Coelorinchus macrochir (Günther, 1877)

Nakayama, Naohide, 2020, Grenadiers (Teleostei: Gadiformes: Macrouridae) of Japan and adjacent waters, a taxonomic monograph, Megataxa 3 (1), pp. 1-383 : 100-105

Coelorinchus macrochir (Günther, 1877)

[Japanese name: Tenaga-dara]

( Figs. 67–69 ; Appendix 3-4B)

Macrurus macrochir G̹nther, 1877:438 [original description; holotype: BMNH 1887.12 .7.123, from “off Inoshima ” (= Eno-shima Island), Challenger sta. 232, at a depth of 345 ftm (631 m)]; G̹nther 1887:48, pl. XXIX, fig. B (further description of holotype) .

Abyssicola macrochir : Jordan & Snyder 1900 (spec. from off Tokyo); Jordan & Snyder 1901:119 (listed; Japan); Jordan & Gilbert in Jordan & Starks 1904:607 (3 spec. from Sagami Bay); Franz 1910:26 (1 spec. from Aburatsubo); Jordan et al. 1913:414 (listed; Japan; new Japanese name: “Tenagadara”); Gilbert & Hubbs 1916:183 (description; 36 spec. from East China Sea, Hyuga-nada, and Pacific off Tohoku); Schmidt 1931:154 (brief description; 2 spec. from Misaki and Tokyo); Okada & Matsubara 1938:450 (in key; Japan); Kamohara 1938:71 (brief description; 1 spec. from Kochi Pref.); Kamohara 1950:279 (listed; Kochi Pref.); Kuroda 1951:392 (listed; Suruga Bay); Kamohara 1952:98 (3 spec. from Kochi Pref.); Kuroda 1952:177 (brief description; 3 spec. from Suruga Bay); Matsubara 1955:1314 (in key; Japan); Kamohara 1958:73 (listed; Kochi Pref.); Okada et al. 1959:83 (listed; Kumano-nada); Kuroda 1962:8, fig. 2 (description of fresh color; 1 spec. from Suruga Bay); Kamohara 1964:96 (listed; Kochi Pref.); Matsubara 1965:507 (compiled; Japan); Okamura 1970a:145, pl. XXXII, text-fig. 58 (description; biological notes; 136 spec. from Pacific off Japan from Hokkaido to Mimase); Okamura 1970b: table 1 (listed; Japan); Ueno 1971:101 (listed; Hokkaido); Kataoka & Tomida 1981:78 (listed; Mie Pref.); Tominaga & Uyeno 1981:488 (listed; Japan); Shiogaki 1982:34 (listed; Aomori Pref.); Okamura 1984a:221, 364, fig. 156 [brief description; 1 spec. from Okinawa Trough; photo probably based on BSKU 22773 (from Tosa Bay)]; Okamura 1984b:95, pl. 82, fig. G (compiled); Okamura 1988:95, pl. 82, fig. G (compiled); Maeda & Maruyama 1991:366 (listed with a question mark; Hokkaido); Nakabo 1993:365 (in key; Japan); Shinohara & Matsuura 1997:290 (listed; Suruga Bay); Goto 2000:6 (3 spec. from Iwate Pref.); Nakabo 2000:429 (in key; Japan); Zama 2001:40 (listed; Miyagi Pref.); Nakabo 2002:429 (in key; Japan); Yoda et al. 2002:11 (listed; East China and Yellow Seas); Maeda & Tsutsui 2003:488 (listed; Hokkaido); Shiogaki et al. 2004:55 (listed; Pacific off Aomori Pref.); Shinohara et al. 2005:416 (listed; Ryukyu Islands); Suetsugu & Ohta 2005: table 2 (listed; southeast of Boso Peninsula); Senou et al. 2006:420 (listed; Sagami Sea); Honma et al. 2008:68, fig. 4 (brief description; 1 spec. from Niigata); Kitagawa et al. 2008:41, unnumbered fig. (brief description; spec. from Pacific off Tohoku); Shinohara et al. 2009:707 (8 spec. listed from Pacific off Tohoku); Amaoka et al. 2011:131, fig. 167 (compiled; Hokkaido); Nakabo & Kai 2013:505 (in key; Japan); Kawano et al. 2014: appendix table (listed; Sea of Japan); Shinohara et al. 2014:241 (listed; Sea of Japan); Amaoka et al. 2020:165, fig. 224 (listed; Hokkaido).

[?] Coelorhynchus kishinouyei (not Jordan & Snyder 1900): Shiogaki 1982:33 (listed; Aomori Pref.; “a large species attaining 1 m TL”).

[?] Coelorinchus kishinouyei (not Jordan & Snyder 1900): Shiogaki 1988: table 1 [listed; Pacific off Aomori Pref.; obviously after Shiogaki (1982)]; Shiogaki et al. 1992:29 [listed after Shiogaki (1982); Aomori Pref.].

Coelorinchus macrochir: Iwamoto 1990:171 , fig. 392 (synopsis); Balanov 2003:483 (first record from Okhotsk Sea; description; 1 spec.); Shao et al. 2008b: table 2 (2 spec. listed from northeastern Taiwan; first record from Taiwan); Kim et al. 2009b:110, fig. 5 (brief description; 7 spec. from Korea and Japan; new Korean record); Iwamoto et al. 2015:61, fig. 7 (brief description; 2 spec. from northeastern Taiwan); Motomura 2020:38 (listed; Japan).

Caelorinchus macrochir : Shinohara et al. 1996:169 (2 spec. listed from Pacific off Tohoku); Shinohara et al. 2001:305 (listed; Tosa Bay).

[?] Caelorinchus kishinouyei (not Jordan & Snyder 1900): Shiogaki et al. 2004:55 [listed after Shiogaki (1982); Pacific off Aomori Pref.]; Shinohara et al. 2009:708 [listed after Shiogaki (2004); Pacific off Tohoku].

Caelorinchus sp.: Matsuura et al. 2009:24 (1 spec. from Fukushima Pref.; NSMT-P 73686 ) .

Coryphaenoides sp.: Matsuura et al. 2009:24 (1 spec. from Miyagi Pref.; NSMT-P 74215 ) .

Diagnosis. Anus situated about midway between inner pelvic-fin bases and anal-fin origin. Light organ small, located immediately anterior to anus. Head fully scaled. Snout moderately long, deep, bluntly pointed, length 40–52% PRL; dorsal profile of snout convex in lateral view; tip of snout situated above horizontal through midorbit; terminal scute small, tubercular; suborbital ridge distinctly curved anteriorly; lateral nasal ridge incompletely supported by nasal bone. Premaxillary teeth small, conical, arranged in narrow band (about 3 rows), with outer series enlarged; posterior margin of tooth band extending beyond midway of rictus; mandibular teeth in 2 irregular rows, with inner series distinctly enlarged. Body scales covered with short, moderately erect, knife-like to keel-like spinules in widely divergent rows; spinules in each row overlapping, but free from one another; buttresses narrowly developed. Occipital scales covered with short, erect, needle-like spinules in widely divergent, com-like rows. Tip of pectoral fin extending well beyond vertical through anal-fin origin; pectoral-fin length 88– 104% PRL. Body darker dorsally, paler ventrally (lateral surfaces of head and body broadly silvery-white in small specimens); no prominent markings in adult (several dark bars and spots present in juveniles); fins blackish.

Material examined. 22 specimens. Holotype of Macrurus macrochir: BMNH 1887.12.7.123 (142 mm HL, 657+ mm TL), off Eno-shima Island , Kanagawa Pref., Sagami Bay , Japan , 35.1833ºN, 139.4667ºE, 345 ftm (631 m), Challenger sta. 232, trawl and dredge, 12 Mar. 1875. Non-types : Japan: BSKU 22773 (1, 97.7 mm HL, 512 mm TL), Tosa Bay , 32.9467ºN, 133.5567ºE, 714–735 m, R/ V Hakuho-maru, cr. KH-74-3, sta. B5-1, beam trawl, 24 Jul. 1974 ; * BSKU 110140 (1, 30.5 mm HL, 100+ mm TL), Suruga Bay , 34.7651ºN, 138.4880ºE, 200–450 m, F/ V Hinode-maru, sta. 4, bottom trawl, coll. N. Nakayama and R. Misawa, 23 Apr. 2013 ; KPM-NI 34639 (1, 139 mm HL, 689+ mm TL), Suruga Bay off Izu Peninsula , 710 m, coll. H. Masuda, 24 Aug. 1995 ; KPM-NI 34659 (1, 141 mm HL, 707+ mm TL), east of Futo , Sagami Bay , 700 m, F/ V Yusaku-maru, coll. H. Masuda, 11 Feb. 1997 ; * BSKU 19160 (1, 59.0 mm HL, 300+ mm TL), off Mito , 36.2717ºN, 140.9467ºE, 355–370 m, FRV Soyo-maru , sta. 18, beam trawl, 25 Jul. 1960 ; NSMT-P 78249 (5, ex. SHMNH-P 19325, 62.6–75.6 mm HL, 248+–345+ mm TL, counts and measurements taken on 2 of 5), off Arahama, coll. M. Atsumi, Apr. 1933 ; NSMT-P 73686 (1, 60.7 mm HL, 295+ mm TL), off Onahama, coll. H. Kakuda (or H. Sumida), Mar. 1932 ; NSMT-P 74215 (1, 65.7 mm HL, 324+ mm TL), off Natori, coll. T. Kikuta, 15 May 1932 ; NSMT-P 73515 (5, ex. SHMNH-P 25782, 51.8–57.8 mm HL, 248+–294+ mm TL, counts and measurements taken on 3 of 5), southeast off Onahama, coll. H. Sumida, 3 Jan. 1932 ; NSMT-P 77837 (1, 120 mm HL, 588+ 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 77846 (1, 110 mm HL, 614+ mm TL), east of Oshika Peninsula , 38.4033ºN, 142.0500ºE, 423 m, FRV Wakataka-maru, sta. E-425, bottom trawl, coll. G. Shinohara et al., 4 Nov. 2006 ; HUMZ 206465 (1, 128 mm HL, 643 mm TL), south of Tomakomai, Hokkaido, 42.1670ºN, 141.6503ºE, 725 m, T/ V Oshoro-maru, bottom trawl, coll. T. Tada and M. Ono, 29 Sept. 2009 ; HUMZ 206304 (1, 134 mm HL, 679+ mm TL), south of Tomakomai, Hokkaido, 42.1267ºN, 141.6133ºE, 650–750 m, T/ V Oshoro-maru, bottom trawl, coll. F. Tashiro and M. Ono, 29 Sept. 2009.

Counts and measurements. Based on 15 specimens (52.3–142 mm HL, 249+–707+ mm TL). Counts: first dorsal-fin rays II,9–11; pectoral-fin rays i15–i19; pelvicfin rays 7; gill rakers on first arch (outer/inner) 0/10–13, on second arch 9–11/10–12; longitudinal scales 28–35; transverse scale rows below first dorsal-fin origin 5.5–9, below first dorsal-fin midbase 5–7, below second dorsalfin origin 6–8, above anal-fin origin 21–27.

The following measurements are in % of HL, followed by those in % of PRL in parentheses: snout length 30–36 (40–52); orbit diameter 25–33 (36–47); postorbital length 38–46 (55–64); postrostral length 66– 74; orbit–preopercle distance 43–49 (62–70); suborbital width 11–13 (15–19); upper-jaw length 34–43 (50–60); length of rictus 27–34 (39–47); length of premaxillary tooth band 22–27 (31–37); preoral length 19–28 (26–41); length of terminal snout scute 2 (3); length of lateral nasal ridge 18–24 (24–36); length of suborbital ridge 88–93 (122–135); snout width 22–29 (31–42); internasal width 23–28 (32–41);interorbital width28–33 (39–49); occipital width 9–11 (12–16); body width over pectoral-fin bases 33–57 (47–81); body depth at first dorsal-fin origin 64–77 (92–112); body depth at anal-fin origin 50–70 (71–99); prepelvic length 108–124 (154–174); preanus length 132–146 (186–208); preanal length 147–164 (209–235); isthmus–pelvic distance 34–45 (51–65); isthmus–anus distance 56–72 (82–101); isthmus–anal distance 68–90 (101–130); pelvic–anal distance 32–50 (44–72); anusanal distance 13–23 (20–34); pelvic-fin length 33–44 (45–61); pectoral-fin length 61–74 (88–104); predorsal length 102–112 (143–169); height of first dorsal fin 41– 57 (59–83); length of first dorsal-fin base 21–31 (30–44); interdorsal length 39–60 (58–83); length of gill slit 15–22 (23–30); length of posterior nostril 7–9 (10–13); barbel length 4–6 (6–9); length of pyloric caecum 9 (13).

Size. Attains about 96 cm TL ( NSMT-P 463, 963+ mm TL, probably Japan).

Distribution. Restricted to the northwestern Pacific around Japan, including Taiwan and Korea. Known from the Pacific off Japan from Kushiro (144.38ºE) southward to Bungo Channel (132.06ºE), Okinawa Trough, Sea of Japan off Niigata and the Korean Peninsula, and southern Okhotsk Sea off Iturup Island, at depths of 158–830 m ( Balanov 2003; Shao et al. 2008b; Kim et al. 2009b; this study; Appendix 3-4B). The only species of Coelorinchus occurring in the Okhotsk Sea. Common off the Pacific coasts of northern Japan north of Choshi (35.74ºN; Chiba Pref.), but rare in other parts of its range.

Remarks. Coelorinchus macrochir was originally described as a species of Macrurus (= Macrourus Bloch, 1786 ) based on a large Challenger specimen collected from Sagami Bay off Eno-shima ( Fig. 68 ). For a full description see Okamura (1970a; as Abyssicola macrochir ). This is the only species of Japanese grenadiers that is widely distributed around the archipelago, including off the Pacific coasts of Japan, East China Sea, Sea of Japan, and Okhotsk Sea. Recently, Shao et al. (2008b) reported the species from the Da-xi fish market in northeastern Taiwan, and their specimens was briefly described and illustrated by Iwamoto et al. (2015:61, fig. 7). It was also recorded from the east of Korea by Kim et al. (2009b).

Relationships and comparisons. Coelorinchus macrochir is peculiar within the genus due to its unusual position of the anus. In most species of the genus, the anus abuts the anal-fin origin or is slightly separated from it by a few scale rows, whereas that of C. macrochir is located about midway along the pelvic–anal distance. It further differs from most congeners in its unique dentition: teeth arranged in narrow band in the premaxillary and two rows in the dentary (vs. moderately wide band in both jaws). Based on these features, previous authors often placed the species in a monotypic genus, Abyssicola Goode & Bean, 1896 . However, Iwamoto (1990:172) synonymized the genus with Coelorinchus (based on O. Okamura’s unpublished data). Also, recent molecular studies (Roa-Varón & Ortí 2009; Fukui et al. 2010) have shown that the species is deeply nested with a clade of Coelorinchus , further supporting their synonymy.

Coelorinchus macrochir is unlikely to belong to any groups of the genus mentioned in this study. It is most similar in general appearance to C. matamua ( McCann & McKnight, 1980) known from temperate waters in the Southern Hemisphere, but differs notably from that species in having a small dermal fossa of the light organ anterior to the anus (vs. no external evidence of light organ) and the underside of the head completely scaled (vs. broadly naked anteriorly), and in lacking a broad dark band encircling the trunk (vs. present).

Figures

FIGURE 67. Fresh specimens of Coelorinchus macrochir. (A–C) BSKU 110140, 30.5 mm HL, 100+ mm TL, Suruga Bay, Shizuoka Pref., Pacific, 200–450 m depth; (D) HUMZ 206465, 128 mm HL, 643 mm TL, south of Tomakomai, Hokkaido, Pacific, 725 m depth; (E) KPM-NI 34639, 139 mm HL, 689+ mm TL, Kanagawa Pref., Pacific. (A, D–E) Lateral views; (B) dorsal and (C) ventral views of the head and trunk. [Photos: (A–C) N. Nakayama; (D) HUMZ; (E) H. Masuda]

FIGURE 68. Holotype of Macrurus macrochir (= Coelorinchus macrochir). BMNH 1887.12.7.123, 142 mm HL, 657+ mm TL, Sagami Bay, Pacific, 631 m depth. (A) Lateral view; (B) dorsal and (C) ventral views of the head and trunk. Preserved condition. [Photos: N. Nakayama]

FIGURE 69. Scanning electron micrographs showing body scales (from the dorsum below the interdorsal space) of Coelorinchus macrochir. (A–B) BSKU 19160, 59.0 mm HL. (C–D) BSKU 22773, 97.7 mm HL. (A, C) Views from above; (B, D) oblique views. [Photos: NSMT]