Coryphaenoides rudis Günther, 1878

[Japanese name: Daikoku-hige]

(Figs. 129–130; Appendix 3-7D)

Coryphaenoides rudis G̹nther, 1878:24 [original description; lectotype: BMNH 1889.12.7.74, from west of Kermadec Islands, Challenger sta. 171, in 600 ftm (1097 m); in part, see the Comments on type specimens]; Gilbert & Hubbs 1916:144 (lectotype designation; listed); Shao et al. 2008b: table 2 (1 spec. listed from South China Sea; first record from Taiwan); Iwamoto et al. 2015:73, fig. 11 (brief description; 2 spec. from South China Sea and southeastern Taiwan); Nakayama & Endo 2016a:7, figs. 2j–l, 3 (first record from Japan; 6 spec. from Hyuga-nada, Suruga Bay, and Minami-torishima Island; re-examination of lectotype; comments on type specimens; new Japanese name: “Daikoku-hige”); Motomura 2020:39 (listed; Japan).

Macrourus paradoxus Smith & Radcliffe in Radcliffe, 1912:115, pl. 25, fig. 1 [original description; holotype: USNM 72932, from off eastern Palawan Island, 9º13′00ʺN, 118º51′15ʺE, in 1105 ftm (2021 m)] .

Nematonurus macrocephalus Maul, 1951:17, figs. 3, 4c [original description; holotype: MMF 898 (mounted), from off Madeira; 2 paratypes in BMNH and MMF].

Coryphaenoides macrocephalus: Iwamoto 1990:212, fig. 490 (synopsis).

Diagnosis. Pelvic-fin rays 9–10. Snout bluntly pointed, slightly protruding beyond upper jaw. Tip and lateral angles of snout armed with small scute-like scales; scales along head ridges slightly enlarged and thickened. Mouth large, posterior margin of upper jaw extending slightly beyond vertical through midorbit; upper-jaw length 35– 42% HL; lateral corner of mouth not restricted by skin folds. Outermost gill slit greatly restricted, length 5–7% HL.Barbel long, slender, length14–23% HL. Premaxillary teeth in broad tapered bands with outer series notably enlarged; dentary teeth in narrow tapered band with inner series enlarged. Body scales covered with long, reclined, needle-like spinules in tightly packed convergent rows or quincunx order; tip of last spinule in each row extending beyond posterior scale margin (except for larger adults). Transverse scale rows below first dorsal-fin midbase 6.5– 9. Head fully scaled, lacking naked areas on snout. Height of first dorsal fin less than HL (76–84% HL); second spinous ray serrated along its leading edge; first dorsalfin rays II,9–10. Outer pelvic-fin ray slightly prolonged, its tip usually extending beyond anal-fin origin. Body uniformly dark brown.

Material examined. 7 specimens. Lectotype of Coryphaenoides rudis: BMNH 1887.12.7.74 (168 mm HL, 814+ mm TL), west of Kermadec Islands, 28.5500ºS, 177.8333ºE, 600 ftm (1098 m), Challenger sta. 171, trawl, 15 Jul. 1874. Non-types: Japan: MSM 93-18 (1, 62.6 mm HL, 336 mm TL), Suruga Bay, F / V Nishimiya-maru, crab trap, 10 Mar. 1993 ; BSKU 49468 (1, 127 mm HL, 599+ mm TL), BSKU 49570 (1, 64.8 mm HL, 322+ mm TL), BSKU 49577 (1, 75.7 mm HL, 384+ mm TL), off Miyazaki, Hyuga-nada, 32.3083ºN, 132.1817ºE, 1453– 1481 m, R/ V Shinkai-maru, 3 Apr. 1991; HUMZ 72029 (1, 248 mm HL, 1079+ mm TL), HUMZ 72030 (1, 269 mm HL, 1200+ mm TL), between Shichito-Iojima Ridge and Marcus Island, 23.9333ºN, 150.6000ºE, 1100–1160 m, 10 Oct. 1977.

Counts and measurements. Based on 7 specimens (62.6–269 mm HL, 322+–1200+ mm TL). Counts: first dorsal-fin rays II,9–10; pectoral-fin rays i19–i23; pelvicfin rays 9–10; gill rakers on first arch (outer/inner) 1–5/9– 11, on second arch 8–10/9–11; longitudinal scales 31–40; transverse scale rows below first dorsal-fin origin 8.5– 11, below first dorsal-fin midbase 6.5–9, below second dorsal-fin origin 5.5–8.5, above anal-fin origin 29–36; pyloric caeca 13–14.

The following measurements are in % of HL, followed by those in % of PRL in parentheses: snout length 24–30 (31–40); orbit diameter 18–23 (23–31); postorbital length 53–61 (71–78); postrostral length 74– 79; orbit–preopercle distance 48–59 (64–75); suborbital width 13–15 (18–20); upper-jaw length 35–42 (47–55); length of rictus 29–36 (39–46); length of premaxillary tooth band 25–29 (33–37); preoral length 9–15 (12–21); distance between tip and lateral angle of snout 10–15 (13– 20); snout width 19–25 (24–33); internasal width 18–23 (23–31); interorbital width 28–31 (37–40); body width over pectoral-fin bases 37–67 (51–87); body depth at first dorsal-fin origin 86–96 (111–124); body depth at anal-fin origin 64–85 (84–108); prepelvic length 103–115 (136– 149); preanus length 155–156 (200–204); preanal length 160–177 (206–231); isthmus–pelvic distance 42–52 (55–68); pelvic–anal distance 60–75 (77–98); pelvic-fin length 44–76 (60–98); pectoral-fin length 49–62 (63–81); predorsal length 113–119 (146–155); height of first dorsal fin 76–84 (97–111); length of first dorsal-fin base 24–30 (31–40); interdorsal length 20–38 (26–48); length of gill slit 5–7 (6–10); length of posterior nostril 6–8 (8–10); barbel length 14–23 (18–31).

Size. Attains at least 120 cm TL (Iwamoto & Graham 2001; this study). The specimen HUMZ 72030 collected from off the Shichito-Iojima Ridge is one of the largest specimens of the species (1200+ mm TL).

Distribution. Widespread in tropical and temperate waters of the world’s oceans at depths of 980–2400 m (Sazonov & Iwamoto 1992; Shcherbachev & Iwamoto 1995; Iwamoto & Williams 1999; Merrett & Iwamoto 2000; Iwamoto & Graham 2001; Shao et al. 2008a, 2008b; Melo et al. 2010; Nakayama & Endo 2016a). In Japan, so far known from Hyuga-nada, Suruga Bay, and the Shichito-Iojima Ridge off Minami-torishima Island, at depths of 1100–1481 m (Nakayama & Endo 2016a; Appendix 3-7D). Rare.

Remarks, relationships, and comparisons. Coryphaenoides rudis is a widespread species, being a senior synonym of both C. paradoxus (Smith & Radcliffe in Radcliffe, 1912) and C. macrocephalus (Maul, 1951) . For further morphological details see Iwamoto and Sazonov (1988;as C. paradoxus).The species was recently recorded from Japan by Nakayama & Endo (2016a) based on the specimens examined here. They considered that Franz’s (1910) record of the species from Abratsubo, Kanagawa Pref., Japan, represented a misidentification of a species of a different genus.

Coryphaenoides rudis is a member of the subgenus Coryphaenoides (sensu Iwamoto 1990) . Among Japanese congeners, it is most similar to C. soyoae Nakayama & Endo, 2016, but differs from the latter in having body scales covered with spinules arranged in tightly packed convergent rows or quincunx order (Fig. 130 vs. narrowly divergent rows; Fig. 133), fewer pelvic-fin rays (9–10 vs. 11), smaller body scales (transverse scale rows 8.5–11 vs. 7–7.5 below first dorsal-fin origin; 6.5–9 vs. 4–5 below first dorsal-fin midbase), a broader interorbital space (28–31% HL vs. 24–27%), and a lower first dorsal fin (76–84% HL vs. 87%), and in lacking a naked area on the underside of the snout (vs. present).

Coryphaenoides soyoae Nakayama & Endo, 2016

(Figs. 131–133; Appendix 3-7E)

[Japanese name: Kuro-hige]

Coryphaenoides soyoae Nakayama & Endo, 2016a:2, figs. 1, 2a–c (original description; holotype BSKU 20297, from Shichito-Iojima Ridge, in 2740 m; 1 paratype from off Onahama; new Japanese name: “Kuro-hige”); Motomura 2020:39 (listed; Japan).

Diagnosis. Pelvic-fin rays 11. Snout bluntly pointed, only slightly protruding beyond upper jaw. Terminal snout scute absent; scales on lateral angles of snout and infraorbital ridge slightly enlarged and thickened. Dorsal contour of head prominently humped over nape, with distinct depression above orbits. Orbit diameter 20–21% HL. Mouth large, posterior margin of upper jaw extending to below hind 1/3 of orbit or beyond; upper-jaw length 35–40% HL; lateral corner of mouth not restricted by skin folds. Outermost gill slit greatly restricted, length 7–8% HL. Barbel well developed, slender, length 11–15% HL. Teeth in tapered bands in both jaws, with outer premaxillary series distinctly enlarged. Body scales covered with long, reclined, needle-like spinules in slightly divergent rows; tip of last spinule in each row extending well beyond posterior scale margin; middle row not especially higher than adjacent rows. Transverse scale rows below first dorsal-fin midbase 4–5. Snout fully scaled dorsally, but naked ventrally. Interdorsal space slightly less than first dorsal-fin base length. Height of first dorsal fin less than HL (87% HL); second spinous ray serrated along its leading edge; first dorsal-fin rays II,9–10. Pectoral-fin rays i19–i22. Outer pelvic-fin ray greatly prolonged, extending well beyond anal-fin origin. Body uniformly blackish.

Material examined. 2 specimens. Holotype of Coryphaenoides soyoae: BSKU 20297 (120 mm HL, 578+ mm TL), between Izu and Ogasawara Islands, Shichito-Iojima Ridge, Japan, 30.0000ºN, 140.5417ºE, 2740 m, FRV Soyo-maru, sta. 4, bottom trawl, 18 Nov. 1972 . Paratype of C. soyoae: NSMT-P 78018 (1, 73.7 mm HL, 365+ mm TL), off Onahama, 36.8050ºN, 142.3717ºE, 2948–2991 m, FRV Soyo-maru, cr. SO-07-02, benthos net, coll. H. Saito and M. Okanishi, 2 Aug. 2007 .

Counts and measurements. Based on 2 specimens (73.7–120 mm HL, 365+–578+ mm TL). Counts: first dorsal-fin rays II,9–10; pectoral-fin rays i19–i22; pelvicfin rays 11; gill rakers on first arch (outer/inner) 5–6/11– 12, on second arch 8–9/10; longitudinal scales 34–37; transverse scale rows below first dorsal-fin origin 7–7.5, below first dorsal-fin midbase 4–5, below second dorsalfin origin 7, above anal-fin origin 26.

The following measurements are in % of HL, followed by those in % of PRL in parentheses: snout length 27–29 (36–39); orbit diameter 20–21 (26–28); postorbital length 55–56 (74–75); postrostral length 74; orbit–preopercle distance 49 (66); suborbital width 13–14 (18); upper-jaw length 35–40 (47–53); length of rictus 29–32 (38–43); preoral length 12–14 (16–19); distance between tip and lateral angle of snout 14–15 (19–20); snout width 23–24 (31–33); internasal width 21–23 (28–31); interorbital width 24–27 (33–36); body width over pectoral-fin bases 48–56 (65–75); body depth at first dorsal-fin origin 85–90 (114–121); body depth at anal-fin origin 70–76 (94–101); prepelvic length 110–116 (148–156); preanus length 152–159 (204–214); preanal length 158–165 (212–223); isthmus–pelvic distance 45– 46 (60–62); pelvic–anal distance 43–52 (58–69); pelvicfin length 66–84 (89–113); pectoral-fin length 49 (66); predorsal length 109–116 (147–156); height of first dorsal fin 87 (117); length of first dorsal-fin base 27–28 (36–38); interdorsal length 23–24 (30–32); length of gill slit 7–8 (9–11); length of posterior nostril 6 (7–8); barbel length 11–15 (15–20).

Size. Attains about 58 cm TL (BSKU 20297, holotype, 578+ mm TL, Shichito-Iojima Ridge, Japan) .

Distribution. So far known only the Pacific off Onahama, Fukushima, and the Shichito-Iojima Ridge, at depth of 2740–2991 m (Appendix 3-7E). Very rare.

Remarks, relationships, and comparisons. Coryphaenoides soyoae was recently described by Nakayama & Endo (2016a), to which readers can refer for a full description of the species. In Japanese waters, C. soyoae is most closely similar to C. rudis G̹nther, 1878, but they can be distinguished from each other by the combination of the body-scale spinulation, head squamation, numbers of transvers scale rows, interdorsal length, and height of the first dorsal fin (see the Remarks, relationships, and comparisons for the latter species).

Coryphaenoides yaquinae Iwamoto & Stein, 1974 [Japanese name: Shinkai-yoroidara]

(Figs. 99B, 100 C–D, 134; Appendix 3-7F)

Coryphaenoides yaquinae Iwamoto & Stein, 1974:34, figs. 15A, 20 (original description; holotype: USNM 211795, from Tufts Abyssal Plain, R/V Yaquina sta. TP-3, 44º39.9ʹN, 133º37.2ʹW, in 3724 m; 2 paratypes from off California): Endo & Okamura 1992:433, fig. 1 (first record from Japan; brief description; 28 spec. fromnorthwesternPacific;newJapanesename:“Shinakiyoroidara”); Nakabo 1993:363 (in key; Japan); Okamura 1997:124, fig. (compiled); Nakabo 2000:427 (in key; Japan); Nakabo 2002:427 (in key; Japan); Senou 2008:367, fig. 31.35 (in situ observation; Japan Trench); Shinohara et al. 2009:708 (listed; Pacific off Tohoku); Nakabo & Kai 2013:503 (in key; Japan); Amaoka et al. 2020:162, fig. 218 (listed; Hokkaido); Motomura 2020:39 (listed; Japan).

[?] Coryphaenoides sp.: Senou 2008:367, fig. 31.36 (in situ observation; Chishima Trench).

Diagnosis. Pelvic-fin rays usually 10, rarely 9 or 11. Snout rounded in adults (pointed in young specimens), slightly protruding beyond upper jaw. Tip and lateral angles of snout armed with small scute-like scales; scales along head ridges slightly thickened but not especially enlarged. Mouth large, posterior margin of upper jaw almost reaching vertical through hind rim of orbit; upper-jaw length 37–41% HL; lateral corner of mouth not restricted by skin folds. Outermost gill slit moderately wide, length 18–22% HL. Barbel long, stout at base, length 13–21% HL. Teeth conical, sharply pointed; premaxillary teeth in 2–3 irregular rows or narrow band, with outer series enlarged; mandibular teeth in 2 irregular rows near symphysis, uniserial row posteriorly. Body scales covered with short, reclined, needle-like to knife-like spinules in subparallel to narrowly divergent rows; tip of last spinule in each row extending to posterior scale margin or slightly beyond. Transverse scale rows below first dorsal-fin midbase 6–7.5. Top of snout narrowly naked posterior to leading edges; underside of head almost completely naked. Interdorsal space greater than first dorsal-fin base length. Height of first dorsal fin less than HL (62–82% HL); second spinous ray not prolonged, with serrated leading edge; first dorsalfin rays II,8–10. Body uniformly dark brown.

Material examined. 23 specimens. Japan: BSKU 49883 (1, 59.6 mm HL, 325 mm TL), BSKU 49884 (1, 77.0 mm HL, 412 mm TL), Japan Trench, 5500 m, R/ V Hakuho-maru, cr. KH-91-6, sta. 18, 6 Nov. 1991 ; NSMT-P 78028 (1, 133 mm HL, 685+ mm TL), off Kinakzan, 4000 m, FRV Soyo-maru, benthos net, coll. H. Saito, 7 Aug. 2007 ; NSMT-P 78022 (1, 82.7 mm HL, 441+ mm TL), NSMT-P 78023 (1, 118 mm HL, 610+ mm TL), NSMT-P 78024 (1, 115 mm HL, 565+ mm TL), NSMT-P 78025 (1, 90.2 mm HL, 537+ mm TL), off Kushiro, 5700 m, FRV Soyo-maru, sta. Kago-6, coll. H. Saito, 1–2 Aug. 2007; NSMT-P 19033 (1, 69.5 mm HL, 371+ mm TL), off Aogashima Island, Izu Trench, 31.1750ºN, 141.7017ºE, 5100 m, 30 Jul. 1976 ; NSMT-P 30198 (1, 86.3 mm HL, 467+ mm TL), NSMT-P 30201 (1, 86.4 mm HL, 468+ mm TL), east of Shichito-Iojima Ridge, western Pacific, 30.0967ºN, 146.9267ºE, 6160 m, R/ V Hakuho-maru, fish trap, 11 May 1982 ; BSKU 35735 (1, 99.3 mm HL, 534+ mm TL), BSKU 35736 (1, 91.5 mm HL, 521+ mm TL), BSKU 35737 (1, 88.7 mm HL, 488+ mm TL), east of Japan Trench, 38.5650ºN, 145.2617ºE, 5350–5370 m, R/ V Hakuho-maru, cr. KH-81-4, sta. 11, 1 Aug. 1981 ; BSKU 37301 (1, 92.8 mm HL, 495+ mm TL), east of Cape Inbozaki, east of Japan Trench, 35.8333ºN, 145.2000ºE, 4100 m, 1981 ; BSKU 35726 (1, 69.1 mm HL, 377+ mm TL), BSKU 35727 (1, 73.7 mm HL, 396 mm TL), BSKU 35729 (1, 78.0 mm HL, 448+ mm TL), BSKU 35730 (1, 86.8 mm HL, 478+ mm TL), Kesennuma, Japan Trench, 38.5550ºN, 144.3233ºE, 6380–6450 m, R/V Hakuhomaru, cr. KH-81-4, sta. 12, 31 Jul. 1981 ; BSKU 49930 (1, 67.3 mm HL, 311+ mm TL), Japan Trench, 38.7342ºN, 144.1233ºE, 5500 m, R/ V Hakuho-maru, cr. KH-91- 6, sta. 16-2, 18 Nov. 1991 ; * BSKU 35734 (1, 107 mm HL, 553+ mm TL), east of Japan Trench, 38.5650ºN, 145.2617ºE, 5350–5370 m, R/ V Hakuho-maru, cr. KH-81-4, sta. 11, 1 Aug. 1981 ; BSKU 35720 (1, 69.0 mm HL, 356+ mm TL), off Kamaishi, Japan Trench, 39.1883ºN, 143.9067ºE, 5010–5109 m, R/ V Hakuho-maru, cr. KH-81-4, sta. 10, 25 Jul. 1981 ; BSKU 19997 (1, 70.1 mm HL, 362+ mm TL), BSKU 19999 (1, 88.4 mm HL, 498+ mm TL), east of Japan Trench, 33.9750ºN, 142.8550ºE, 5200 m, FRV Soyo-maru, beam trawl, 4 Jun. 1970 .

Counts and measurements. Based on 22 specimens (59.6–133 mm HL, 311+–685+ mm TL). Counts: first dorsal-fin rays II,8–10; pectoral-fin rays i18–i20; pelvicfin rays 9–11; gill rakers on first arch (outer/inner) 6–10/11–13, on second arch 10–13/11–13; longitudinal scales 29–38; transverse scale rows below first dorsalfin origin 6.5–10.5, below first dorsal-fin midbase 6–7.5, below second dorsal-fin origin 7–10, above anal-fin origin 26–34; pyloric caeca 9.

The following measurements are in % of HL, followed by those in % of PRL in parentheses: snout length 25–30 (32–41); orbit diameter 19–22 (25–29); postorbital length 54–59 (72–77); postrostral length 74–78; orbit–preopercle distance 44–49 (58–66); suborbital width 10–13 (13–17); upper-jaw length 37–41 (49–56); length of rictus 33–37 (44–50); length of premaxillary tooth band 27–33 (35– 43); preoral length 10–16 (12–22); distance between tip and lateral angle of snout 11–15 (14–20); snout width 20– 25 (25–33); internasal width 16–20 (21–26); interorbital width 24–29 (32–38); occipital width 1–6 (2–8); body width over pectoral-fin bases 44–74 (57–96); body depth at first dorsal-fin origin 78–99 (104–128); body depth at anal-fin origin 60–80 (80–103); prepelvic length 99–122 (127–163); preanus length 168–201 (219–261); preanal length 175–205 (230–266); isthmus–pelvic distance 36– 50 (47–64); isthmus–anus distance 101–135 (134–178); isthmus–anal distance 109–140 (144–185); pelvic–anal distance 71–101 (96–134); anus–anal distance 5–11 (6– 14); pelvic-fin length 66–86 (85–112); pectoral-fin length 60–77 (78–101); predorsal length 111–125 (148–162); height of first dorsal fin 62–82 (81–111); length of first dorsal-fin base 24–35 (32–45); interdorsal length 39– 58 (52–75); length of gill slit 18–22 (23–29); length of posterior nostril 4–7 (6–9); barbel length 13–21 (18–28); length of pyloric caecum 35 (45).

Size. Attains about 77 cm TL (Wilson & Waples 1983; Mecklenburg et al. 2002).

Distribution. Known from the North and Central Pacific below a depth of about 3400 m (Iwamoto & Stein 1974; Wilson & Waples 1983; Iwamoto 1990; Endo & Okamura 1992; Mecklenburg et al. 2002; this study). In Japan, known only from the Japan, Izu-Ogasawara, and Kuril-Kamchatka Trenches at depths of 4000‾ 7433 m (Appendix 3-7F). Moderately common in its depth range.

Remarks. For further morphological information see the original description given by Iwamoto & Stein (1974); see also Wilson & Waples (1983) who provided a detailed comparison between C. yaquinae and C. armatus (Hector, 1875) . Coryphaenoides yaquinae is restricted in the Pacific Ocean, and was first reported from Japan by Endo & Okamura (1992). The previous deepest record for the species was 6380–6450 m, based on by five specimens collected from the Japan Trench (BSKU 35726–35730, 69.0– 86.8 mm HL, 377+–478+ mm TL; Endo & Okamura 1992). Using a baited camera lander, Jamieson et al. (2009) also observed the species at 6945 m in the same area. One of the specimens examined (NSMT-P 98009, 115 mm HL, 585+ mm TL) was collected from the Japan Trench at a depth of 7340–7433 m; this represents a new deepest record for C. yaquinae .

Relationships and comparisons. Coryphaenoides yaquinae belongs to the subgenus Nematonurus (sensu Iwamoto 1990), and is most similar to C. armatus . For a comparison between the two species see the Relationships and comparisons for the latter species.