Coelorinchus cingulatus Gilbert & Hubbs, 1920

Nakayama, Naohide, 2020, Grenadiers (Teleostei: Gadiformes: Macrouridae) of Japan and adjacent waters, a taxonomic monograph, Megataxa 3 (1), pp. 1-383 : 42-44

Coelorinchus cingulatus Gilbert & Hubbs, 1920

[Japanese name: Kurakake-sokodara]

( Figs. 28 C–D, 29; Appendix 3-1E)

Coelorhynchus cingulatus Gilbert & Hubbs, 1920:480 , fig. 15 [original description; holotype: USNM 78221, from “ China Sea near Taiwan ”, Albatross sta. 5317, in 230 ftm (421 m); 1 paratype from “ China Sea off northern Luzon”]; Chen 1951:210 (listed; Taiwan).

Coelorinchus cingulatus: Okamura 1984a:229 , 366, fig. 161 (first record from Japan; brief description; 1 spec. from Okinawa Trough; BSKU 28658; new Japanese name: “Kurakakesokodara”); Okamura 1988:453, pl. 373, fig. H (compiled); Shao et al. 2008b: table 2 (17 spec. listed from northeastern and southwestern Taiwan, and South China Sea); Ho & Shao 2011:36 (type catalog); Nakabo & Kai 2013:508 (in key; Japan); Iwamoto et al. 2015:52 (brief description; 29 spec. from northeastern and southwestern Taiwan, and Philippines); Motomura 2020:38 (listed; Japan).

Caelorinchus cingulatus: Nakabo 1993:367 (in key; Japan); Shao 1993:168 (compiled; Taiwan); Nakabo 2000:431 (in key; Japan); Nakabo 2002:431 (in key; Japan); Yoda et al. 2002:11 (listed; East China and Yellow Seas); Shinohara et al. 2005:416 (listed; Ryukyu Islands).

Caelorinchus dorsalis (not Gilbert & Hubbs 1920): Shao 1993:168 (compiled; Taiwan) [fide Chiou et al. (2004a: table1)].

Caelorinchus (Paramacrurus) cinguletus [sic]: Chiou et al. 2004a: table 1 (listed; Taiwan).

Diagnosis. Ventral light organ externally represented by long dark line, terminated with 1 fossa at each end, one immediately anterior to anus, the other on chest just posterior to isthmus (duct connecting each fossa often difficult to distinguish). Underside of head completely naked except along lateral nasal ridges; dorsal surface of snout almost fully scaled, naked clefts only narrowly developed along each side of median rostral ridge. Snout long, sharply pointed, length 79–86% PRL; dorsal profile of snout distinctly concave in lateral view; terminal scute long, slender, spearhead-shaped, length 20–26% PRL; distal portion of snout narrowly attenuated when viewed dorsally; lateral nasal ridge incompletely supported by nasal bone. Interdorsal space less than first dorsal-fin base length. Anal fin originating posterior to vertical through second dorsal-fin origin. Second spinous ray of first dorsal fin greatly elongate, height of fin 123–156% PRL in adults. Second dorsal fin well developed, its rays as long as opposites of anal fin. Anus immediately anterior to anal-fin origin. Premaxillary teeth small, slender, conical 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 short, reclined, needle-like spinules in subparallel to slightly divergent rows; spinules in each row overlapping, but free from one another, with last spinule extending well beyond posterior scale margin; buttresses scarcely developed. Spinules on scales anterior to light organ not rudimentary. Orbit diameter 41–47% PRL; postorbital length 54–61% PRL; upper-jaw length 35–43% PRL; preoral length 66–80% PRL; barbel length 10–13% PRL. Transverse scale rows below first dorsal-fin midbase 4–5.5. Body with several dark markings including prominent diagonal stripes on trunk and faint elongate blotches on anterior portion of tail; longitudinal dark stripe running along lower margin of postorbital canal; scale pockets on dorsal half of body outlined by dark brown; underside of head dusky, heavily peppered; lips pale; oral cavity blackish; gular and branchiostegal membranes dusky to dark; first dorsal fin uniformly dark, but second spinous ray paler; pelvic fin dark, but outermost ray paler distally.

Material examined. 13 specimens. Holotype of Coelorhynchus cingulatus: USNM 78221 (40.0 mm HL, 127+ mm TL), northern South China Sea , 21.6000ºN, 117.4500ºE, 230 ftm (421 m), Albatross sta. 5317, 12- ft Tanner beam trawl, 5 Nov. 1908 . Paratype of C. cingulatus: USNM 78233 (1, 41.2 mm HL, 146+ mm TL), South China Sea off northern Luzon, Hermanos Island , Philippines , 18.5708ºN, 121.8542ºE, 224 ftm (410 m), Albatross sta. 5325, 12-ft Tanner beam trawl, 12 Nov. 1908 . Non-types: Japan: BSKU 28658 (1, 60.6 mm HL, 232 mm TL), northwest of Amami-oshima Island, Okinawa Trough , 29.9000ºN, 127.7167ºE, 250 m, F/ V Ryoan-maru, No. 28, tr. 78, bottom trawl, coll. Y. Kinoshita and S. Hagino, 21 Mar. 1978 ; FAKU 204486 (1, 28.2 mm HL, 105+ mm TL), Mimase fish market, F/ V Tsukasa-maru, bottom trawl, coll. N. Nakayama 4 Mar. 2017 , bottom trawl. Taiwan: KAUM-I. 44654 (1, 67.8 mm HL, 224+ mm TL), off Kaohsiung, Pingtung, 400 m, trawl, coll. M. Matsunuma and H.-C. Ho, 1 Jul. 2011 ; BSKU 98963 (1, 60.4 mm HL, 191+ mm TL), BSKU 98964 (1, 34.8 mm HL, 122+ mm TL), Dong-gang fish market, Pingtung, bottom trawl, coll. H.-C. Ho, 16 Nov. 2007 ; * FAKU 204447 (1, 45.3 mm HL, 179+ mm TL), Dong-gang fish market, Pingtung, bottom trawl, coll. N. Nakayama, 27 Feb. 2017 . South China Sea: BSKU 106847 (1, 62.8 mm HL, 224+ mm TL), BSKU 106848 (1, 60.6 mm HL, 232+ mm TL), off Swatow , 21.6867ºN, 117.5183ºE, 415–437 m, R/ V Hakuho-maru, cr. KH-73- 02, sta. 44-1, 3-m beam trawl, 19 Mar. 1973 . Philippines: ASIZP 68017 (1, 59.0 mm HL, 227+ mm TL), east of Luzon Island , 14.7665ºN, 123.6553ºE, 356–367 m, French type beam trawl, coll. Y.-C. Liao and K.-T. Shao, 26 May 2007 ; ASIZP 67859 (1, 61.0 mm HL, 227+ mm TL), east of Luzon Island , 15.9908ºN, 121.8447ºE, 422–431 m, French type beam trawl, coll. Y.-C. Liao and K.-T. Shao, 20 May 2007 ; ASIZP 68394 (1 of 2, 61.3 mm HL, 211+ mm TL), east of Luzon Island , 15.9908ºN, 121.8447ºE, 422–431 m, French type beam trawl, coll. Y.-C. Liao and K.-T. Shao, 20 May 2007 .

Counts and measurements. Based on 12 specimens (28.2–67.8 mm HL, 105+–232+ mm TL). Counts: first dorsal-fin rays II,8–9; pectoral-fin rays i16–i20; pelvic-fin rays 7; gill rakers on first arch (outer/inner) 0/7, on second arch 5–6/7–9; longitudinal scales 31–37; transverse scale rows below first dorsal-fin origin 5.5–6.5, below first dorsal-fin midbase 4–5.5, below second dorsal-fin origin 4–6, above anal-fin origin 13.5–16.5.

The following measurements are in % of HL, followed by those in % of PRL in parentheses: snout length 44–46 (79–86); orbit diameter 22–27 (41–47); postorbital length 30–34 (54–61); postrostral length 54– 57; orbit–preopercle distance 29–34 (53–60); suborbital width 11–15 (21–27); upper-jaw length 19–24 (35–43); length of rictus 14–19 (26–34); length of premaxillary tooth band 7–9 (13–17); preoral length 37–44 (66–80); length of terminal snout scute 11–14 (20–26); length of lateral nasal ridge 31–34 (55–63); length of suborbital ridge 90–96 (160–174); snout width 25–31 (44–57); internasal width 17–20 (30–37); interorbital width 20–21 (35–38); occipital width 8–10 (15–19); body width over pectoral-fin bases 31–45 (56–82); body depth at first dorsal-fin origin 39–52 (71–93); body depth at anal-fin origin 32–41 (58–74); prepelvic length 101–117 (183– 212); preanus length 135–154 (245–276); preanal length 139–161 (252–292); isthmus–pelvic distance 24–32 (44– 58); isthmus–anus distance 62–75 (111–134); isthmusanal distance 64–80 (116–142); pelvic–anal distance 42–53 (75–95); anus–anal distance 3–8 (5–15); pelvic-fin length 33–39 (61–70); pectoral-fin length 32–45 (57–83); predorsal length 104–109 (186–199); height of first dorsal fin 59–85 (107–156); length of first dorsal-fin base 16–18 (27–32); interdorsal length 4–12 (8–22); length of gill slit 10–13 (18–24); length of posterior nostril 8–11 (15–20); barbel length 5–7 (10–13).

Size. To about 23 cm TL ( BSKU 28658, 232 mm TL, Okinawa Trough , Japan) .

Distribution. Known from Tosa Bay and the East and South China Seas at depths of 250–1211 m ( Gilbert & Hubbs 1920; Shao et al. 2008a, 2008b; this study; Appendix 3-1E). Very rare in Japanese waters.

Remarks. Coelorinchus cingulatus was originally described from the northern South China Sea by Gilbert & Hubbs (1920), to which the reader can refer for further morphological details. This species was first reported from Japanese waters by Okamura (1984a) based on a single specimen collected from the Okinawa Trough (BSKU 28658).

Iwamoto & Merrett (1997) and Merrett & Iwamoto (2000) recorded this species from the New Caledonian region and off the east coast of Australia. However, Iwamoto& Graham (2001:442) subsequently re-identified these specimens as Coelorinchus sp. cf. cingulatus , noting that “… their specimens, though closely similar, did not entirely agree with the description of C. cingulatus Gilbert & Hubbs, 1920 , especially in regards to certain body markings …” A further study is therefore necessary to elucidate the taxonomic status of the southwestern Pacific population.

Comparisons. Coelorinchus cingulatus is a distinctive species of the C. hubbsi group (see the Relationships of C. brevirostris ). Its body markings, consisting of somewhat broken, diagonal bands or stripes, readily diagnose the species from other members of this group. Similar markings are also found in C. cylindricus Iwamoto & Merrett, 1997 known from the Norfolk Ridge and New Zealand, C. fuscigulus Iwamoto, Ho & Shao, 2009 from the East China Sea, C. melanosagmatus Iwamoto & Anderson, 1999 from the Indian Ocean, and C. multifasciatus Sazonov & Iwamoto, 1992 from the Sala y Gomez Ridge; however, their markings consist of regularly arranged distinct saddles. It further differs from all except C. brevirostris Okamura, 1984 in that the second spinous ray of the first dorsal fin is distinctly elongate in adult specimens [height of first dorsal fin 123–156% PRL (107% in a 28.2 mm HL spec.; FAKU 204486) vs. not elongate, usually ±122%]. Coelorinchus hubbsi Matsubara, 1936 also has a high first dorsal fin (85–130% PRL, usually ±122%), but its second spinous ray is not especially elongated.

Figures

FIGURE 28. Scanning electron micrographs showing body scales of three species of the Coelorinchus hubbsi group. (A–B) C. brevirostris, FFNU P-640, 52.6 mm HL; (C–D) C. cingulatus, BSKU 98963, 60.4 mm HL; (E–F) C. fuscigulus, BSKU 106760, 41.9 mm HL. (A, C, E) Scales from the dorsum below the interdorsal space; (B, D, F) from the chest between the isthmus and the anterior tip of the light organ. Views from above. [Photos: N. Nakayama]