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.