Coryphaenoides marginatus Steindachner & Döderlein, 1887

Nakayama, Naohide, 2020, Grenadiers (Teleostei: Gadiformes: Macrouridae) of Japan and adjacent waters, a taxonomic monograph, Megataxa 3 (1), pp. 1-383 : 184-190

Coryphaenoides marginatus Steindachner & Döderlein, 1887

[Japanese name: Heri-dara]

( Figs. 119–121 , 122 A–B; Table 9 ; Appendix 3-6F)

Coryphaenoides marginatus Steindachner & D̂derlein, 1887:284 [original description; 1 spec. from “Tokio”, but probably from Eno-shima Island, Sagami Bay; see Amaoka (2007:28)]; Jordan & Snyder 1901:120 (listed; Japan); Jordan & Gilbert in Jordan & Starks 1904:610 [after Steindachner & D̂derlein (1887)]; Jordan et al. 1913:415 (listed; Japan; new Japanese name: “Heri-dara”); Gilbert & Hubbs 1916:164 (description; 43 spec. from East China Sea and Suruga Bay); Okada & Matsubara 1938:449 (in key; Japan); Kuroda 1951:391 (listed; Suruga Bay); Kuroda 1952:176 (2 spec. from Suruga Bay); Matsubara 1955:1309 (in key; Japan); Matsubara 1965:504 (compiled; Japan); Okamura 1970a:136, pl. XXX, text-figs. 54–55 (description; biological notes; 43 spec. from Pacific off southern Japan from Choshi to Suruga Bay); Tominaga & Uyeno 1981:489 (listed; Japan); Okamura 1982:165, 352, fig. 100 [brief description; 1 spec. from Tosa Bay (BSKU 29492)]; Ohta 1983: photo. 27, tables A–B (listed; Suruga Bay; in situ observation); Yatou 1984:219, 363, fig. 154 [brief description; 10 spec. from Okinawa Trough; photo based on BSKU 29492 (from Tosa Bay)]; Okamura 1984b:95, pl. 82, fig. E (compiled); Okamura 1988:95, pl. 82, fig. E (compiled); Iwamoto 1990:214, fig. 492 (synopsis); Nakabo 1993:365 (in key; Japan); Suzuki & Kataoka 1997:82, pl. 33, fig. 177 (brief description; 1 spec. from Kumano-nada); Okamura 1997:126, fig. 2 (compiled); Shinohara & Matsuura 1997:291 (listed; Suruga Bay); Nakabo 2000:429 (in key; Japan); Shinohara et al. 2001:305 (12 spec. listed from Tosa Bay); Nakabo 2002:429 (in key; Japan); Yoda et al. 2002:11 (listed; East China and Yellow Seas); Shinohara et al. 2005:417 (2 spec. listed from Ryukyu Islands); Fukui et al. 2008:286, figs. 3–4 (descriptions of early life stages; Suruga Bay); Kitagawa et al. 2008:41, unnumbered fig. (brief description; spec. from Pacific off Tohoku); Shinohara et al. 2009:708 (listed; Pacific off Tohoku); Kim et al. 2009b:107, fig. 2 (brief description; 10 spec. from Korea, Taiwan, and Japan; new Korean record); Furuhashi et al. 2010: table 2 (160 spec. listed from northern Okinawa Trough); Nakabo & Kai 2013:505 (in key; Japan); Miyazaki et al. 2019: fig. 3B, table1 (4 spec. listed from Tokyo Submarine Canyon); Motomura 2020:39 (listed; Japan).

Coryphaenoides awae Jordan & Gilbert in Jordan & Starks, 1904:608, unnumbered fig. (original description; holotype: CAS-SU 8547, from “off Nanaura in Awa at the entrance of by of Tokyo”); Jordan et al. 1913:416, fig. 387 (listed; Japan; new Japanese name: “Bōshū-soko-dara”); Gilbert & Hubbs 1916:166 (additional measurements of holotype); Okada & Matsubara 1938:449 (in key; Japan); Kuroda 1951:391 (listed; Suruga Bay); Kuroda 1952:176 (1 spec. from Suruga Bay); Matsubara 1955:1309 (in key; Japan).

Coryphaenoides (Coryphaenoides) marginatus: Okamura 1970b : table 1 (listed; Japan).

Diagnosis. Pelvic-fin rays 6–9 (usually 8). Snout short, slightly protruding beyond upper jaw. Tip and lateral angles of snout armed with stout tubercles; scales along head ridges not coarsely modified. Mouth small, posterior margin of upper jaw not extending beyond vertical through midorbit; upper-jaw length 28–32% HL; lateral corner of mouth moderately restricted by skin folds. Outermost gill slit greatly restricted by skin folds, length 3–9% HL. Barbel moderately short, stout at base, length 5–14% HL. Teeth all small, conical, in wide bands in both jaws, none especially enlarged. Body scales covered with short, greatly reclined, needle-like spinules in tightly packed parallel rows; tip of last spinule in each row scarcely extending beyond posterior scale margin. Transverse scale rows below first dorsal-fin midbase 5.5–8.5. Top of snout fully scaled; underside of head with broad naked band above upper lip. Second spinous ray of first dorsal fin moderately to greatly prolonged, height of first dorsal fin equal to or greater than HL (101–219% HL); serration along its leading edge rudimentary in adults; first dorsalfin rays II,9–11. Pelvic-fin bases closer together, their interspace less than base length of each fin. Body generally dusky brown overall.

Material examined. 45 specimens. Holotype of Coryphaenoides awae: CAS-SU 8547 (sex undetermined, 117 mm HL, 622+ mm TL), west of southern Chiba Pref. (Awa), Japan, date unknown. Non-types : Japan: BSKU 27128 (1 sex undetermined, 33.2 mm HL, 186+ mm TL), northwest of Amami-oshima Island , Okinawa Trough , 29.3833ºN, 127.5150ºE, 650 m, F/ V Yuryomaru, No. 8, tr. 21, bottom trawl, coll. Y. Kinoshita and S. Hagino, 5 Feb. 1978 ; BSKU 27925 (1 female, 42.6 mm HL, 237+ mm TL), northwest of Amami-oshima Island , Okinawa Trough, 28.7500ºN, 127.1167ºE, 520–542 m, F/ V Ryoan-maru, No. 28, tr. 58, bottom trawl, coll. Y. Kinoshita and S. Hagino, 16 Mar. 1978 ; BSKU 71614 (1 male, 38.4 mm HL, 230+ mm TL), BSKU 71615 (1 sex undetermined, 26.9 mm HL, 152+ mm TL), Tosa Bay , 33.1950ºN, 133.6750ºE, 528–537 m, FRV Kotaka-maru, cr. 97-5-500, otter trawl, 13 May 1997 ; BSKU 69280 (1 sex undetermined, 49.6 mm HL, 254+ mm TL), Tosa Bay , 33.1417ºN, 133.6433ºE, 528–537 m, FRV Kotaka-maru, cr. 97-5-500, otter trawl, 13 May 1997 ; BSKU 23284 (1 male, 73.4 mm HL, 445 mm TL), Mimase fish market, bottom trawl, date unknown ; BSKU 29492 (1 female, 61.7 mm HL, 348+ mm TL), Tosa Bay , 32.9667ºN, 133.5333ºE, 605 m, F/ Vs Shinsei-maru, No. 53 and Kyoyo-maru, No. 2, tr. T-19, bottom trawl, coll. O. Okamura et al., 21 Dec. 1979 ; BSKU 103049 (1 male, 66.7 mm HL, 378 mm TL), BSKU 103052 (1 female, 105 mm HL, 541 mm TL), BSKU 103055 (1 female, 102 mm HL, 512+ mm TL), Suruga Bay , 350 m, coll. A. Fukui and M. Takami, 13 Oct. 2009 ; BSKU 103067 (1 female, 81.0 mm HL, 444+ mm TL), BSKU 103070 (1 female, 75.1 mm HL, 409+ mm TL), Suruga Bay , 500 m, coll. A. Fukui and M. Takami, 2 Oct. 2009 ; BSKU 103060 (1 male, 60.6 mm HL, 360+ mm TL), BSKU 103061 (1 sex undetermined, 54.5 mm HL, 323+ mm TL), BSKU 103062 (1 male, 60.5 mm HL, 349+ mm TL), BSKU 103063 (1 sex undetermined, 61.9 mm HL, 355+ mm TL), BSKU 103064 (1 male, 64.5 mm HL, 381+ mm TL), BSKU 103066 (1 male, 73.4 mm HL, 450 mm TL), Suruga Bay , 500 m, coll. A. Fukui and M. Takami, 3 Aug. 2009 ; BSKU 103057 (1 female, 80.1 mm HL, 396+ mm TL), BSKU 103059 (1 male, 85.5 mm HL, 452+ mm TL), Suruga Bay , coll. A. Fukui and M. Takami, 11 Jun. 2009 ; BSKU 103033 (1 female, 92.9 mm HL, 449+ mm TL), Suruga Bay , coll. A. Fukui and M. Takami, 12 Dec. 2007 ; BSKU 103047 (1 male, 71.6 mm HL, 420+ mm TL), BSKU 103048 (1 female, 71.4 mm HL, 392 mm TL), Suruga Bay , coll. A. Fukui and M. Takami, 13 Jun. 2007 ; BSKU 103044 (1 female, 89.1 mm HL, 463 mm TL), BSKU 103045 (1 male, 44.0 mm HL, 252+ mm TL), BSKU 103046 (1 male, 68.1 mm HL, 413 mm TL), Suruga Bay , coll. A. Fukui and M. Takami, 16 2009 ; BSKU 103034 (1 male, 71.6 mm HL, 404+ mm TL), BSKU 103035 (1 female, 96.5 mm HL, 536 mm TL), BSKU 103036 (1 female, 81.1 mm HL, 450 mm TL), BSKU 103037 (1 sex undetermined, 73.7 mm HL, 421+ mm TL), BSKU 103038 (1 male, 52.8 mm HL, 324+ mm TL), BSKU 103039 (1 male, 60.4 mm HL, 362 mm TL), BSKU 103040 (1 male, 79.4 mm HL, 461+ mm TL), Suruga Bay , coll. A. Fukui and M. Takami, 23 Jul. 2009 ; BSKU 110135 (1 sex undetermined, 72.0 mm HL, 405 mm TL), Suruga Bay , 34.7619ºN, 138.4811ºE, 196–387 m, F/ V Hinode-maru, sta. 5, bottom trawl, coll. N. Nakayama and R. Misawa, 23 Apr. 2013 ; BSKU 110113 (1 male, 69.4 mm HL, 404+ mm TL), BSKU 110114 (1 male, 74.0 mm HL, 439 mm TL), BSKU 110115 (1 female, 57.4 mm HL, 336 mm TL), BSKU 110116 (1 male, 59.3 mm HL, 369 mm TL), BSKU 110117 (1 male, 77.0 mm HL, 457 mm TL), BSKU 110118 (1 male, 70.3 mm HL, 422+ mm TL), Suruga Bay , 34.7489ºN, 138.4664ºE, 200–450 m, F/ V Hinode-maru, sta. 6, bottom trawl, coll. N. Nakayama and R. Misawa, 23 Apr. 2013 ; BSKU 110121 (1 female, 96.4 mm HL, 525 mm TL), BSKU 110122 (1 male, 59.7 mm HL, 378+ mm TL), BSKU 110123 (1 male, 63.5 mm HL, 381+ mm TL), Suruga Bay , 34.7127ºN, 138.4553ºE, 262–434 m, F/ V Hinode-maru, sta. 1, bottom trawl, coll. N. Nakayama and R. Misawa, 23 Apr. 2013 ; FRLM 1780 (1 sex undetermined, 74.6 mm HL), 20 km southwest of Inohana , Kumano-nada, 900–1100 m, fish trap, 29 Nov. 1978.

Counts and measurements. See Table 9 .

Size. Attains about 62 cm TL ( CAS-SU 8547 , holotype of Coryphaenoides awae , 622+ mm TL, west of southern Chiba Pref., Japan).

Variation. Serrations along the second spinous ray of the first dorsal fin are better developed in smaller specimens than in larger ones. Those of adults are somewhat rudimentary, giving a moderately smooth appearance to the leading edge.

Sexual dimorphism and dichromatism. Females attain a much larger body size than males, with the largest female measuring 541 mm in TL (vs. 461+ mm in males). Compared with females, males have a narrower cheek (orbit–preopercle distance 37–41% HL vs. 40–44%), a wider interorbital (20–24% HL vs. 16–20%), and a larger posterior nostril (7–11% HL vs. 6–8%). Sexual dichromatism is also evident, with females having a much paler body than males ( Fig. 119 A–C vs. D–G). In females, the first dorsal and pelvic fins are mostly pale except for dark apical bands, whereas in males, those fins are uniformly blackish.

Development. Early life stage was fully described by Fukui et al. (2008), with a complete ontogenetic series of eggs and larvae.

Distribution. Known only from Japan and Korea at depths of 115‾ 1165 m ( Kim et al. 2009b; this study; Appendix 3-6F). Shao et al. (2008a, 2008b) reported this species from Taiwan, but their specimens are currently referred to as C. microps (Smith & Radcliffe in Radcliffe, 1912) (see Iwamoto et al. 2015). Abundant in southern Japan, but rare in the east of the Boso Peninsula (139.89ºE).

Remarks. Coryphaenoides marginatus was originally described from a single specimen collected from Tokyo, Japan (probably originally from off Enoshima Island, Sagami Bay; Amaoka 2007:28). Although the holotype is thought to be in the Naturhistorisches Museum, Vienna (NMW; Fricke et al. 2020), it is now missing among that collection (K. Amaoka pers. com.). For a full description see Okamura (1970a).

Iwamoto in Randall & Lim (2000) listed C. marginatus from the South China Sea, but its occurrence needs to be verified by voucher specimens. Although Shao et al. (2008a, 2008b) recorded C. marginatus from Taiwan, their specimens were re-identified as C. microps by Iwamoto et al. (2015). Coryphaenoides marginatus appears to be restricted to Japan and Korea.

Nomenclatural discussion. Jordan & Gilbert (in Jordan & Starks 1904) described Coryphaenoides awae as a new species based on a single specimen collected from off Nanaura, Awa, southern part of Chiba Pref., Japan ( Fig. 120 ), suggesting its close relationship with C. marginatus .According to the original description, C. awae differs from C. marginatus in having a larger and broader head (HL 5.3 in TL vs. ca. 5.75; head width 1.83 in HL vs. 2.25), a deeper body (depth 5.3 in TL vs. ca. 7.5), a smaller orbit (4.33 in HL vs. 3.6), a shorter snout (3.4 in HL vs. 3.83), and more spinule rows on the body scales (13–17 vs. 12). Jordan & Gilbert (in Jordan & Starks 1904) further distinguished the two species by head squamation: in C. awae , the underside of the head is naked along margins of the interopercle and mandibular rami, and above the side of the upper lip, whereas the naked areas of C. marginatus are confined to inner margins of the mandibular rami. As far as I know, no additional specimens of C. awae have been recorded since the original description.

Okamura (1970a) was the first who recognized the two nominal species to be synonymous, although he did not examine the holotype of C. awae . All subsequent authors have followed his conclusion, and C. awae is currently regarded as a junior synonym of C. marginatus (e.g., Kuroda 1971; Iwamoto 1990; Kim et al. 2009b). To reconfirm this synonymy, the holotype of C. awae was examined in this study (sex was not determined to avoid further damage to the specimen), and it was compared with additional materials of C. marginatus .

The holotype of C. awae (117 mm HL, 622 mm TL) is distinctly larger than the C. marginatus specimens examined (26.9–105 mm HL, 152+– 541 mm TL), and this made a comparison of morphometric characters dubious. However, despite their size differences, data of C. awae generally lie within range of variation of C. marginatus ( Table 9 ). The holotype of C. awae differs from the specimens of C. marginatus examined in having a shorter preoral (11% HL vs. 14–19%), a narrower internasal (14% vs. 15–20%), and a deeper body (depth below first dorsal-fin origin 97% HL vs. 69–91%). However, the above differences are attributable to size-related variation, considering allometric growth of these characters in C. marginatus ( Fig. 121 ). Also, no significant differences were found in meristic characters between the two species, except for outer gill rakers on the first arch (2 in C. awae vs. 3–5 in C. marginatus ). However, the subtle difference in gill rakers seems to reflect ontogenetic variation, and the count range for C. marginatus may extend to two when larger specimens become available for study. In large individuals of C. marginatus (especially females), the underside of the head is broadly naked above the upper lip and along the margins of the interopercle, preopercle, and mandibular rami. This condition agrees well with the description of C. awae given by Jordan & Gilbert (in Jordan & Starks 1904), and thus the two species cannot be distinguished by head squamation. Due to the lack of adequate comparative materials, the possibility of there being two species cannot be fully discussed in this study. However, there is little reason to doubt their conspecificity, and C. awae is therefore regarded here as a junior synonym of C. marginatus .

Relationships. Coryphaenoides marginatus belongs to the subgenus Coryphaenoides (sensu Iwamoto 1990) . It falls into a group of species that Gilbert & Hubbs (1920:413) defined by the combination of “a produced dorsal spine, a deep and sharply compressed body, and a dorsal contour horizontal behind the first dorsal fin”. According to Shcherbachev & Iwamoto (1995:300), this group is further characterized by having “a relatively small, restricted mouth opening; low, slightly protruding snout; small teeth in bands lacking a prominently enlarged series; small barbel; and highly restricted gill openings”. Other members of the group are: C. macrolophus ( Alcock, 1889) , C. microps , C. semiscaber Gilbert & Hubbs, 1920 , and C. tydemani ( Weber, 1913) . Shcherbachev & Iwamoto (1995) provided comparisons of these species except C. marginatus . This group is called here the C. marginatus group.

Comparisons. Coryphaenoides marginatus is readily distinguished from other members of the C. marginatus group by spinulation on the body scales. In C. marginatus , spinules on the body scales are distinctly short, with the last spinule in each spinule row barely overlapping the posterior scale margin ( Fig. 122 A–B); the spinules of the other four species are much longer, and the tips of the last spinules extend well beyond that level ( Shcherbachev & Iwamoto 1995; this study; see also Fig. 122 C–D). It further differs from all in having a broad naked band above the upper lip (vs. ventral surfaces of snout and suborbital shelf completely scaled or only narrowly naked; Shcherbachev & Iwamoto 1995; this study). Coryphaenoides marginatus also differs from C. macrolophus in that the preopercle is broadly rounded posteroventrally (vs. sharply angulated at posteroventral corner; Shcherbachev & Iwamoto 1995:303); from C. microps in having a larger orbit (22–31% HL vs. 19–22%) and a shorter postorbital (42–51% HL vs. 50– 55%), and in that the mandibular rami are only narrowly scaled medially (vs. almost completely scaled, except for anterior portions) and the preopercle is naked along its ventral margin (vs. almost completely scaled); from C. semiscaber in having a shorter pelvic fin (50–85% HL vs. 95–96%; Shcherbachev & Iwamoto 1995:299, fig. 4); and from C. tydemani in having a longer isthmus–pelvic distance (39–48% HL vs. 31–37%) and a lower first dorsal fin (101–219% HL vs. 238–276%).

In Japanese waters, C. marginatus is collected with C. nasutus G̹nther, 1877, with which it might be confused in the field. However, the two species are readily distinguished from each other by the positions of the pelvic fins. In C. marginatus , the pelvic fins are inserted closer together and the interpelvic distance is less than the base length of each fin ( Figs. 119C, F , 120C ), whereas in C. nasutus , the fins are well separated by a broad gap that is greater than their base length ( Figs. 125C , 126C ). The two species are further distinguished by squamation characters. Coryphaenoides marginatus differs from C. nasutus in that spinules on the body scales are arranged in tightly packed parallel rows ( Fig. 122A vs. convergent rows, Fig. 122E ). The top of the snout is fully scaled in C. marginatus , whereas that of C. nasutus is narrowly naked along the leading edges. Serrations of the first dorsal fin are fewer and less developed in C. marginatus than in C. nasutus (number of serrations 0–13 vs. 20–35). Females of C. marginatus differ notably from C. nasutus in that the distal margins of the first dorsal and pelvic fins are prominently outlined in black (vs. fins uniformly dark in C. nasutus ). The two species are difficult to distinguish by morphometric characters, although C. marginatus tends to have a shorter interdorsal space (10–58% HL vs. 34–114%) and a higher first dorsal fin (101–219% HL vs. 78–125%). Regarding meristic characters, C. marginatus differs from C. nasutus in modal counts of pelvic-fin rays [8 (range 6–9), vs. 9 (8–10)] and gill rakers on the outer side of the second arch [10 (9–12) vs. 9 (8–10)].

Figures

FIGURE 119. Fresh specimens of Coryphaenoides marginatus. (A–C) BSKU 103046, male, 68.1 mm HL, 413 mm TL; (D–F) BSKU 103048, female, 71.4 mm HL, 392 mm TL; (G) BSKU 103052, female, 105 mm HL, 541 mm TL. All specimens from Suruga Bay, Shizuoka Pref., Pacific. (A, D, G) Lateral views; (B, E) dorsal and (C, F) ventral views of the head and trunk. [Photos: N. Nakayama]

FIGURE 120. Preserved specimen of Coryphaenoides marginatus. CAS-SU 8547, holotype of C. awae, 117 mm HL, 622+ mm TL, west of southern Chiba Pref., Pacific. (A) Lateral view; (B) dorsal and (C) ventral views of the head and trunk. [Photos: N. Nakayama]

FIGURE121. Scatter diagrams showing relationships of the (A) preoral length, (B) internasal width, and (C) body depth at the first dorsal-fin origin (as % HL) to HL (mm) in Coryphaenoides marginatus. Orange squares indicate the holotype of C. awae.

FIGURE 122. Scanning electron micrographs showing body scales (from the dorsum below the interdorsal space) of three species of the Coryphaenoides marginatus group. (A–B) C. marginatus, BSKU 103048, 71.4 mm HL; (C–D) C. microps, ASIZP 66413, 43.7 mm HL; (E–F) C. nasutus, BSKU 103042, 78.5 mm HL. (A, C, E) Views from above; (B, D, F) oblique views. [Photos: NSMT]

FIGURE 125. Fresh specimen of Coryphaenoides nasutus. BSKU 103042, 78.5 mm HL, 383+ mm TL, Suruga Bay, Shizuoka Pref., Pacific. (A) Lateral view; (B) dorsal and (C) ventral view of head and trunk. [Photos: N. Nakayama]

FIGURE 126. Lectotype of Coryphaenoides nasutus, BMNH 1887.12.7.78, 81.2 mm HL, 337+ mm TL, off Cape Omaezaki, Enshu-nada, Pacific, 1034 m depth. (A) Lateral view; (B) dorsal and (C) ventral view of head and trunk. Preserved condition. [Photos: N. Nakayama]