Coelorinchus tokiensis (Steindachner & Döderlein, 1887)

Nakayama, Naohide, 2020, Grenadiers (Teleostei: Gadiformes: Macrouridae) of Japan and adjacent waters, a taxonomic monograph, Megataxa 3 (1), pp. 1-383 : 135-139

Coelorinchus tokiensis (Steindachner & Döderlein, 1887)

[Japanese name: Miyako-hige]

( Figs. 42 E–F, 88–90; Appendix 3-5C)

Macrurus tokiensis Steindachner & D̂derlein, 1887:283 [original description; syntype: MZS 1804 , from “ Tokio ”, but probably from Eno-shima Island, Sagami Bay ; 1 of 2 syntypes missing].

Coelorhynchus tokiensis : Jordan & Snyder 1901:120 (listed; Japan); Jordan & Gilbert in Jordan & Starks 1904:620 [after Steindachner & D̂derlein (1887)]; Jordan et al. 1913:418 (listed; Japan; new Japanese name: “Miyako-hige”); Gilbert & Hubbs 1916:179 (description; 2 spec. from East China Sea); Okada & Matsubara 1938:450 (in key; Japan); Kamohara 1938:73 (spec. from Kochi Pref.); Kamohara 1950:277 (listed; Kochi and Wakayama Pref.); Uchinomi 1951:76 (listed; southern part of Kii Peninsula); Kamohara 1952:100 (spec. from Kochi Pref.); Matsubara 1955:1313 (in key; Japan); Kamohara 1958:73 (listed; Kochi Pref.); Kamohara 1964:96 (listed; Kochi Pref.); Okamura 1970a:194, pl. XLII, textfig. 83 (description; 5 spec. from Pacific off southern Japan from Sagami Bay to Mimase); Tominaga & Uyeno 1981:488 (listed; Japan).

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

Coelorhynchus longicephalus Okamura, 1982:177 , fig. 105 (original description; holotype: BSKU 26144 , from Kyushu-Palau Ridge , 27º54.2ʹN, 134º39.5ʹE, in 700 m; 16 paratypes from Kyushu-Palau Ridge, in 336–700 m; new Japanese name: “Zunaga-sokodara”; in part, BSKU 26102 is C. gilberti ).

Coelorinchus tokiensis: Yatou 1984:235 , 370, fig. 168 (brief description; 5 spec. from Okinawa Trough; photo based on BSKU 29872); Okamura 1984b:97, pl. 83, fig. H (compiled); Okamura 1988:97, pl. 83, fig. H (compiled); Suzuki & Kataoka 1997:84, pl. 33, fig. 183 (brief description; 1 spec. from Kumano-nada off Namikiri); Okamura 1997:127, fig. 17 (compiled); Amaoka 2007: fig. 2-B (photograph of type specimen); Nakabo & Kai 2013:511 (in key; Japan); Nakayama et al. 2015c:249, figs. 1–7 (redescription; 59 spec. from Japan; C. hexafasciatus a junior synonym of C. tokiensis ); Miyazaki et al. 2019: fig. 3D, table1 (1 spec. listed from Tokyo Submarine Canyon); Motomura 2020:38 (listed; Japan).

Coelorinchus longicephalus: Okamura 1984b:97 , pl. 83, fig. I (compiled); Okamura 1988:97, pl. 83, fig. I (compiled); Iwamoto 1990:169, fig. 390 (synopsis); Okamura 1997:127, fig. 18 (compiled); Nakabo & Kai 2013:512 (in key; Japan); Ikeda & Nakabo 2015:322, pl. 69, figs. 6–9 (brief description; 2 spec. from Wakayama Pref.).

Caelorinchus tokiensis: Nakabo 1993:370 (in key; Japan); Miya et al. 1995: table 2 (questionable; 1 spec. from off Boso Peninsula; midwater capture); Nakabo 2000:434 (in key; Japan); Shinohara et al. 2001:305 (listed; Tosa Bay); Nakabo 2002:434 (in key; Japan); Yoda et al. 2002:11 (listed; East China and Yellow Seas); Shinohara et al. 2005:417 (listed; Ryukyu Islands); Senou et al. 2006:420 (listed; Sagami Sea).

Caelorinchus longicephalus: Nakabo 1993:371 (in key; Japan); Nakabo 2000:435 (in key; Japan); Nakabo 2002:435 (in key; Japan); Furuhashi et al. 2010: table 2 (6 spec. listed from northern Okinawa Trough ).

Diagnosis. Light organ externally represented by short, narrow, naked streak immediately anterior to anus, its anterior margin falling far short of line connecting inner pelvic-fin bases. Underside of head completely naked except for oval scaly patches on ventral surfaces of preopercles; longitudinal naked clefts along each side of mid rostral ridge scarcely developed. Snout long with bluntly pointed tip, length 70–85% PRL, its dorsal profile straight to gently convex in lateral view; snout tipped with 3 bluntly pointed scutes; lateral nasal ridge incompletely supported by nasal bone. Anus slightly separated from anal-fin origin. Premaxillary teeth in long, tapered band, with outer series prominently enlarged; posterior margin of tooth band almost reaching lateral corner of mouth. Body scales covered with short, reclined, keel-like spinules in widely divergent, fine saw-toothed ridges; every spinule row complete, extending to posterior scale margin; spinules in each row overlapping but free at tips, gradually increasing in height posteriorly; buttresses poorly developed. Occipital scales usually covered with single row of spinules. Preoral length 47–69% PRL; barbel length 9–19% PRL. About 6–7 dark saddles on body (faint in large individuals); underside of head dusky; lips white; oral cavity blackish; gular and branchiostegal membranes dusky.

Material examined. 57 specimens. Syntype of Macrurus tokiensis: MZS Pis1804 (1, 173 mm HL, 589+ mm TL), Tokyo , Japan, coll. L. D̂derlein, date unknown (examined by Nakayama et al. 2015c) . Holotype of Coelorhynchus longicephalus: BSKU 26144 (252 mm HL, 875+ mm TL), Kyushu-Palau Ridge, Japan , 27.9167ºN, 134.6500ºE, 700 m, F/ Vs Shinsei-maru, No. 53 and Kyoyo-maru, No. 2, sta. 2-3, bottom trawl, coll. Y. Kobayashi et al., 20 Feb. 1978 . Paratypes of C. longicephalus: BSKU 29535 (1, 122 mm HL, 453 mm TL), BSKU 29536 (1, 208 mm HL, 680+ mm TL), Kyushu-Palau Ridge , 27.7500ºN, 135.3167ºE, 336 m, F/ Vs Shinsei-maru, No. 53 and Kyoyo-maru, No. 2, sta. T19, bottom trawl, coll. Y. Kobayashi et al., 17 Dec. 1979 ; BSKU 30438 (1, 127 mm HL, 459 mm TL) , BSKU 30439 (1, 252 mm HL, 870+ mm TL) , BSKU 30444 (1, 197 mm HL, 685+ mm TL), Kyushu-Palau Ridge , 26.7500ºN, 135.3167ºE, 336 m, F/ Vs Shinsei-maru, No. 53 and Kyoyo-maru, No. 2, sta. T8, bottom trawl, coll. Y. Kobayashi et al., 17 Dec. 1979 ; BSKU 32223 (1, 113 mm HL, 363+ mm TL), Kyushu-Palau Ridge , 28.1117ºN, 134.6656ºE, 550–600 m, F/ Vs Shinsei-maru, No. 53 and Kyoyo-maru, No. 2, tr. 9, bottom trawl, coll. O. Okamura et al., 19 Dec. 1979 ; BSKU 29435 (1, 127 mm HL, 363+ mm TL), Kyushu-Palau Ridge , 28.1070ºN, 134.6593ºE, 550–600 m, F/ Vs Shinsei-maru, No. 53 and Kyoyomaru, No. 2, sta. 4-T9, bottom trawl, coll. O. Okamura et al., 19 Dec. 1979 ; BSKU 26222 (1, 227 mm HL, 755+ mm TL) , BSKU 26223 (1, 197 mm HL, 634+ mm TL), Kyushu-Palau Ridge , 27.9000ºN, 134.6550ºE, 695 m, F/ Vs Shinsei-maru, No. 53 and Kyoyo-maru, No. 2, sta. 2- 2, bottom trawl, coll. Y. Kobayashi et al., 15 Feb. 1978 ; BSKU 26100 (1, 198 mm HL, 659+ mm TL) , BSKU 26101 (1, 227 mm HL, 779+ mm TL) , BSKU 26103 (1, 211 mm HL, 742+ mm TL) , BSKU 26104 (1, 202 mm HL, 672+ mm TL) , BSKU 26145 (1, 229 mm HL, 784+ mm TL) , BSKU 26146 (1, 167 mm HL, 514+ mm TL), collected with holotype. Non-types : Japan: KPM-NI 24973 (1, 240 mm HL, 878 mm TL), near Okinawa, 600 m, long line, coll. K. Yunokawa, 2009 ; BSKU 106833 (1, 55.3 mm HL, 190+ mm TL) , BSKU 106834 (1, 73.8 mm HL, 266 mm TL), southeast of Shimokoshiki-jima Island, East China Sea , 31.5675ºN, 129.8930ºE, 393 m, F/ V Maruko-maru, tr. 2, bottom trawl, coll. N. Nakayama et al., 24 Apr. 2012 ; BSKU 106825 (1, 53.3 mm HL, 175+ mm TL), southeast of Shimokoshiki-jima Island, East China Sea , 31.5658ºN, 129.8915ºE, 380 m, F/ V Marukomaru, tr. 1, bottom trawl, coll. N. Nakayama et al., 24 Apr. 2012 ; BSKU 106815 (1, 60.8 mm HL, 215 mm TL), southeast of Shimokoshiki-jima Island, East China Sea , 31.5652ºN, 129.8878ºE, 407 m, F/ V Maruko-maru, tr. 3, bottom trawl, coll. N. Nakayama et al., 24 Apr. 2012 ; BSKU 106773 (1, 69.6 mm HL, 228+ mm TL) , BSKU 106774 (1, 59.8 mm HL, 204+ mm TL) , BSKU 106781 (1, 80.5 mm HL, 289+ mm TL) , BSKU 106782 (1, 75.5 mm HL, 268+ mm TL) , BSKU 106783 (1, 70.1 mm HL, 250 mm TL) , BSKU 106784 (1, 71.5 mm HL, 262 mm TL) , BSKU 106785 (1, 74.6 mm HL, 263+ mm TL) , BSKU 106786 (1, 67.1 mm HL, 238+ mm TL) , BSKU 106787 (1, 67.1 mm HL, 236+ mm TL) , BSKU 106788 (1, 74.6 mm HL, 263 mm TL), southeast of Shimokoshiki-jima Island, East China Sea , 31.5560ºN, 129.8847ºE, 415 m, F/ V Maruko-maru, tr. 4, bottom trawl, coll. N. Nakayama et al., 24 Apr. 2012 ; FFNU P-00630 (1, 73.1 mm HL, 249 mm TL), west of Amakusa Knoll, East China Sea , 32.1465ºN, 129.4870ºE, 511 m, T/ V Nagasaki-maru, cr. N211, sta. B5-4, 3-m ORE beam trawl, coll. J. Hashimoto, 10 May 2006 ; FFNU P-00642 (1, 84.8 mm HL, 300 mm TL), east of Hirazi Bank, East China Sea , 32.2440ºN, 129.4802ºE, 421 m, T/ V Nagasaki-maru, cr. N224, sta. B4, 3-m ORE beam trawl, coll. J. Hashimoto, 28 Oct. 2006 ; BSKU 29872 (1, 129 mm HL, 472+ mm TL), east of Danjo Islands, Okinawa Trough , 32.0033ºN, 128.7050ºE, 360–400 m, F/ V Yuryo-maru, No. 8, sta. 3-L18, long line, coll. H. Maeda, 2 Nov. 1979 ; FFNU P-00672 (1, 140 mm HL, 521 mm TL), northwest of Daiichi-Danjo Knoll, East China Sea , 31.7013ºN, 128.5800ºE, 500 m, T/ V Nagasaki-maru, cr. N237, sta. E5-2, 3-m ORE beam trawl, coll. J. Hashimoto, 9 May 2007 ; HUMZ 95252 (1, 241 mm HL, 877+ mm TL), northwest of Amami-oshima, East China Sea , 28.9817ºN, 128.0233ºE, 760–790 m, hook and line, 14 Nov. 1981 ; BSKU 28710 (1, 205 mm HL, 760 mm TL), northwest of Amami-oshima Island, Okinawa Trough , 29.7333ºN, 127.8000ºE, 495–510 m, F/ V Ryoan-maru, No. 28, tr. 72, bottom trawl, coll. Y. Kinoshita and S. Hagino, 19 Mar. 1978 ; BSKU 33258 (1, 150 mm HL, 549+ mm TL), northwest of Amami-oshima Island, Okinawa Trough , 29.7167ºN, 127.7000ºE, 520 m, F/ V Yuryo-maru, No. 8, sta. 2-T12, bottom trawl, coll. M. Hirose and T. Kume, 14 Oct. 1979 ; BSKU 27223 (1, 165 mm HL, 600 mm TL), northwest of Amami-oshima Island, Okinawa Trough , 29.4333ºN, 127.5167ºE, 570 m, F/ V Yuryo-maru, No. 8, tr. 22, bottom trawl, coll. Y. Kinoshita and S. Hagino, 5 Feb. 1978 ; BSKU 27140 (1, 82.8 mm HL, 290 mm TL), northwest of Amami-oshima Island, Okinawa Trough , 29.3833ºN, 127.5150ºE, 650 m, F/ V Yuryo-maru, No. 8, tr. 21, bottom trawl, coll. Y. Kinoshita and S. Hagino, 5 Feb. 1978 ; BSKU 27584 (1, 55.2 mm HL, 198+ mm TL), northwest of Amami-oshima Island, Okinawa Trough , 28.7167ºN, 127.2333ºE, 750– 755 m, F/ V Ryoan-maru, No. 28, tr. 48, bottom trawl, coll. Y. Kinoshita and S. Hagino, 11 Mar. 1978 ; BSKU 44426 (1, 194 mm HL, 746+ mm TL) , BSKU 44427 (1, 152 mm HL, 514+ mm TL), off Nahari, Tosa Bay , 300 m, 13 Jan. 1988 ; BSKU 44361 (1, 231 mm HL, 820+ mm TL) , BSKU 44362 (1, 190 mm HL, 641+ mm TL), off Yasuda, Tosa Bay , 400 m, 9 Dec. 1987 ; BSKU 43855 (1, 245 mm HL, 824+ mm TL), off Kochi, 11 Jul. 1987 ; BSKU 81498 (1, 53.4 mm HL, 197 mm TL), Tosa Bay , 600 m, FRV Kotaka-maru, otter trawl, 16 May 1988 ; BSKU 45506 (1, 194 mm HL, 690+ mm TL), off Tosa-Shimizu, long line, 24 Aug. 1988 ; BSKU 45500 (1, 269 mm HL, 879+ mm TL) , BSKU 45501 (1, 251 mm HL, 901+ mm TL) , BSKU 45503 (1, 245 mm HL, 898 mm TL), off Tosa-Shimizu, long line, Oct. 1988 ; MSM 10-8 (1, 217 mm HL, 833+ mm TL), Numazu fish market, date unknown ; FRLM 3578 (1, 165 mm HL, 573 mm TL), off Mie, Kumanonada , long line, coll. Fisheries Research Institute of Mie Pref., 25 May 1982 ; NSMT-P 100178 (1, 67.7 mm HL, 226+ mm TL), northeast of Miyake-jima Island, Shichito-Iojima Ridge , 34.1287ºN, 139.6413ºE, 484–565 m, R/ V Tansei-maru, cr. KT-89-06, sta. ME10, 3-m ORE beam trawl, 19 May 1989 ; FAKU 34265 (1, 139 mm HL, 478+ mm TL), off Oiso, Sagami Bay , Apr. 1969 ; FAKU 35862 (1, 111 mm HL, 366+ mm TL), Sagami Bay , Apr. 1962 .

Counts and measurements. Based on 57 specimens (53.3–269 mm HL, 175+–901+ mm TL). Counts: first dorsal-fin rays II,8–10; pectoral-fin rays i16–i19; pelvicfin rays 6–7; gill rakers on first arch (outer/inner) 0–2/8– 11, on second arch 7–9/9–11; longitudinal scales 37–53; transverse scale rows below first dorsal-fin origin 5.5–9, below first dorsal-fin midbase 4.5–7, below second dorsal-fin origin 5.5–8, above anal-fin origin 18.5–28.5; pyloric caeca 51–61.

The following measurements are in % of HL, followed by those in % of PRL in parentheses: snout length 42–46 (70–85); orbit diameter 20–27 (36–46); postorbital length 31–36 (54–65); postrostral length 54– 59; orbit–preopercle distance 33–40 (58–72); suborbital width 10–13 (18–22); upper-jaw length 25–31 (44–57); length of rictus 19–25 (34–45); length of premaxillary tooth band 16–22 (29–38); preoral length 26–39 (47–69); length of terminal snout scute 18 (33); length of lateral nasal ridge 24–28 (40–51); length of suborbital ridge 92–98 (162–178); snout width 20–27 (35–48); internasal width 16–20 (28–34); interorbital width 18–23 (32–39); occipital width 6–9 (11–16); body width over pectoral-fin bases 32–46 (56–82); body depth at first dorsal-fin origin 42–57 (74–102); body depth at anal-fin origin 35–50 (60– 90); prepelvic length 99–115 (172–205); preanus length 122–147 (209–265); preanal length 128–155 (220–277); isthmus–pelvic distance 22–33 (39–59); isthmus–anus distance 49–63 (85–112); isthmus–anal distance 51–74 (88–131); pelvic–anal distance 26–44 (46–78); anus–anal distance 4–10 (8–17); pelvic-fin length 25–45 (44–78); pectoral-fin length 32–46 (54–78); predorsal length 102– 109 (178–196); height of first dorsal fin 35–43 (62–74); length of first dorsal-fin base 15–20 (26–35); interdorsal length 10–24 (17–43); length of gill slit 14–18 (24–31); length of posterior nostril 6–9 (11–16); barbel length 5–11 (9–19); length of pyloric caecum 3–5 (6–8).

Size. Attains about 90 cm TL (BSKU 45501, 901+ mm TL, off Tosa-Shimizu, Kochi, Japan).

Distribution. In Japan, known from the Pacific off southern Japan northward to the Boso Peninsula (139.89ºE), off the Izu Islands, the Okinawa Trough, and the Kyushu-Palau Ridge, at depths of 300‾ 790 m (Appendix 3-5C). Elsewhere, known only from the South China Sea (Iwamoto in Randall & Lim 2000). Common in the northern Okinawa Trough and Kyushu-Palau Ridge, but rare in other parts of its range.

Remarks. Coelorinchus tokiensis was originally described as a species of Macrurus (= Macrourus Bloch, 1786 ) on the basis of two specimens collected from Tokyo, Japan (probably originally from off Eno-shima Island, Sagami Bay; see Amaoka 2007:28). One of the two syntypes was recently found among the ichthyological collection of the Musée Zoologique de l’Université Louis Pasteur, Strasbourg (MZS Pis1804; Amaoka 2007: fig. 2b; Fig. 89 ). Nakayama et al. (2015c) redescribed C. tokiensis with an examination of the MZS syntype, and recognized C. longicephalus Okamura, 1982 ( Fig. 90 ) as a junior synonym of the former.

Relationships and comparisons. Coelorinchus tokiensis is one of six species of the C. tokiensis group as redefined by Nakayama et al. (2015c; see the Relationships of C. hexafasciatus ), and is readily distinguished from its similar congeners by having the combination of a long snout (70–85% PRL) and the underside of the head completely naked except for oval scaly patches on the ventral surfaces of the preopercles.

Figures

FIGURE 42. Scanning electron micrographs showing body scales (from the dorsum below the interdorsal space) of three species of the Coelorinchus tokiensis group. (A–B) C. hexafasciatus, BSKU 29452, paratype, 167 mm HL; (C–D) C. sheni, CAS 215541, 112 mm HL; (E–F) C. tokiensis, BSKU 26104, paratype of C. longicephalus, 202 mm HL. (A, C, E) Views from above; (B, D, F) oblique views. [Photos: (A–B, E–F) N. Nakayama; (C–D) NSMT]

FIGURE 89. Syntype of Macrurus tokiensis (= Coelorinchus tokiensis). MZS Pis1804, 173 mm HL, 589+ mm TL, Tokyo, Pacific. (A) Dorsal and (B) ventral views of the head and trunk; (C) lateral view. Preserved condition. [Photos: reproduced from Nakayama et al. (2015c: fig. 1) with permission from the Ichthyological Society of Japan]

FIGURE 90. Preserved specimen of Coelorinchus tokiensis. BSKU 26144, holotype of Coelorhynchus longicephalus, 252 mm HL, 875+ mm TL, Kyushu-Palau Ridge, Pacific, 700 m depth. (A) Lateral view; (B) dorsal and (C) ventral views of the head and trunk. Preserved condition. [Photos: reproduced from Nakayama et al. (2015c: fig. 2) with permission from the Ichthyological Society of Japan]