Coryphaenoides Gunnerus, 1765

Nakayama, Naohide, 2020, Grenadiers (Teleostei: Gadiformes: Macrouridae) of Japan and adjacent waters, a taxonomic monograph, Megataxa 3 (1), pp. 1-383 : 139-141

Genus Coryphaenoides Gunnerus, 1765

[Japanese name: Hokakedara-zoku]

Coryphaenoides Gunnerus, 1765:50 (type species: Coryphaenoides rupestris Gunnerus, 1765 , by monotypy).

Lepturus Gronow in Gray, 1854:165 [type species: Lepturus brevirostris Gronow in Gray, 1854, by monotypy; objectively invalid, preoccupied by Lepturus Moehring, 1758 (see also Moehring 1752) and Lepturus Brisson, 1760 in Aves (see also Grant & Mackworth-Praed 1956)].

Chalinura Goode & Bean, 1883:198 [type species: Chalinura simula Goode & Bean, 1883 , by original designation; objectively invalid, preoccupied by Chalinura Dalman, 1826 in Arachnida (see also Dunlop & Jekel 2008), replaced by Fuyangia Whitley, 1931 ].

Lionurus G̹nther, 1887:141 [as subgenus of Macrurus ; type species: Coryphaenoides filicauda G̹nther, 1878, by subsequent designation by Jordan & Evermann (1898)].

Nematonurus G̹nther, 1887:150 [as subgenus of Macrurus ; type species: Macrurus armatus Hector, 1875 , by subsequent designation by Jordan & Evermann (1898)].

Moseleya Goode & Bean, 1896:417 (type species: Coryphaenoides longifilis G̹nther, 1877, by original designation; objectively invalid, preoccupied by Moseleya Quelch, 1884 in Coelenterata, replaced by Dolloa Jordan, 1900 ).

Albatrossia Jordan & Everman, 1898 :2573 (type species: Macrourus pectoralis Gilbert, 1891 , by original designation).

Bogoslovius Jordan & Evermann, 1898:2574 (type species: Bogoslovius clarki Jordan & Gilbert in Jordan & Evermann, 1898, by original designation).

Dolloa Jordan, 1900:897 (type species: Coryphaenoides longifilis G̹nther, 1877, by original designation; replacement name for Moseleya Goode & Bean, 1896 ).

Ateleobranchium Gilbert & Burke, 1912:94 (type species: Ateleobrachium pterotum Gilbert & Burke, 1912 , by original designation).

Fuyangia Whitley, 1931:334 (type species: Chalinura simula Goode & Bean, 1883 , by original designation; replacement name for Chalinura Goode & Bean, 1883 ).

Hemimacrurus Fraser-Brunner, 1935:322 (type species: Macrurus acrolepis Bean, 1884 , by original designation).

Cariburus Parr, 1946:57 (type species: Macrurus zaniophorus Vaillant, 1888 , by original designation).

Diagnosis. Anus immediately anterior to anal-fin origin; periproct absent or rudimentary. Ventral light organ absent. Infraorbital ridge not connected with preopercular ridge, separated by distinct gap. Second spinous ray of first dorsal fin serrated along its leading edge (serrations rarely rudimentary or lost). Tip and lateral angles of snout armed with stout tubercles in most species. Chin barbel present. Pelvic fin inserted below or posterior to (rarely slightly anterior to) pectoral-fin base. Anal-fin origin well posterior to hind margin of first dorsal-fin base. Body scales lacking reticulate structure; buttresses of spinules generally absent. Scales along second dorsal and anal fins not enlarged. Grooved lateral line complete (rarely interrupted anteriorly). Cephalic sensory pores present or absent. Rete-gas gland complexes 4–7. Branchiostegal rays 6. Color variable, without prominent silvery reflection when fresh. [Modified from Iwamoto & Sazonov (1988).]

Remarks. Coryphaenoides is the second largest genus of the family, with about 65 species currently recognized (Iwamoto et al. 2015; Nakayama & Endo 2016a; Fricke et al. 2020), 15 of which are herein recorded from the study area. Species of the genus are widely known from the deep demersal habitat of the world’s oceans, with a few occurring at hadal depths [i.e., C. armatus ( Hector, 1875) , C. leptolepis G̹nther, 1877, and C. yaquinae Iwamoto & Stein, 1974 ; see the Remarks and Range extension of each species]. Coryphaenoides is seemingly abundant in mid- and high-latitude regions, but appears to be rare in tropical waters. The genus also includes some commercially exploited species ( Iwamoto 1990; Iwamoto et al. 2015), viz., C. rupestris Gunnerus, 1765 (northeastern Atlantic), C. acrolepis ( Bean, 1884) (North Pacific), and C. pectoralis ( Gilbert, 1891) (North Pacific).

Key to species of Coryphaenoides from Japan and adjacent waters

1a Mandibular teeth arranged in 1 or 2 rows (especially evident laterally and posteriorly) ...................................................... 2

1b Mandibular teeth arranged in distinct band.......................... 6

2a Interdorsal space shorter than (0.3–0.8 times as long as) first dorsal-fin base length; barbel rudimentary or short, length 1–8% HL .............................................................................. 3

2b Interdorsal space longer than (1.2–3.0 times as long as) first dorsal-fin base length; barbel well developed, length 13–25% HL ........................................................................................ 4

3a Pelvic-fin rays 5–8; first dorsal-fin rays II,8–10; mandibular teeth arranged in uniserial row; snout conical in lateral view, moderately protruding beyond upper jaw; outer pelvic-fin ray not especially prolonged .................................... C. pectorali s

3b Pelvic-fin rays 9–10; first dorsal-fin rays II,12–15; mandibular teeth arranged in 2 rows, with inner row distinctly enlarged; snout bluntly rounded in lateral view, barely protruding beyond upper jaw; outer pelvic-fin ray greatly prolonged..... ............................................................................. C. longifilis

4a Premaxillary teeth in wide tapered band, with outer row of enlarged canines and inner band of villiform teeth; body generally pale overall ......................................... C. leptolepis

4b Premaxillary teeth arranged in 1–2 rows or narrow band; body uniformly dark brown .......................................................... 5

5a Inner premaxillary teeth, if present, arranged in uniserial row; mandibular teeth arranged in 1 distinct row near symphysis; scaly patches present on lower half of the suborbital region and posterior portion of mandibular rami ............ C. armatus

5b Inner premaxillary teeth arranged in 2–3 irregular rows or narrow band; mandibular teeth arranged in 2 irregular rows near symphysis; lower half of suborbital region and mandibular rami completely naked..................... C. yaquinae

6a Mouth small, posterior margin of maxilla not reaching vertical through midorbit (upper-jaw length 28–32% HL), lateral corner of mouth moderately restricted by lip folds.............. 7

6b Mouth large, posterior margin of maxilla extending to vertical through midorbit or beyond (upper-jaw length 33–44% HL); lateral corner of mouth not restricted by lip folds................ 9

7a Spinules on body scales arranged in tightly packed convergent rows; leading edges of snout narrowly naked; interpelvic width distinctly greater than (or rarely about equal to) pelvic-fin base length ....................................................... C. nasutus

7b Spinules on body scales arranged in tightly packed parallel to subparallel rows; leading edges of snout fully scaled; interpelvic width less than pelvic-fin base length................ 8

8a Last spinules on body scales scarcely overlapping posterior scale margin; underside of snout with broad naked band above upper lip; preopercle naked along ventral margin.................. ......................................................................... C. marginatus

8b Last spinules on body scales greatly overlapping posterior scale margin; underside of snout only narrowly naked above upper lip; preopercle almost completely scaled..................... ............................................................................... C. microps

9a Outer gill slit greatly restricted by skin folds, length less than half orbit diameter (5–10% HL) ........................................ 10

9b Outer gill slit moderately wide, length greater than half orbit diameter (15–26% HL) ...................................................... 12

10a Underside of snout fully scaled; spinules on body scales arranged in tightly packed convergent rows or quincunx order; pelvic-fin rays 9–10........................................ C. rudis

10b Underside of snout with prominent naked area; spinules on body scales arranged in slightly divergent rows; pelvic-fin rays 11–12 ........................................................................... 11

11a Middle row of body-scale spinules distinctly higher than adjacent rows; dorsal contour of head smoothly curved from snout tip to first dorsal-fin origin; orbit diameter 23% HL; pectoral-fin rays i24 .................................................. C. asper

11b Middle row of body-scale spinules not especially higher than adjacent rows; dorsal contour of head prominently humped over nape, with distinct depression above orbits; orbit diameter 20–21% HL; pectoral-fin rays i19–i22 ................... ................................................................................. C. soyoae

12a Scales on head and body adherent, those along leading edge of snout and infraorbital ridge slightly thickened and enlarged; barbel well developed, length 11–19% HL; pelvic-fin rays usually 8 (rarely 7 or 9); body uniformly black in adults ...... ............................................................................. C. acrolepis

12b Scales on head and body deciduous, those along leading edge of snout and infraorbital ridge not modified; barbel rudimentary to short, length 3–11% HL; pelvic-fin rays usually 9 (rarely 8 or 10); body pale to dusky ................... 13

13a No prominent modified scales on snout; pectoral fin not reaching vertical through anal-fin origin ........... C. altipinnis

13b Snout tipped with prominent enlarged tubercles; pectoral fin extending to or beyond vertical through anal-fin origin ........ ............................................................................................ 14

14a Snout relatively broad, its width, 24–30% HL, internasal width 21–27% HL; spinules on body scales arranged in parallel to subparallel rows ................................................... C. cinereus

14b Snout relatively narrow, its width, 19–22% HL, internasal width 16–18% HL; spinules on body scales arranged in narrowly divergent rows .......................................... C. filifer