Coelorinchus parallelus (Günther, 1877)

Nakayama, Naohide, 2020, Grenadiers (Teleostei: Gadiformes: Macrouridae) of Japan and adjacent waters, a taxonomic monograph, Megataxa 3 (1), pp. 1-383 : 119-126

Coelorinchus parallelus (Günther, 1877)

[Japanese name: Soroi-hige]

( Figs. 31 C–F, 79–81; Table 4 ; Appendix 3-4F)

Macrurus parallelus G̹nther, 1877:439 [original description; in part; lectotype: BMNH 1887.12 .7.65 (designated herein), from “off Inoshima” (= Eno-shima Island), Challenger sta. 232, in 345 ftm (631 m); paralectotypes. in BMNH, MNHN, NMI; see the Comments on type specimens]; G̹nther 1887:125, pl. XXIX, figs. A, Aʹ, Aʺ, a, aʹ, aʺ, a‴ (description; in part, BMNH 1887.12.7.65–66, 2 spec., from Sagami Bay off Eno-shima Island ); Wheeler & O’Riordan 1969:95 (comments on type specimens) .

Coelorhynchus parallelus : Jordan & Gilbert in Jordan & Starks 1904:618 (description; 1 spec. from Misaki); Franz 1910:26 (3 spec. from Aburatsubo); Jordan et al. 1913:418 (listed; Japan; new Japanese name: “Soroi-hige”); Gilbert & Hubbs 1916:181 (brief description; 4 spec. from East China Sea); Kamohara 1931a:95 (questionable; listed; Kochi); Kamohara 1934a:54 (questionable; listed; Kochi); Okada & Matsubara 1938:451 (in key; Japan); Kamohara 1938:73 (questionable; spec. from Kochi Pref.); Kamohara 1950:276 (questionable; listed; Kochi and Wakayama Pref.); Uchinomi 1951:76 (questionable; listed; southern part of Kii Peninsula); Kamohara 1952:99 (questionable; spec. from Kochi Pref.); Matsubara 1955:1313 (in key; Japan); Kamohara 1958:73 (questionable; listed; Kochi Pref.); Kamohara 1964:96 (questionable; listed; Kochi Pref.); Okamura 1970a:198, pl. XLIII, text-fig. 86 (description; 2 spec. from Sagami Bay and East China Sea; erroneously considered type locality New Zealand); Tominaga & Uyeno 1981:488 (listed; Japan).

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

Coelorinchus sparsilepis Okamura & Yatou, 1984:241 , fig. 170 (original description; holotype: BSKU 28441, from Okinawa Trough, 29º46.0ʹN, 127º59.0ʹE, in 710–713 m; new Japanese name: “Mabara-hige”); Okamura 1988:453, pl. 373, fig. K (compiled); Nakabo & Kai 2013:509 (in key; Japan); Motomura 2020:38 (listed; Japan).

Coelorinchus parallelus: Yatou 1984:245 , 370, fig. 171 (brief description; 9 spec. from Okinawa Trough; photo based on BSKU 29896); Okamura 1984b:97, pl. 83, fig. I (compiled); Okamura 1988:97, pl.83, fig.I (compiled); Iwamoto 1990:178, fig. 404 (synopsis); Okamura 1997:127, fig. 20 (compiled); Shao et al. 2008b: table 2 (3 spec. listed from southwestern Taiwan); Nakabo & Kai 2013:509 (in key; Japan); Iwamoto et al. 2015:65 (brief description; 6 spec. from northeastern and southwestern Taiwan, and South China Sea); Motomura 2020:38 (listed; Japan).

Caelorinchus parallelus: Nakabo 1993:369 (in key; Japan); Shao 1993:170 (compiled; Taiwan); Shinohara & Matsuura 1997:291 (listed; Suruga Bay); Nakabo 2000:433 (in key; Japan); Shinohara et al. 2001:304 (2 spec. listed from Tosa Bay); Nakabo 2002:433 (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 sparsilepis: Nakabo 1993:369 (in key; Japan); Nakabo 2000:433 (in key; Japan); Nakabo 2002:433 (in key; Japan); Yoda et al. 2002:11 (listed; East China and Yellow Seas); Shinohara et al. 2005:417 (listed; Ryukyu Islands).

Caelorinchus (Oxygadus) parallelus: Chiou et al. 2004a : table 1 (listed; Taiwan).

Coelorinchus commutabilis (not Smith & Radcliffe in Radcliffe 1912): Shao et al. 2008b: table 2 [2 spec. listed from South China Sea (as first record from Taiwan)].

Diagnosis. No external evidence of light organ anterior to anus. Underside of head, including ventral surfaces of preopercles, completely and uniformly scaled except for anterior portions of mandibular rami; dorsal surface of snout fully scaled; nasal fossa usually heavily scaled anteroventrally. Snout long, sharply pointed, length 67–89% PRL; dorsal profile of snout almost straight to slightly concave in lateral view; terminal scute moderately long, 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 margin of tooth band falling far short of lateral corner of mouth. Body scales covered with stout, broadly trihedral, shield-like spinules in parallel ridge-like rows; middle row notably enlarged and higher, giving striated appearance to body surface; lateral rows often incomplete, not extending to posterior scale margin; lateral buttresses broadly developed. Transverse scale rows below first dorsal-fin origin 4.5–7. Occipital scales covered with single crest-like row of short, keel-like spinules; no prominent naked area atop head between parietal ridges. Modified scales on head ridges prominently spiny and thickened. Free neuromasts on underside of head not especially enlarged. Height of first dorsal fin 48–77% PRL. Head and body uniformly dark brown; orbit narrowly edged in black; all fins blackish.

Material examined. 48 specimens. Lectotype of Macrurus parallelus (designated herein): BMNH 1887.12 .7.65 (93.2 mm HL, 325+ 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 . Paralectotype of M. parallelus (designated herein): BMNH 1887.12 .7.66 (102 mm HL, 335+ mm TL), collected with lectotype . Holotype of Coelorinchus sparsilepis: BSKU 28441 (73.3 mm HL, 227+ mm TL), northwest of Amami-oshima Island, Kagoshima Pref., Okinawa Trough, Japan, East China Sea , 29.7667ºN, 127.9833ºE, 713–770 m, F/ V Ryoanmaru, No. 28, tr. 73, bottom trawl, coll. Y. Kinoshita and S. Hagino, 20 Mar. 1978 . Non-types : Japan : BSKU 26327 (1, 52.8 mm HL, 277+ mm TL), off Senkaku Islands, Okinawa Trough , 25.6283ºN, 122.8933ºE, 560–692 m, F/ V Yuryo-maru, No. 8, tr. 3, bottom trawl, coll. T. Kitajima et al., 14 Jan. 1978 ; BSKU 57860 (1, 102 mm HL, 394+ mm TL), north of Miyako-jima Island, Okinawa Trough , 26.2500ºN, 125.2833ºE, 955–991 m, R/ V Tansei-maru, cr. KT-02-03, sta. E-2, trawl, coll. H. Endo, 26 Apr. 2002 ; BSKU 26557 (1, 61.8 mm HL, 221 mm TL) , BSKU 26559 (1, 70.6 mm HL, 251+ mm TL), off Miyakojima Island, Okinawa Trough , 26.4633ºN, 124.8483ºE, 680–770 m, F/ V Yuryo-maru, No. 8, tr. 10, bottom trawl, coll. S. Kishida and Y. Kinoshita, 23 Jan. 1978 ; BSKU 26427 (1, 52.3 mm HL, 185+ mm TL) , BSKU 26428 (1, 71.2 mm HL, 273 mm TL), north of Miyako-jima Island, Okinawa Trough , 26.3350ºN, 124.8450ºE, 1000–1140 m, F/ V Yuryo-maru, No. 8, tr. 7, bottom trawl, coll. S. Kishida and Y. Kinoshita, 22 Jan. 1978 ; BSKU 26498 (1, 137 mm HL, 502+ mm TL) , BSKU 26499 (1, 90.2 mm HL, 330+ mm TL) , BSKU 26500 (1, 103 mm HL, 357+ mm TL), northwest of Miyako-jima Island, Okinawa Trough , 25.2850ºN, 124.7800ºE, 910–990 m, F/ V Yuryo-maru, No. 8, tr. 8, bottom trawl, coll. S. Kishida and Y. Kinoshita, 22 Jan. 1978 ; BSKU 29896 (1, 96.9 mm HL, 321+ mm TL), west of Yaku-shima Island, Okinawa Trough , 30.7067ºN, 128.4683ºE, 790 m, F/ V Yuryo-maru, No. 8, sta. 6-T100, bottom trawl, coll. S. Tawara, 16 Jan. 1980 ; BSKU 26670 (1, 119 mm HL, 457+ mm TL), west of Yaku-shima Island, Okinawa Trough , 30.0300ºN, 128.3650ºE, 900 m, F/ V Yuryo-maru, No. 8, tr. 16-1, bottom trawl, coll. Y. Kinoshita and S. Hagino, 3 Feb. 1978 ; BSKU 29883 (1, 87.0 mm HL, 298+ mm TL), west of Yaku-shima Island, Okinawa Trough , 30.2067ºN, 128.2833ºE, 780–810 m, F/ V Yuryo-maru, No. 8, sta. 3-T1, bottom trawl, coll. H. Maeda, 26 Oct. 1979 ; BSKU 33463 (1, 103 mm HL, 377+ mm TL) , BSKU 33466 (1, 99.3 mm HL, 360+ mm TL) , BSKU 33467 (1, 92.3 mm HL, 311+ mm TL) , BSKU 33468 (1, 85.5 mm HL, 284+ mm TL) , BSKU 33470 (1, 93.1 mm HL, 345+ mm TL) , BSKU 33471 (1, 79.8 mm HL, 285+ mm TL) , BSKU 33472 (1, 79.8 mm HL, 275+ mm TL) , BSKU 33474 (1, 75.3 mm HL, 271+ mm TL) , BSKU 33476 (1, 89.7 mm HL, 288+ mm TL) , BSKU 33478 (1, 71.0 mm HL, 249+ mm TL) , BSKU 33480 (1, 59.3 mm HL, 210+ mm TL), west of Yaku-shima Island, Okinawa Trough , 30.2067ºN, 128.2833ºE, 780–810 m, F/ V Yuryo-maru, No. 8, sta. 3, tr. T1, bottom trawl, coll. H. Maeda, 26 Oct. 1979 ; BSKU 28548 (1, 115 mm HL, 385+ mm TL), northwest of Amami-oshima Island, Okinawa Trough , 29.8167ºN, 128.1000ºE, 915–932 m, F/ V Ryoan-maru, No. 28, tr. 75, bottom trawl, coll. Y. Kinoshita and S. Hagino, 20 Mar. 1978 ; BSKU 28507 (1, 75.6 mm HL, 247+ mm TL), northwest of Amamioshima Island, Okinawa Trough , 29.7333ºN, 128.0500ºE, 815 m, F/ V Ryoan-maru, No. 28, tr. 74, bottom trawl, coll. Y. Kinoshita and S. Hagino, 20 Mar. 1978 ; BSKU 28440 (1, 51.0 mm HL, 165+ mm TL), northwest of Amamioshima Island, Okinawa Trough , 29.7667ºN, 127.9833ºE, 713–770 m, F/ V Ryoan-maru, No. 28, tr. 73, bottom trawl, coll. Y. Kinoshita and S. Hagino, 20 Mar. 1978 ; BSKU 26989 (1, 113 mm HL, 432+ mm TL) , BSKU 26991 (1, 116 mm HL, 431+ mm TL) , BSKU 26993 (1, 90.3 mm HL, 296+ mm TL), northwest of Amami-oshima Island, Okinawa Trough , 29.6467ºN, 127.9733ºE, 830 m, F/ V Yuryo-maru, No. 8, tr. 19, bottom trawl, coll. Y. Kinoshita and S. Hagino, 4 Feb. 1978 ; BSKU 26949 (1, 98.9 mm HL, 334+ mm TL) , BSKU 26950 (1, 67.9 mm HL, 223+ mm TL), northwest of Amami-oshima Island, Okinawa Trough , 29.6483ºN, 127.9333ºE, 750–760 m, F/ V Yuryomaru, No. 8, tr. 18, bottom trawl, coll. Y. Kinoshita and S. Hagino, 4 Feb. 1978 ; BSKU 27115 (1, 81.6 mm HL, 283+ mm TL) , BSKU 27116 (1, 91.0 mm HL, 312+ mm TL) , BSKU 27117 (1, 69.7 mm HL, 251+ 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 ; SNFR 15177 (1, 60.2 mm HL, 205+ mm TL), East China Sea , 29.3050ºN, 127.4933ºE, 649–663 m, FRV Yoko-maru, sta. H-2, tr. 13, coll. T. Irie et al., 11 Sept. 1993 ; BSKU 28066 (1, 80.6 mm HL, 279+ mm TL) , BSKU 28067 (1, 87.1 mm HL, 272+ mm TL), northwest of Amami-oshima Island, Okinawa Trough , 28.8833ºN, 127.3000ºE, 820–830 m, F/ V Ryoan-maru, No. 28, tr. 60, bottom trawl, coll. Y. Kinoshita and S. Hagino, 16 Mar. 1978 ; BSKU 23132 (1, 69.9 mm HL, 250+ mm TL), Tosa Bay , 33.1500ºN, 133.6600ºE, 615 m, FRV Kaiyo-maru, cr. SK-75-2, sta. 10, tr. 1, 3-m beam trawl, 25 Jan. 1975 ; BSKU 69277 (1, 70.6 mm HL, 235+ mm TL), Tosa Bay , 33.1417ºN, 133.6433ºE, 582–597 m, FRV Kotaka-maru, otter trawl, 16 Jun. 1999 ; BSKU 46137 (1, 123 mm HL, 430+mm TL), Tosa Bay , 33.0400ºN, 133.6098ºE, 675–708 m, FRV Kotaka-maru, otter trawl, 22 May 1989 ; BSKU 44784 (1, 108 mm HL, 413+ mm TL), Tosa Bay , 700 m, FRV Kotaka-maru, otter trawl, 24 May 1988 ; MSM 13- 11 (1, 118 mm HL, 455+ mm TL), off Miho, Suruga Bay , 35.0032ºN, 138.5430ºE, 1282 m, 1.3-m larval net, 21 Feb. 2012 ; BSKU 14176 (1, 102 mm HL, 398+ mm TL), Sagami Bay, coll. O. Okamura, date unknown; NSMT-P 101339 (1, 117 mm HL, 393+ mm TL), off Yoron-jima Island, East China Sea , 27.1133ºN, 128.6983ºE, 870–945 m, R/ V Hakuho-maru, cr. KH-73-02, sta. 4, 3-m SA beam trawl, 24 Feb. 1973 . South China Sea: *ASIZP 66785 (1, 60.7 mm HL, 212+ mm TL), South China Sea , 20.8333ºN, 117.4500ºE, 731 m, otter trawl, coll. H.-M. Yeh et al., 17 Aug. 2005 .

Redescription based on Japanese specimens. General features are shown in Figs. 79–81 . Counts and measurements are given in Table 4 . Body deepest at first dorsal-fin origin, gradually tapering to long, laterally compressed tail. Trunk short, moderately compressed, width over pectoral-fin bases 1.0– 1.3 in depth below first dorsal-fin origin. Head large, HL about 3.1–3.9 in TL (5.1 in BSKU 26327, 52.8 mm HL). Snout long, acutely pointed, protruding well beyond upper jaw, length 1.4–2.0 times as long as orbit diameter; dorsal contour of snout almost straight to slightly concave in lateral view; lateral nasal ridge incompletely supported by nasal bone (often difficult to determine without radiographs or dissection, especially in large specimens); anterolateral margins of snout slightly convex when viewed dorsally. Orbit large, its greatest diameter 1.1–1.4 in postorbital length. Interorbital space broad, almost flat, width 1.0– 1.3 in orbit diameter. Mouth moderately small, inferior, protrusible, upper-jaw length 0.9–1.3 in orbit diameter; posterior margin of maxilla extending to vertical through hind 1/3 of orbit or beyond (but not reaching hind rim of orbit); lateral corner of mouth slightly restricted by skin folds; lips thin, slightly papillose near tooth bands. Suborbital region divided by stout, longitudinal bony ridge passing from tip of snout to posteroventral angle of opercle; its upper half almost vertical, lower half sharply inclined mesially. Preopercle large, posterior margin inclined, forming moderately angular lobe at posteroventral corner. Subopercle produced posteroventrally into narrowly pointed flap; posterior margin deeply concave. Gill membranes broadly connected across, and attached mesially to isthmus, with free posterior fold. Outer gill slit moderately restricted by skin folds, length 1.9–2.6 in orbit diameter. Gill rakers small, low, tubercular, armed with short, fine spines; no rakers on outer side of first arch and inner side of fourth arch; gill filaments moderately long. Chin barbel short, slender; length 2.3–4.4 in orbit diameter.

Anus abutting anal-fin origin. Periproct poorly developed. No external evidence of light organ anterior to anus. Pyloric caeca 12 (based on BMNH 1887.12.7.66, paralectotype).

Teeth small, conical, sharp, gently incurved, in narrow bands in both jaws. Premaxillary teeth in short, uniformly wide band, with about 5 tooth rows anteriorly; no teeth significantly enlarged; posterior margin of tooth band falling far short of lateral corner of mouth; teeth becoming progressively smaller inwardly. Mandibular teeth uniformly small, in narrow tapered band, with about 4 tooth rows across widest point near symphysis; posterior margin of tooth band reaching lateral corner of mouth. All teeth deeply embedded in thick layer of gum papillae.

Body scales large, thin, adherent, covered with stout, broadly trihedral, shield-like spinules in parallel to subparallel rows ( Fig. 31 C–F); in 122 mm HL specimen (BSKU 46137), those on dorsum below interdorsal space with 3–5 rows of spinules; middle row with about 5 spinules, notably higher and enlarged compared with adjacent rows, giving striated appearance to body surfaces; lateral rows often incomplete, not extending to posterior scale margin; spinules forming angle of about 45º to scale surface, greatly overlapping and closely adjoined to one another; height of spinules increasing posteriorly, with last spinule extending moderately beyond posterior scale margin (when rows complete); transverse buttresses well developed on each side of basal portion of each spinule; reticulate structures absent on unexposed potion. Body fully scaled except for fins.

Scales on head ridges prominently spiny and thickened; those on median rostral ridge usually covered with radiating rows of spinules. Terminal snout scute prominent, moderately long, diamond-shaped, dorsoventrally flattened, its length 2.1–3.7 in orbit diameter. Supraoccipital and posttemporal scutes stout, prominent, armed with single row of spinules. Scales on dorsal and lateral surfaces of head (including those between parietal ridges) covered with uniserial row of short, erect, keel-like spinules; spinules increasing in height posteriorly, broadly connected basally to one another, forming crest-like ridges; scales on opercle, preopercle, and postorbital and supratemporal canals largest. Scales on ventral surfaces of head similar to those on dorsum, but much smaller and not imbricate. Nasal fossa usually heavily scaled anteroventrally (scales rarely absent in some specimens). Dorsal surfaces of snout fully scaled, without naked clefts along each side of median rostral ridge. Underside of head completely and uniformly scaled except for narrow naked band above upper lip and anterior portion of mandibular rami. Posteroventral margins of preopercles only narrowly naked.

TABLE 4. (Continued)

No open pores along cephalic sensory canals. Free neuromasts prominent, serially arranged along head canals and lateral line, also sparsely distributed on dorsal surface of body; those on underside of head not especially enlarged; short hair-like papillae scattered over head surfaces (especially on underside of snout). Anterior nostril small and circular; posterior large, bean-shaped; septum between nostrils forming anteriorly opened hood. Lateral line complete, not interrupted throughout.

Origins of first dorsal and pelvic fins posterior to vertical through pectoral-fin base; first dorsal fin moderately high, its height 2.3–3.3 times as long as its base length (1.8 in BSKU 44784, 108 mm HL); second spinous ray not elongate, smooth along its leading edge (small denticle present distally in BSKU 33467, 89.7 mm HL); its tip usually extending beyond second dorsal-fin origin (not reaching this level in BSKU 44784).Interdorsal space narrow, 0.8–1.5 times as long as first dorsal-fin base length. Anal fin originating below or slightly posterior to second dorsal-fin origin (below bases of 1st–5th rays). Outer pelvic-fin ray prolonged, with fine distal tip.

Color when fresh ( Fig. 79 ). Head, body, and fins uniformly dark brown ( Fig. 79A ) to swarthy ( Fig. 79B ).

Color in alcohol ( Figs. 80–81 ). Head and body uniformly dark brown; orbit narrowly edged in black; lips dark; oral and gill cavities blackish; gill rakers and filaments light brown, arches darker; all fins blackish.

Size. Attains about 50 cm TL (BSKU 26498, 502 mm TL, Okinawa Trough , Japan).

Distribution. Known from off the Pacific coasts of southern Japan northward to the Miura Peninsula (139.62ºE), Okinawa Trough, and northern South China Sea, at depths of 360–1034 m ( Gilbert & Hubbs 1916; Shao et al. 2008a, 2008b; this study; Appendix 3-4F). Elsewhere reported from the western Coral Sea, and the Chesterfield and Bellona Plateaus, at depths of 412–1013 m ( Weber 1913; Weber & de Beaufort 1929; Iwamoto & Merrett 1997; Merrett & Iwamoto 2000; Last et al. 2014). Moderately common in the East China Sea, but rare in other parts of its range.

Comments on type specimens. Coelorinchus parallelus was originally described by G̹nther (1877) from “off Inoshima” (= Eno-shima Island, Kanagawa Pref.), Sagami Bay, Japan. Unfortunately, G̹nther’s (1877) original description is brief, without information on how many specimens he examined. However, in the “ Challenger ” Report, G̹nther (1887:125–127) provided a more detailed description of the species, noting that eight specimens were collected from “ Hyalonema -ground, off Inoshima” (Challenger sta. 232). Four of these were examined in the course of this study at the Natural History Museum, London (BMNH 1887.12.7.65–68, 221+–355+ mm TL; Fig. 80 ), two of which (BMNH 1887.12.7.67– 68, 221+–355+ mm TL) were re-identified as C. gilberti Jordan &Hubbs, 1925.According toWheeler& O’Riordan (1969), a 314 mm TL specimen is now deposited in the National History Museum of Ireland, Dublin (NMI block reg. no. 114.1899, fide Fricke et al. 2020). Another 280 mm TL specimen has also been transferred to the Muséum national d’Histoire naturelle, Paris (MNHN 1890-0125; Bailly et al. 1999; Fricke et al. 2020). The whereabouts of the remaining two specimens are unknown. To fix the name C. parallelus, BMNH 1887.12.7.65 (which represents what many authors have called C. parallelus ) is herein designated as a lectotype of this species ( Fig. 80 ), and the other specimens used in the original description automatically become paralectotypes.

G̹nther (1887) reported additional Challenger specimens of C. parallelus from off New Zealand (1 spec. from sta. 169), off the Kermadec Islands (3 and 2 spec. from sta. 170A and 171 respectively), and the south of Japan (1 spec. from sta. 235), but these specimens are not included in the type series of this species. Five of them are present in the BMNH collection; none represents the true C. parallelus , but rather C. gilberti (BMNH 1887.12.7.69, 1 spec., 136+ mm TL, from sta. 235; G̹nther 1887: pl. XXIX, fig. A′), C. kermadecus Jordan & Gilbert in Jordan & Starks, 1904 (BMNH 1887.12.7.60–62, 3 spec., 176+–549+ mm TL, from sta. 170A; G̹nther 1887: pl. XXIX, fig. A), and C. trachycarus Iwamoto, McMillan & Shcherbachev, 1999 (BMNH 1887.12.7.59, 1 spec., 448+ mm TL, from sta. 169).

Nomenclaturaldiscussion. Okamura&Yatou(1984) described C. sparsilepis based on a single specimen ( Fig. 81 ) collected from the Okinawa Trough, Japan. Despite its close similarity to C. parallelus and their sympatric distribution in the area, Okamura & Yatou (1984) did not compare the two species. Yatou (1984:224–225, 370) also reported C. parallelus in the same book without comments on C. sparsilepis . The close similarity between C. sparsilepis and C. parallelus was first recognized by Iwamoto & Merrett (1997:502), who suggested that the two species are not separable except for the suborbital width (38% of orbit diameter in C. sparsilepis vs. 50– 62.5% in C. parallelus ) and orbit diameter (2.1 in snout length vs. 1.7–1.8).

A re-examination of the holotype of C. sparsilepis confirmed that the suborbital width is 52% of the orbit diameter, and the orbit is 1.90 in the snout length. Furthermore, these data fall within the ranges of variation for the additional specimens of C. parallelus examined (suborbital width 46–59% of orbit diameter; orbit diameter 1.44–1.95 snout length). Additionally, no significant differences were found in other characters, including counts and measurements ( Table 4 ), dentition, and squamation. Consequently, C. sparsilepis is herein regarded as a junior synonym of C. parallelus .

Remarks. Yanai (1950) listed C. parallelus from the Sea of Japan off San’in, noting that the species was commonly found in Matsue and Hamada in Shimane Pref. On the basis of Yanai’s list, many subsequent authors (e.g., Lindberg & Legeza 1969; Shinohara et al. 2014) believed the species occurred in the Sea of Japan. However, considering its deeper vertical distribution (usually> 600 m depth), Yanai’s C. parallelus appears to represent misidentified C. multispinulosus Katayama, 1942 , the only species of grenadiers commonly found in the southern part of the Sea of Japan. In fact, no voucher specimens of C. parallelus collected from the area were found in museum collections.

Ueno (1965, 1971) reported C. parallelus from off the Pacific coast of Hokkaido, but it is most likely to represent misidentified C. gilberti , a species occasionally found in the Pacific off northern Japan. Maeda & Maruyama (1991), Maeda & Tsutsui (2003), and Nakabo & Kai (2013:1874) also doubted Ueno’s records of C. parallelus .

According to Okamura (1970a:198), other records of C. parallelus by Japanese ichthyologists before the 1970s should be considered suspect, and probably represent misidentifications of C. kamoharai Matsubara, 1943 or C. multispinulosus .

G̹nther (1887) reported C. parallelus from Kermadec Island and New Zealand, but Jordan & Gilbert (in Jordan & Starks 1904:618–619) considered G̹nther’s (1887) additional specimens specifically distinct from the Japanese population, providing a new scientific name, C. kermadecus , for the former. Subsequently, in their synonymy of C. parallelus, Gilbert & Hubbs (1920:515) suggested that the New Zealand specimen represents another undescribed species. The species is now known as C. trachycarus widely distributed in Australasian waters.

Weber (1913) reported C. parallelus from Indonesia, including the Savu, Flores, Ceram, and Halmahera Seas. However, Gilbert & Hubbs (1920:151) suggested that Weber’s (1913) specimens have a much shorter snout than the Japanese material they examined. Weber (1913: pl. IV, fig. 3) also illustrated his C. parallelus as lacking scales on the nasal fossa. However, the fossa of Japanese specimens is heavily scaled ventrally, which further implies that Weber’s specimens represent a different species.

A Hawaiian record of C. parallelus by Gilbert & Cramer (1897) was re-identified as C. aratrum Gilbert, 1905 in the original description of the latter species.

Smith’s (1953) C. parallelus from the western Indian Ocean is attributed to a misidentification of C. braueri Barnard, 1925 . His illustration (fig. 232) clearly shows important diagnostic features of that species, including an elongate spinous ray of the first dorsal fin, a long, attenuated snout, and the dorsal contour of the snout greatly convex in lateral view.

Kyushin et al. (1973) recorded C. parallelus from the Andaman Sea, but his specimen (HUMZ 90186) is reidentified here as Coelorinchus sp. cf. kermadecus in this study.

The following records of C. parallelus from the Atlantic and Indian Oceans seem to represent other species of the subgenus Oxygadus Gilbert & Hubbs, 1920 (see also Iwamoto 1990:179): Alcock (1889, 1899) from the Gulf of Manner; Brauer (1906) from the South Atlantic; Zugmayer (1911) from the Mid-Atlantic Ridge in the North Atlantic; and Fowler (1936) from the eastern Atlantic.

Relationships and comparisons. Coelorinchus parallelus is a distinctive species of the C. parallelus group (see the Relationships of C. divergens ), and differs most notably from other members of that group in that the occipital scales are covered with a single crest-like row of spinules (vs. multiple divergent rows of spinules). In addition, it differs notably from C. acanthiger Barnard, 1925 in having fewer scales below the first dorsal-fin origin (4.5–7 vs. 7–10) and lacking a prominent naked area atop the head between the parietal ridges; from C. amirantensis Iwamoto, Golani, Baranes & Goren, 2006 and C. yurii Iwamoto, Golani, Baranes & Goren, 2006 in that the underside of the head is densely scaled (vs. sparsely scaled); from C. braueri and C. yurii in having a lower first dorsal fin (height 48–77% PRL vs.>98%); from C. mycterismus McMillan & Paulin, 1993 in that the dorsal contour of the snout is almost straight to slightly concave in lateral view (vs. distinctly concave); and from C. trachycarus in that the ventral surfaces of the preopercles are completely scaled (vs. broadly naked). Coelorinchus parallelus also differs from all except C. divergens Okamura & Yatou, 1984 , C. kermadecus , C. mycterismu s, and C. spinifer Gilbert & Hubbs, 1920 in that the nasal fossa is usually heavily scaled (vs. completely or generally naked); and from C. amirantensis and C. spinifer in having a shorter snout (67–89% PRL vs.>93%).

Figures

FIGURE 31. Scanning electron micrographs showing body scales (from the dorsum below the interdorsal space) of two species of the Coelorinchus occa group.(A–B) C. divergens, BSKU33464, paratype, 81.6 mm HL; (C–D) C. parallelus, BMNH 1887.12.7.65, lectotype, 93.2 mm HL; (E–F) C. parallelus, BSKU 28441, holotype of C. sparsilepis, 73.3 mm HL. (A, C, E) Views from above; (B, D, F) oblique views. [Photos: (A–B, E–F) NSMT; (C–D) N. Nakayama]

FIGURE 79. Fresh specimens of Coelorinchus parallelus. (A) BSKU 46137, 123 mm HL, 430+ mm TL, Tosa Bay, Kochi Pref., Pacific, 675–708 m depth; (B) BSKU 44784, 108 mm HL, 413+ mm TL, Tosa Bay, Pacific, 700 m depth. Lateral views. [Photos: BSKU]

FIGURE 80. Lectotype of Macrurus parallelus (= Coelorinchus parallelus). BMNH 1887.12.7.65, 93.2 mm HL, 325+ 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 81. Preserved specimen of Coelorinchus parallelus. BSKU 28441, holotype of C. sparsilepis, 73.3 mm TL, 227+ mm TL, Okinawa Trough, East China Sea, 770–713 m depth. (A) Lateral view; (B) dorsal and (C) ventral views of the head and trunk. [Photos: N. Nakayama]