Coelorinchus gilberti Jordan & Hubbs, 1925, 1984

Nakayama, Naohide, 2020, Grenadiers (Teleostei: Gadiformes: Macrouridae) of Japan and adjacent waters, a taxonomic monograph, Megataxa 3 (1), pp. 1-383 : 55-60

Coelorinchus gilberti Jordan & Hubbs, 1925 [Japanese name: Oni-hige]

( Figs. 37–39 ; Appendix 3-2C)

Macrurus parallelus (not G̹nther1877): G̹nther1877:439(original description; in part, 2 paralectotypes, BMNH 1887.12.7.67– 68, off Eno-shima Island , Sagami Bay , Challenger sta. 232); G̹nther 1887:125 (description; in part, 2 paralectotypes, BMNH 1887.12.7.67–68, off Eno-shima Island , Sagami Bay, Challenger sta. 232) .

Coelorhynchus japonicus (not Temminck & Schlegel 1846): Jordan & Thompson 1914:306 [2 spec. from Misaki; FMNH 57268 (ex. CM 6207 a)] .

Caelorhynchus gilberti Jordan & Hubbs, 1925:327 [original description; holotype: FMNH 59401 (ex. CM 7960 ), from “fish-market at Shizuoka”] .

Coelorhynchus gilberti : Okada & Matsubara 1938:451 (in key; Japan); Kamohara 1950:277 (listed; Kochi and Wakayama Pref.; Japanese name: “Oni-hige”); Kuroda 1951:392 (listed; Suruga Bay); Kamohara 1952:99 (spec. from Kochi Pref.); Matsubara 1955:1313 (in key; Japan); Kamohara 1958:73 (listed; Kochi Pref.); Kobayashi & Ikeda 1962:20, unnumbered fig.(spec. from Shirikishinai, Pacific off southern Hokkaido); Kamohara 1964:96 (listed; Kochi Pref.); Ueno 1965:19 (listed; Pacific off Hokkaido); Okamura 1970a:201, pl. XLIV, text-fig. 87 (description; 23 spec. from Pacific off Japan from Hokkaido to Misaki); Maruyama 1971:33 (listed; Iwate Pref.); Ueno 1971:101 (listed; Hokkaido); Tominaga & Uyeno 1981:488 (listed; Japan); Okamura 1982:181, 354, fig. 107 (brief description; 8 spec. from Kyushu-Palau Ridge and Tosa Bay; photos based on BSKU 29453 and BSKU 29509); Shiogaki 1982:34 (listed; Aomori Pref.); Sawada 1983:113, 196, fig. 65 (brief description; 4 spec. from Pacific off Tohoku; photo based on HUMZ 87121).

Coelorhynchus kanetomoi Matsubara & Asano, 1943:95 (original description; holotype: SKFC 2, from Misaki, in ca. 700 m; new Japanese name: “Syôno-fue”); Matsubara 1955:1314 (in key; Japan).

[?] Coelorhynchus japonicus (not Temminck & Schlegel 1846): Ueno 1965:19 (listed; Pacific off Hokkaido); Maruyama 1971:33 (listed; Iwate Pref.); Ueno 1971:101 (listed; Hokkaido).

[?] Coelorhynchus parallelus (not G̹nther 1877): Ueno 1965:19 (listed; Pacific off Hokkaido); Ueno 1971:101 (listed; Hokkaido).

Coelorhynchus (Oxymacrurus) gilberti: Okamura 1970b : table 1 (listed; Japan).

Coelorhynchus longicephalus (not Okamura 1982): Okamura 1982:177, fig. 105 [original description; in part, BSKU 26102; Kyushu-Palau Ridge; see Nakayama et al. (2015c)].

Coelorinchus gilberti: Okamura 1984b:97 , pl. 345, fig. J (compiled); Okamura 1988:97, pl. 345, fig. J (compiled); Maeda & Maruyama 1991:366 (listed; Hokkaido); Shiogaki et al. 1992:29 (listed; Aomori Pref.); Amaoka et al. 1995:104, fig. 155 (compiled; northern Japan); Suzuki & Kataoka 1997:84, pl. 34, fig. 184 (brief description; 1 spec. from off Kii Peninsula); Okamura 1997:127, fig. 19 (compiled); Goto 2000:6 (19 spec. from Iwate Pref.); Shinohara et al. 2009:708 (6 spec. listed from Pacific off Tohoku); Nakabo & Kai 2013:509 (in key; Japan); Ikeda & Nakabo 2015:321, pl. 67, fig. 11 (brief description; spec. from Wakayama Pref.); Amaoka et al. 2020:164, fig. 222 (listed; Hokkaido); Motomura 2020:38 (listed; Japan).

[?] Coelorinchus japonicus (not Temminck & Schlegel 1846): Maeda & Maruyama 1991:366 (listed with a question mark; Hokkaido); Amaoka et al. 2020:164, fig. 223 (listed; Hokkaido).

[?] Coelorinchus parallelus (not G̹nther1877): Maeda& Maruyama 1991:366 (listed with a question mark; Hokkaido).

Caelorinchus gilberti: Nakabo 1993:368 (in key; Japan); Shinohara et al. 1996:168 (4 spec. listed from Pacific off Tohoku; 4 spec.); Shinohara & Matsuura 1997:290 (listed; Suruga Bay); Nakabo 2000:432 (in key; Japan); Shinohara et al. 2001:304 (2 spec. listed from Tosa Bay); Nakabo 2002:432 (in key; Japan); Maeda & Tsutsui 2003:488 (listed; Hokkaido); Shiogaki et al. 2004:55 (listed; Pacific off Aomori Pref.; Suetsugu & Ohta 2005: table 3 (listed; Enshu-nada); Senou et al. 2006:420 (listed; Sagami Sea); Kitagawa et al. 2008:41, unnumbered fig. (brief description; spec. from Pacific off Tohoku); Matsuura et al. 2009:24 (1 spec. from Miyagi Pref.); Amaoka et al. 2011:131, fig. 166 (compiled; Hokkaido).

[?] Caelorinchus japonicus (not Temminck & Schlegel 1846): Maeda & Tsutsui 2003:488 (listed with a question mark; Hokkaido).

[?] Caelorinchus parallelus (not G̹nther 1877): Maeda & Tsutsui 2003:488 (listed with a question mark; Hokkaido).

[?] Caelorinchus (Oxygadus) gilberti: Chiou et al. 2004a : table 1 (questionable; listed without voucher spec.; Taiwan).

Caelorinchus anatirostris (not Jordan & Gilbert in Jordan & Starks 1904): Matsuura et al. 2009:24 (1 spec. from Miyagi Pref.; NSMT-P 74846 ) .

Caelorinchus sp .: Matsuura et al. 2009:24 (in part, NSMT-P 74239; 1 spec. from Iwate Pref.).

Diagnosis. No external evidence of light organ anterior to anus. Underside of head almost completely naked; narrow scaly patches usually present on mandibular rami and areas below infraorbital and preopercular ridges; dorsal surface of snout fully scaled, except for narrow naked clefts along each side of median rostral ridge; nasal fossa usually lacking scales. Snout long, sharply pointed, length 67–81% PRL; dorsal profile of snout slightly concave in lateral view; terminal scute moderately short, diamond-shaped, dorsoventrally flattened; lateral nasal ridge incompletely supported by nasal bone. Anus abutting anal-fin origin. Premaxillary teeth small, conical, arranged in short, uniformly wide band, none especially enlarged; posterior end of tooth band falling far short of lateral corner of mouth. Body scales covered with stout, trihedral, shield-like spinules in parallel ridge-like rows; middle row enlarged, giving striated appearance to body surface; lateral rows often incomplete, not extending to posterior scale margin; buttresses broadly developed. Scales on head ridges coarsely modified, highly spiny, and thickened. Occipital scales covered with short, erect, trihedral spinules in narrowly divergent ridge-like rows. Free neuromasts on underside of head modified into prominent, knob-like or flap-like projections; short, dark, hairy papillae densely scattered over ventral surface of head except for mandibular rami. Head and body uniformly dark; orbit narrowly edged in black; lips, oral cavity, and all fins blackish.

Material examined. 30 specimens. Holotype of Caelorhynchus gilberti: FMNH 59401 (ex. CM 7960, 137 mm HL, 478+ mm TL), fish market in Shizuoka, Shizuoka Pref., Japan, coll. D.S. Jordan, Oct.–Nov. 1922 . Paralectotypes of Macrurus parallelus (designated herein): BMNH 1887.12.7.67–68 (2, 63.8–107 mm HL, 221+–355+ mm TL), off Eno-shima Island, Sagami Bay , 35.1833ºN, 139.4667ºE, 345 ftm (631 m), Challenger sta. 232, trawl and dredge, 12 Mar. 1875 . Non-types : Japan : * BSKU 44480 (1, 39.7 mm HL, 150+ mm TL), Tosa Bay , 700 m, FRV Kotaka-maru, 26 Jan. 1988 ; * BSKU 44839 (1, 50.6 mm HL, 186+ mm TL), Tosa Bay , 32.9886ºN, 133.5978ºE, 700–720 m, FRV Kotaka-maru, otter trawl, 21 Jun. 1988 ; BSKU 99459 (1, 60.4 mm HL, 198+ mm TL), Tosa Bay , 33.1900ºN, 133.6883ºE, 542–585 m, FRV Kotaka-maru, otter trawl, coll. H. Endo, 22 Jan. 1998 ; BSKU 44792 (1, 52.6 mm HL, 185+ mm TL) , BSKU 44793 (1, 49.8 mm HL, 160+ mm TL), Tosa Bay , 33.0517ºN, 133.6152ºE, 700 m, FRV Kotaka-maru, 24 May 1988 ; BSKU 46145 (1, 117 mm HL, 416+ mm TL), Tosa Bay , 33.0400ºN, 133.6098ºE, 675–708 m, FRV Kotaka-maru, otter trawl, 22 May 1989 ; BSKU 29509 (1, 85.6 mm HL, 259+ mm TL), Tosa Bay , 32.9167ºN, 133.5500ºE, 700 m, F/ Vs Shinsei-maru, No. 53 and Kyoyo-maru, No. 2, cr. 4- Ky, sta. T20, long line, coll. O. Okamura et al., 21 Dec. 1979 ; BSKU 30494 (1, 40.0 mm HL, 139+ mm TL), Tosa Bay , 32.9667ºN, 133.5333ºE, 605 m, F/ Vs Shinsei-maru, No. 53 and Kyoyo-maru, No. 2, bottom trawl, coll. O. Okamura et al., 21 Dec. 1979 ; BSKU 29453 (1, 177 mm HL, 626+ mm TL), off Kochi, 32.4582ºN, 133.4675ºE, 745–810 m, F/ Vs Shinsei-maru, No. 53 and Kyoyo-maru, No. 2, sta. 4-L4, long line, coll. O. Okamura et al., 21 Dec. 1979 ; BSKU 45516 (1, 193 mm HL, 653+ mm TL), off Tosa-Shimizu, long line, 14 Jul. 1988 ; KPM-NI 18243 (1, 120 mm HL, 425+ mm TL), off Shima Peninsula, Kumano-nada , 34.0144ºN, 136.9054ºE, 767–771 m, R/ V Tansei-maru, cr. KT-04-06, sta. KN-1(2), 3-m ORE beam trawl, coll. T. Sato, 1 May 2004 ; FRLM 3579 (1, 129 mm HL, 455+ mm TL) , FRLM 3580 (1, 130 mm HL, 478 mm TL), off Mie, Kumanonada , long line, coll. Fisheries Research Institute of Mie Pref., 18 May 1982 ; FRLM 8964 (1, 138 mm HL, 522+ mm TL), Kumano-nada, coll. K. Suzuki, date unknown ; FRLM 3577 (1, 108 mm HL, 392+ mm TL), off Mikizaki , Kumano-nada, long line, coll. Fisheries Research Institute of Mie Pref., 18 May 1982 ; NSMT-P 97154 (1, 74.0 mm HL, 236+ mm TL), southeast of Miyake-jima Island, Shichito-Iojima Ridge , 34.1340ºN, 139.6717ºE, 565–644 m, R/ V Tansei-maru, cr. KT-89-06, sta. ME11, 3-m ORE beam trawl, 19 May 1989 ; NSMT-P 101440 (1, 79.2 mm HL, 217+ mm TL), off Oshima Island, Izu Islands , 621– 710 m, R/ V Hakuho-maru, cr. KH-89-test-III, 4-m ORE beam trawl, 5 Sept. 1989 ; BSKU 101982 (1, 28.5 mm HL, 107+ mm TL), off Iwaki , 36.9162ºN, 141.5995ºE, 615–633 m, FRV Wakataka-maru, sta. 49, coll. H. Endo, 4 Nov. 1995 ; BSKU 97953 (1, 83.5 mm HL, 313+ mm TL), off Onahama , 450 m, FRV Wakataka-maru, sta. G-450, coll. D. Kitagawa, 16 Oct. 1997 ; NSMT-P 77845 (1, 162 mm HL, 620 mm TL), off Hitachi , 36.5300ºN, 141.1450ºE, 557–561 m, FRV Wakataka-maru, sta.H-550, bottom trawl, coll. H. Saito et al., 14 Nov. 2006 ; NSMT-P 74691 (1, 149 mm HL, 535 mm TL), off Kesennuma, date unknown; NSMT-P 48953 (1, 130 mm HL, 480 mm TL), NSMT-P 48954 (1, 116 mm HL, 433+ mm TL), off Kuji , 40.0015ºN, 142.3657ºE, 611–617 m, FRV Wakataka-maru, sta. 15, bottom trawl, coll. G. Shinohara, 26 Oct. 1995 ; BSKU 30589 (1, 125 mm HL, 400+ mm TL), Kyushu-Palau Ridge , 27.9000ºN, 134.6500ºE, 910 m, F/ Vs Shinsei-maru, No. 53 and Kyoyo-maru, No. 2, cr. Ky, sta. T-12, bottom trawl, coll. O. Okamura et al., 18 Dec. 1979 ; BSKU 26016 (1, 175 mm HL, 631+ mm TL), Kyushu-Palau Ridge , 27.9000ºN, 134.6417ºE, 720 m, F/ Vs Shinsei-maru, No. 53 and Kyoyo-maru, No. 2, sta. 2-1, bottom trawl, coll. Y. Kobayashi et al., 14 Feb. 1978 ; * BSKU 114872 (1, 107 mm HL, 416 mm TL), eastsoutheast of Cape Erimomisaki , 41.8170ºN, 143.7875ºE, 576 m, FRV Wakataka-maru, sta. H-550, otter trawl, coll. R. Misawa, 6 Jun. 2014 ; NSMT-P 76191 (1, 130 mm HL, 487+ mm TL), off Hokkaido, T/ V Oshoro-maru, sta. OST-2, coll. T. Yanagimoto, 16 Sept. 2005 .

Counts and measurements. Based on 27 specimens (28.5–193 mm HL, 107+–653+ mm TL). Counts: first dorsal-fin rays II,7–8; pectoral-fin rays i16–i19; pelvicfin rays 6–7; gill rakers on first arch (outer/inner) 0–2/7– 10, on second arch 6–7/8–9; longitudinal scales 35–45; transverse scale rows below first dorsal-fin origin 5.5–8, below first dorsal-fin midbase 4.5–7, below second dorsalfin origin 5–7, above anal-fin origin 17–23.

The following measurements are in % of HL, followed by those in % of PRL in parentheses: snout length 40–45 (67–81); orbit diameter 23–28 (39–47); postorbital length 30–37 (52–62); postrostral length 56–61; orbit–preopercle distance 31–39 (55–65); suborbital width 11–15 (18–25); upper-jaw length 22–27 (39–44); length of rictus 17–23 (30–39); length of premaxillary tooth band 8–12 (14–20); preoral length 36–45 (59–80); length of terminal snout scute 7–11 (12–20); length of lateral nasal ridge 28–34 (47–60); length of suborbital ridge 92–97 (153–174); snout width 24–31 (39–55); internasal width 17–22 (28– 36); interorbital width 21–23 (37–41); occipital width 8–10 (13–18); body width over pectoral-fin bases 31– 47 (54–83); body depth at first dorsal-fin origin 41–58 (73–96); body depth at anal-fin origin 30–48 (53–81); prepelvic length 99–116 (167–193); preanus length 127–155 (225–255); preanal length 130–162 (230–266); isthmus–pelvic distance 22–34 (38–57); isthmus–anus distance 47–75 (83–123); isthmus–anal distance 50–82 (89–135); pelvic–anal distance 30–52 (53–87); anus–anal distance 3–7 (4–12); pelvic-fin length 27–44 (46–73); pectoral-fin length 31–40 (55–66); predorsal length 105– 111 (177–196); height of first dorsal fin 30–41 (52–68); length of first dorsal-fin base 12–17 (21–28); interdorsal length 10–24 (18–41); length of gill slit 10–14 (18–24); length of posterior nostril 5–10 (9–16); barbel length 3– 12 (6–20).

Size. Attains at least 65 cm TL (BSKU 45516, 653+ mm TL, off Tosa-Shimizu, Kochi, Japan).

Distribution. Japan and the Emperor Seamounts ( Iwamoto & Okamoto 2015; this study; Appendix 3-2C). In Japan, known from the upper continental slope along the Pacific coasts from Hokkaido to Shikoku and the Kyushu-Palau Ridge.Depth range 400– 930 m.Moderately common in the Pacific off northern Honshu (Tohoku), but rare in the west of the Boso Peninsula (139.89ºE).

Remarks. For further morphological information see the original description ( Jordan & Hubbs 1925) and Okamura (1970a). Coelorinchus gilberti is common in the Pacific off northern Japan, dominating museum specimens of the genus collected from the area.

While Shao (1993) recorded C. gilberti from Taiwan, it seems to represent a different species of Coelorinchus . Shao’s (1993) specimen is the only record of C. gilberti from Taiwan, but unfortunately, it is presumed lost ( Chiou et al. 2004a: table 1). The occurrence of C. gilberti in Taiwanese waters was therefore not verified in this study.

Nomenclatural discussion. Coelorinchus gilberti was described from a single specimen obtained at a fish market in Shizuoka, Shizuoka Pref., Japan ( Fig. 38 ). Subsequently, Matsubara & Asano (1943) described C. kanetomoi based on a single specimen collected from off Misaki, Kanagawa Pref., Japan (probably from Sagami Bay). The holotype of C. kanetomoi was registered in the Sigenkagaku Fish Collection of the Research Institute for Natural Resources, Tokyo (SKFC 2), but apparently lost during WWII (see also the Comments on holotype of C. hige ). Okamura (1970a) later included C. kanetomoi in the synonymy of C. gilbert without explanation.

According to Matsubara & Asano (1943:98) and Matsubara (1955:1313–1314), C. kanetomoi can be distinguished from C. gilberti by having the following combination of features: spinules of body scales arranged in 8–11 convergent rows (vs. 5 parallel rows in C. gilberti ); snout length twice as long as orbit diameter (vs. less than two times as long as orbit); interorbital width only slightly greater than interdorsal space (1.33 times vs. about 1.5 times as long as first dorsal-fin base length); pelvic-fin length about equal to pectoral-fin length (vs. shorter than pectoral-fin length); and two narrow scaly patches below infraorbital ridge (vs. underside of head entirely naked). However, the holotype of C. kanetomoi (586 mm TL, fide Matsubara &Asano 1943:95) is much larger than that of C. gilberti (478+ mm TL), and the differences in squamation appear to reflect ontogenetic or individual variation. To a certain extent, the number of spinule rows increases with size in grenadiers ( Iwamoto & Merrett 1997:509) and also differs on different parts of the body. In addition, the scaly patches on the underside of the head are usually absent in smaller specimens of C. gilberti . The differences in the measurements are also less pronounced or even negligible when considering the range of variation of the C. gilberti examined: snout length 1.53–1.91 times as long as orbit diameter; interorbital width 1.33–1.84 times as long as first dorsal-fin base length; and pectoral-fin length 0.87– 1.30 in pelvic-fin length. Consequently, no significant differences were found between the two nominal species, and C. kanetomoi is confirmed as a junior synonym of C. gilberti .

Relationships. Coelorinchus gilberti belongs to a group of Coelorinchus species characterized by the following combination of features: no external evidence of light organ anterior to anus; lateral nasal ridge incompletely supported by nasal bone; premaxillary teeth in short, uniformly wide band; underside of head entirely or almost entirely naked; body scales covered with shield-like spinules in parallel to subparallel rows, with middle row largest and some rows incomplete; buttresses of spinules broadly developed; scales on head ridges coarsely modified, highly spiny, and thickened; body uniformly dark brown to swarthy; lips and oral cavity blackish. This group is called here the C. occa group, in which the following eight valid species are included: C. anisacanthus Sazonov, 1994 fromtheEmperorSeamounts; C. aratrum Gilbert, 1905 and C. doryssus Gilbert, 1905 from Hawaii; C. gilberti ; C. labiatus (K̂hler, 1896) from the northeastern Atlantic; C. mediterraneus Iwamoto & Ungaro, 2002 from the Mediterranean; C. obscuratus McMillan & Iwamoto, 2009 from New Zealand to New Caledonia; and C. occa ( Goode & Bean, 1885) from the western Atlantic. This group is closely related to the C. parallelus group (see the Relationships of C. divergens ), with which it is considered to comprise the subgenus Oxygadus Gilbert & Hubbs, 1920 (type species C. parallelus ). The C. parallelus group readily differs from the C. occa group in having the underside of the head completely or almost completely scaled (vs. completely or mostly naked).

Comparisons. Coelorinchus gilberti is readily distinguished from other species of the C. occa group except C. occa by the presence of short, dark, hairy papillae densely scattered over the ventral surface of the head except the mandibular rami (vs. absent). It further differs from all but C. occa in having prominent flap-like (knob-like in well-preserved specimens) black neuromasts serially arranged on the underside of the head. In the other species, the neuromasts are relatively small, unpigmented, and scarcely discernible without a microscope. Coelorinchus gilberti is readily distinguished from C. mediterraneus in that naked areas along each side of the median rostral ridge are only narrowly developed (vs. broadly developed). It also differs from C. anisacanthus , C. doryssus , C. labiatus , and C. mediterraneus by head squamation: in C. gilberti , scales on dorsal surfaces of the head are strongly spinulated, which gives a spiny appearance to these areas, whereas in the latter four species, the spinulation is less pronounced, giving more or less smooth texture to the surfaces. Coelorinchus gilberti differs from C. occa in that scaly patches are only narrowly developed (or even absent) on the mandibular rami and areas below the infraorbital and preopercular ridges (vs. broadly developed in C. occa ).

Figures

FIGURE 37. Fresh specimens of Coelorinchus gilberti. (A) BSKU 29453, 177 mm HL, 626+ mm TL, off Kochi Pref., Pacific., 745–810 m depth; (B–C) BSKU 114872, 107 mm HL, 416 mm TL, east-southeast of Cape Erimomisaki, Hokkaido, Pacific, 576 m depth; (E) BSKU 46145, 117 mm HL, 416+ mm TL, Tosa Bay, Kochi Pref., Pacific, 675–708 m depth; (F) BSKU 44839, 50.6 mm HL, 186+ mm TL, Tosa Bay, 700–720 m depth; (G) BSKU 44480, 39.7 mm HL, 150+ mm TL, Tosa Bay, 500 m depth. (A–B, E–G) Lateral views; (C) dorsal and (D) ventral views of the head and trunk. [Photos: (A, E–G) BSKU; (B–D) N. Nakayama]

FIGURE 38. Holotype of Caelorhynchus gilberti (= Coelorinchus gilberti). FMNH 59401, 137 mm HL, 478+ mm TL, fish market in Shizuoka (probably from Suruga Bay), Pacific. (A) Lateral view (snout broken and bent upwards); (B) dorsal and (C) ventral views of the head and trunk. Preserved condition. [Photos: N. Nakayama]

FIGURE 39. Scanning electron micrographs showing a body scale (from the dorsum below the interdorsal space) of Coelorinchus gilberti. NSMT-P 76191, 130 mm HL. (A) View from above; (B) oblique view. [Photos: N. Nakayama]