAUM-I. 100034 (ex. BSKU 82968 ), 1, F, 168.6 mm SL, KAUM-I. 100035 (ex. BSKU 82969 ), 1, M, 167.2 mm SL, 33811.7 0 N, 133836.0 0 E, 306–308 m depth, FRV Kotaka-maru, otter trawl, 11 June 1997 ; BSKU 83206 , 1 , F, 180.2 mm SL, BSKU 83207 , 1 , M, 167.2 mm SL, BSKU 83208 , 1 , M, 162.0 mm SL, BSKU 83211 , 1 , F, 163.4 mm SL, BSKU 83213 , 1 , M, 163.7 mm SL, BSKU 83214 , 1 , F, 151.4 mm SL, BSKU 83215 , 1 , F, 156.3 mm SL, BSKU 83216 , 1 , M, 159.0 mm SL, BSKU 83217 , 1 , F, 134.6 mm SL, NSMT-P 140579 (ex. BSKU 83210 ), 1, M, 168.8 mm SL, NSMT-P 140580 (ex. BSKU 83212 ), 1, F, 156.8 mm SL, 33810.2 0 N, 133833.9 0 E, 308–313 m depth, FRV Kotaka-maru, otter trawl, 17 July 1997 ; BSKU 83420 , 1 , M, 173.8 mm SL, BSKU 83421 , 1 , U, 148.0 mm SL, 33810.1 0 N, 133833.8 0 E, 306 m depth, FRV Kotaka-maru, otter trawl, 9 September 1997 ; CSIRO H 8736-01 (ex. BSKU 83990 and BSKU 83991 ), 2, U, 109.1–114.3 mm SL, USNM 451536 (ex. BSKU 83988 ), 1, U, 152.9 mm SL, USNM 451537 (ex. BSKU 83989 ), 1, U, 129.2 mm SL, 33810.1 0 N, 133833.8 0 E, 293–298 m depth, FRV Kotaka-maru, otter trawl, 9 October 1997 ; BSKU 83993 , 1 , M, 168.5 mm SL, BSKU 83994 , 1 , F, 163.9 mm SL, BSKU 83996 , 1 , F, 151.4 mm SL, BSKU 83997 , 1 , U, 139.1 mm SL, BSKU 83998 , 1 , U, 122.6 mm SL, BSKU 83999 , 1 , U, 109.7 mm SL, BSKU 84000 , 1 , U, 117.5 mm SL, 33810.6 0 N, 133834.4 0 E, 300–302 m depth, FRV Kotaka-maru, otter trawl, 14 November 1997 ; AMS I.49680-001 (ex. BSKU 84012 ) 1, U, 140.5 mm SL, AMS I.49680-002 (ex. BSKU 84015 ) 1, U, 137.7 mm SL, BSKU 84003 , 1 , F, 170.3 mm SL, BSKU 84004 , 1 , M, 168.7 mm SL, BSKU 84009 , 1 , U, 143.7 mm SL, BSKU 84010 , 1 , U, 144.6 mm SL, BSKU 84011 , 1 , F, 153.8 mm SL, BSKU 84013 , 1 , U, 141.4 mm SL, BSKU 84014 , 1 , U, 134.1 mm SL, BSKU 84016 , 1 , F, 134.7 mm SL, BSKU 84017 , 1 , U, 118.6 mm SL, CAS-ICH 247267 (ex. BSKU 84018 and BSKU 84019 ), 2, U, 115.7–118.4 mm SL, HUMZ 231884 (ex. BSKU 84005 ), 1, F, 158.1 mm SL, HUMZ 231885 (ex. BSKU 84008 ), 1, M, 156.1 mm SL, 33810.5 0 N, 133834.1 0 E, 286–289 m depth, FRV Kotaka-maru, otter trawl, 4 December 1997 ; BSKU 118751 , 1 , M, 174.5 mm SL, BSKU 118753 , 1 , F, 179.9 mm SL, BSKU 118756 , 1 , M, 155.1 mm SL, BSKU 118757 , 1 , M, 158.0 mm SL, BSKU 118758 , 1 , M, 174.0 mm SL, BSKU 118759 , 1 , M, 154.6 mm SL, collected with holotype ; BSKU 118798 , 1 , U, 155.0 mm SL, off Niyodo River , 300 m depth, FRV Tosa-kaiyo-maru, otter trawl, T. Ohkawa, 27 January 2016 ; BSKU 118835 , 1 , U, 135.3 mm SL, BSKU 118837 , 1 , F, 133.2 mm SL, 300 m, FRV Tosa-kaiyo-maru, otter trawl, T. Ohkawa, 14 October 2015 ; BSKU 118840 , 1 , F, 161.6 mm SL, 33810.7 0 N, 133834.5 0 E, 298–302 m depth, FRV Kotaka-maru, otter trawl, 11 February 1998 ; BSKU 119420 , 1 , F, 166.0 mm SL, BSKU 119423 , 1 , F, 167.5 mm SL, 300 m depth, FRV Kotaka-maru, otter trawl, 9 March 1998 ; BSKU 119428 , 1 , F, 164.6 mm SL, FAKU 85791 , 1 , M, 168.2 mm SL, FAKU 85792 , 1 , M, 159.1 mm SL, FAKU 85794 , 1 , M, 170.6 mm SL, 33811.6 0 N, 133835.6 0 E, 290–300 m depth, FRV Kotaka-maru, otter trawl, 25 January 1998 ; FAKU 202873 , 1 , M, 160.5 mm SL, FAKU 202874 , 1 , F, 163.6 mm SL, FAKU 202875 , 1 , F, 170.7 mm SL, FAKU 202878 , 1 , F, 162.5 mm SL, 33810.6 0 N, 133834.4 0 E, 284–302 m depth, FRV Kotaka-maru, otter trawl, 11 September 1998 . Kumano-nada : FAKU 34629 , 1 , F, 150.8 mm SL, not fully counted and measured, Owase, H. Asano, O. Okamura, and K. Amaoka, 12–14 November 1961 . Suruga Bay : MSM-21-3, 1, F, 162.4 mm SL, Heda, bottom trawl, 15 October 2015 .

Diagnosis.— Eulophias spinosior is readily distinguished form its two congeners by having 133–143 dorsal-fin spines (vs. 124–128 and 116–125 in E. koreanus and E. tanneri , respectively), 109–116 anal-fin soft rays (vs. 102–103 and 90–100, respectively), 146–156 total vertebrae (vs. 141–143 and 132–143, respectively), and 5–6 pectoral-fin rays (vs. 7 in both E. koreanus and E. tanneri ). In addition, the new species is unique among the genus in lacking prominent dark markings on the sides of the head and body, whereas E. koreanus and E. tanneri have a dark band posterior to the eye and a series of dark blotches midlaterally on the trunk and tail.

Description.— General features are shown in Figures 1–2 . Counts and measurements are given in Table 1 . The following description is based on the male holotype ( Fig. 1 ) unless otherwise stated; data and comments in parentheses are for paratypes.

Body long, slender, eel-like, cylindrical anteriorly, progressively compressed posteriorly; body width at anal-fin origin 1.3 (1.1–1.5) in depth at same level. Trunk moderately short, preanal length 2.3 (2.1–2.5) in tail length. Head small, short, length 11.2 (10.0–12.7) in SL. Snout short, bluntly pointed in lateral view, broadly rounded in dorsal view; its dorsal profile steep, forming an angle of about 458 to horizontal axis of head and body. Eye large, oval, positioned dorsolaterally on head. Interorbital space narrow, slightly concave, its fleshy width 4.2 (3.1–6.9) in eye diameter. Mouth small, terminal, slightly oblique; posterior end of upper jaw extending to below midorbit (often slightly anterior to this level); posterodorsal margin of maxilla covered with skin; upper lip free from snout; tip of lower jaw protruding slightly beyond that of upper jaw. Nostril single, tubular; internarial width 1.9 (1.3– 2.9) times as long as nostril length. Posterodorsal margin of gill cover free from temporal region; narrow frill-like fleshy fringe developed along shoulder girdle above pectoral-fin base. Branchiostegal membranes broadly united across, but free from isthmus, with broad posterior free fold. Gill rakers small, conical, armed with very fine spines, 1–2 þ 0–1 þ 9–12 ¼ 11–14 (based on 3 paratypes: BSKU 83206 , BSKU 83207 , and BSKU 83993 ). Anus only slightly separated from anal-fin origin. Large female paratypes ( BSKU 82972 , BSKU 83206 , and BSKU 83211 , 160.9 – 180.2 mm SL) having well-developed ovaries with large ripe eggs of about 1.5–2.4 mm in diameter .

Single robust canine on anterior part of premaxillary ( Fig. 3 ); two robust canines on anterior tip of dentary; other teeth on premaxillary and dentary small, conical, arranged in almost uniserial row, except for anterior half of premaxillary where teeth in 1–2 irregular rows (see the Sexual dimorphism section for interspecific variation). Vomerine and palatine teeth absent.

Cephalic sensory canals narrow, with small but distinct pores ( Fig. 4 ). Nasal pores 2, positioned anterodorsally and posterodorsally to nostril (posterior one closed on right side in BSKU 82967 ); interorbital 1, situated mid-dorsally between posterior margins of pupils; infraorbital pores 7 (usually 7 or 8, rarely 6 or 9–10), serially arranged along ventral margin of eye; preopercular pores 5 and 4 on left and right sides, respectively (usually 4, rarely 3 or 5), obliquely arranged; mandibular pores 3 (rarely 2 or 4), serially arranged along mandibular rami; occipital pores 3 (rarely 4), transversely arranged in occipital region; postorbital pores 5 (rarely 4), anteriormost one immediately posterior to eye, other 4 (or 3) on temporal region. In some paratypes ( BSKU 47206 , BSKU 84013 , BSKU 118751 , and KAUM-I. 100034), single pore present along dorsoventral margin of orbit (supraorbital pore) .

Body covered with sparsely scattered, small, non-imbricate, embedded cycloid scales, except for fins, predorsal region, and area surrounding pectoral-fin base. No apparent lateral lines on body. Head lacking scales.

Dorsal fin long-based, with 139 (133–143) spines and 10 (7–12) unbranched soft rays; all spines short; spinous portion progressively increasing in height posteriorly, but lower than soft portion; dorsal fin originating posterior to vertical through pectoral-fin base; first dorsal pterygiophore inserted between first and second neural spines (usually between first and second, or second and third spines; rarely anterior to first, or between third and fourth spines). Anal fin long-based, with single (2 in BSKU 118840), short, slender spine and 114 (109–116) unbranched soft rays; anal fin originating below base of 35 th (34 th –38 th) dorsal-fin spine; single free pterygiophore present between spinous and soft portions of anal fin (absent in 31 of 70 paratypes). Dorsal and anal fins confluent with caudal fin. Caudal fin small, but distinct; its posterior margin rounded; most rays branched. Pectoral fin short, flaccid, length 4.3 (2.9–5.1) in HL, inserted posterior to hind margin of gill cover. Pelvic fin absent.

Coloration.— When fresh (based on two paratypes, BSKU 118798 and BSKU 118835; Fig. 2 ), body dusky olive in dorsal and lateral views, but mostly white when viewed ventrally; abdomen narrowly pinkish along mid-ventral line; some very faint dusky spots along mid-lateral line on anterior half of body (only in BSKU 118835; Fig. 2F ); head dusky olive dorsally, but generally white below horizontal through midorbit; nape brownish; iris gold, slightly tinged with brilliant green dorsally; lips, and gular and branchiostegal membranes translucent white, but anterior branchiostegal region pinkish internally; dorsal and caudal fins dusky olive; small irregular white spot on posterodorsal margin of caudal fin; anal fin mostly white, becoming olivish posteriorly; pectoral fin white. In 70% ethanol preservative ( Fig. 1 ), head and body uniformly light tan.

Sexual dimorphism.— In males (including holotype), first premaxillary tooth modified into large stout canine, followed by 1–2 irregular rows of small conical teeth, becoming uniserial posteriorly ( Fig. 3A–B ); whereas in females, first canine only slightly enlarged, and other small teeth arranged in distinct two rows, except near posterior margin ( Fig. 3E–F ). In males, anterior two teeth of mandible modified into large stout canines, second larger, followed by one distinct row of small conical teeth ( Fig. 3C–D ); whereas in females, anterior two canines only slightly enlarged, other small teeth arranged in two irregular rows anteriorly, almost uniserial posteriorly ( Fig. 3G–H ). These dimorphisms especially manifested in sexually mature individuals.

Distribution.— Eulophias spinosior is currently known from only Tosa Bay (type locality), the Kumano-nada, and Suruga Bay, all located off the Pacific coasts of southern Japan ( Fig. 5 ). Bathymetric range is 257–555 m, but usually found around 300 m.

Etymology.— The specific epithet spinosior is derived from the comparative of the Latin adjective spinosus, meaning thorny, spiny, or prickly, in alluding to a greater number of dorsal-fin spines of the new species among Eulophias .

Figures

FIG. 1. Holotype of Eulophias spinosior. BSKU 107826, male, 182.3 mm SL, Tosa Bay, 257–290 m depth. (A) Lateral view; (B) close-up lateral, (C) dorsal, and (D) ventral views of the head and trunk. Preserved.

FIG. 2. Fresh specimens of Eulophias spinosior. (A–E) BSKU 118798, paratype, sex undetermined, 155.0 mm SL, Tosa Bay, 300 m depth, soon after capture; (F) BSKU 118835, paratype, sex undetermined, 135.3 mm SL, Tosa Bay, 300 m depth, freshly thawed. (A, F) Lateral views; (B) close-up lateral, (C) dorsal, and (D) ventral views of the head and trunk; (E) close-up lateral view of the posterior part of the tail.

FIG. 3. Illustrations showing sexual dimorphism in dentition of Eulophias spinosior. (A–D) Male, BSKU 83207, paratype, 167.2 mm SL; (E–H) female, BSKU 83206, paratype, 180.2 mm SL. (A, E) Mesial and (B, F) ventral views of the right premaxillary; (C, G) mesial and (D, H) dorsal views of the right dentary.

FIG. 4. Illustrations showing the cephalic sensory pores of Eulophias spinosior. BSKU 118798, paratype, 155.0 mm SL. (A) Dorsal, (B) lateral, and (C) ventral views of the head. Abbreviations: inf, infraorbital pores; int, interorbital pore; man, mandibular pores; n, nostril; nas, nasal pores; occ, occipital pores; pos, postorbital pores; pre, preopercular pores.

FIG. 5. Maps of (A) the northwestern Pacific and (B) southern Japan showing distribution of three species of Eulophias. Stars, circles, and square represent localities of E. spinosior, E. tanneri, and E. koreanus, respectively. ‘‘H’’ indicates the type locality of each species.