Cetonurus globiceps (Vaillant, 1884)

Nakayama, Naohide, 2020, Grenadiers (Teleostei: Gadiformes: Macrouridae) of Japan and adjacent waters, a taxonomic monograph, Megataxa 3 (1), pp. 1-383 : 23-25

Cetonurus globiceps (Vaillant in Filhol, 1884) [Japanese name: Dango-hige]

( Figs. 16–17 ; Appendix 3-1B)

Macrurus globiceps Vaillant in Filhol, 1884:183 (original description; lectotype: MNHN 1886-92, from Spanish Sahara, 23º57ʹN, 17º12ʹW, in 1400–1435 m; 8 paralectotypes); Eschmeyer 1998:653 (lectotype designation).

Cetonurus globiceps: Goode & Bean 1896:411 (new combination); Marshall 1973:613, fig. 35 ( C. robstus a junior synonym); Shao et al. 2008b: table 2 (3 spec. listed from southeastern Taiwan and South China Sea; first record from Taiwan); Iwamoto et al. 2015:45, fig. 4 (brief description; 5 spec. from Taiwan and Philippines).

Cetonurus robustus Gilbert & Hubbs, 1916:207 , pl. 11, fig. 2 [original description; holotype: USNM 76870, from “off the east coast of central Hondo” (off Cape Shionomisaki), Albatross sta. 4971, in 649 ftm (1187 m); 5 paratypes from Albatross sta. 4791 and 4973]; Okada & Matsubara 1938:453 (in key; Japan); Matsubara 1955:1317 (in key; Japan: new Japanese name: “Dango-hige”); Matsubara 1965:510 (compiled; Japan); Okamura 1970a:110, pl. XXIV, textfig. 46 (description based on 1 spec. from Molucca Sea); Okamura 1970b: table 1 (listed; Japan); Tominaga & Uyeno 1981:488 (listed; Japan); Okamura 1984b:94, pl. 345, fig. E (compiled); Okamura 1988:94, pl. 345, fig. E (compiled); Nakabo 1993:357 (in key; Japan); Nakabo 2000:421 (in key; Japan); Nakabo 2002:420 (in key; Japan); Nakabo & Kai 2013:497 (in key; Japan); Motomura 2020:38 (listed; Japan).

Diagnosis. Differs from its only congener, C. crassiceps , in having the following combination of features: orbit diameter 21–34% HL; premaxillary teeth in 3–4 rows, with outer series slightly enlarged; mandibular teeth in 2–4 rows throughout; tail fully scaled along anal-fin base; transverse scale rows below first dorsal-fin origin 13–19 (usually 16– 18), below second dorsal-fin origin 10–19 (usually 14–15). [From Sazonov & Shcherbachev (1985).]

Material examined. 7 specimens. Holotype of Cetonurus robstus: USNM 76870 (57.5 mm HL, 280+ mm TL), off Cape Shionomisaki, Wakayama Pref., Kii Peninsula, Japan , 33.3917ºN, 135.5667ºE, 649 ftm (1187 m), Albatross sta. 4971, 9-ft. Agassiz beam trawl, 30 Aug. 1906 . Paratypes of C. robstus: USNM 76874 (1, ca. 29 mm HL, 113+ mm TL), off Cape Shionomisaki , 33.4042ºN, 135.5083ºE, 600 ftm (1098 m), Albatross sta. 4973, 9-ft Agassiz beam trawl, 30 Aug. 1906 ; CAS-SU 22923 (2, 48.0– 60.3 mm HL, 241+–250+ mm TL), USNM 76871 (2, 46.9–59.6 mm HL, 261+–280+ mm TL), off Cape Shionomisaki , 33.3917ºN, 135.5667ºE, 649 ftm (1187 m), Albatross sta. 4971, 9-ft Agassiz beam trawl, 30 Aug. 1906 . Non-type: Japan: HUMZ 146791 (1, 42.2 mm HL, 142+ mm TL), west of Amami-oshima Island, Okinawa Trough , 28.5548ºN, 127.1660ºE, 996– 999 m, 16 Jul. 1994 .

Counts and measurements. Based on 7 specimens (ca. 29–60.3 mm HL, 113+–280+ mm TL). Counts: first dorsal-fin rays II,9–11; pectoral-fin rays i14–i19; pelvic-fin rays 9–10; gill rakers on first arch (outer/inner) 5–12/13–14, on second arch 12–14/11–14; longitudinal scales 59–70; transverse scale rows below first dorsalfin origin 14–17, below first dorsal-fin midbase 16–18, below second dorsal-fin origin 12–13.

The following measurements are in % of HL, followed by those in % of PRL in parentheses: snout length 33–38 (47–55); orbit diameter 23–27 (32–39); postorbital length 45–51 (65–70); postrostral length 69–73; orbit–preopercle distance 47–52 (68–72); suborbital width 22–30 (32–41); upper-jaw length 29–33 (41–45); length of rictus 23–25 (33–36); length of premaxillary tooth band 11–14 (16–19); preoral length 24–34 (33–47); distance between tip and lateral angle of snout 22–28 (32–41); snout width 38–44 (54–65); internasal width 33–43 (47–63); interorbital width 40–41 (56–59); body width over pectoral-fin bases 34–43 (49–59); body depth at first dorsal-fin origin 69–80 (94– 114); body depth at anal-fin origin 64–68 (92–97); prepelvic length 98–111 (142–159); preanus length 114–126 (166– 181); preanal length 120–130 (175–186); isthmus–pelvic distance 28–33 (41–45); isthmus–anus distance 49 (71); isthmus–anal distance 55 (78–81); pelvic–anal distance 28–31 (40–45); anus–anal distance 7 (10–11); pectoralfin length 36 (52); predorsal length 100–104 (140–151); height of first dorsal fin 54 (77); length of first dorsal-fin base 17–20 (24–27); interdorsal length 28–38 (41–53); length of gill slit 9–12 (13–17); length of posterior nostril 4–6 (6–8); barbel length 3–5 (4–7).

Size. Attains at least 51 cm TL ( Sazonov & Shcherbachev 1985).

Distribution. Widespread in tropical and temperate waters of the world’s oceans at depths of 860–4621 m ( Sazonov & Shcherbachev 1985; Iwamoto & Graham 2001). In Japanese waters, known only from off the Kii Peninsula and northern Okinawa Trough at depths of 996‾ 1187 m (Appendix 3-1B). Very rare in Japan, but seemingly less rare in other parts of its range.

Remarks. Cetonurus globiceps is quite rare in Japanese waters, and its occurrence was previously based on only the type specimens of C. robstus Gilbert & Hubbs, 1916 , a junior synonym of the former species. The latter species was originally described from six specimens collected from off Cape Shionomisaki, Wakayama Pref. An additional specimen from the Okinawa Trough (HUMZ 146791, heavily damaged) represents the first record of C. globiceps from the East China Sea and the second confirmed record of the species from Japanese waters. For further morphological information see Gilbert & Hubbs (1916; original description of C. robstus ).

Figures

FIGURE 16. Preserved specimen of Cetonurus globiceps. USNM 76870, holotype of C. robstus, 57.5 mm HL, 280+ mm TL, off Cape Shionomisaki, Wakayama Pref., Pacific, 1187 m depth. (A) Lateral view; (B) dorsal and (C) ventral views of the head and trunk. [Photos: N. Nakayama]

FIGURE 17. Scanning electron micrographs showing a body scale (from the dorsum below the interdorsal space) of Cetonurus globiceps. USNM 76871, paratype of C. robstus, 56.6 mm HL. (A) View from above; (B) oblique view. [Photos: N. Nakayama]