Hymenocephalus longibarbis Günther, 1887

Nakayama, Naohide, 2020, Grenadiers (Teleostei: Gadiformes: Macrouridae) of Japan and adjacent waters, a taxonomic monograph, Megataxa 3 (1), pp. 1-383 : 213-215

Hymenocephalus longibarbis Günther, 1887

[Japanese name: Wanidara]

( Figs. 139–140 ; Appendix 3-8C)

Hymenocephalus longibarbis G̹nther, 1887:139, pl. XVIII, fig. C [original description; holotype: BMNH 1887.12 .7.94, from Fiji Islands, Challenger sta. 173, 19º09′35ʺS, 179º41′50ʺE, in 315 ftm (576 m)]; Schwarzhans 2014:27, fig. 8 (description; comparison; H. longiceps a junior synonym) .

Hymenocephalus longiceps Smith & Radcliffe in Radcliffe, 1912:111 pl. 23, fig. 3 [original description; holotype: USNM 72927, from off southeastern Luzon Island, Albatross sta. 5459, 13º10ʹ21ʺN, 123º59ʹ54ʺE, in 201 ftm (368 m)]; Kamohara 1937:188 (first record from Japan; brief description; spec. from Kochi; new Japanese name: “Wanidara”); Okada & Matsubara 1938:451 (in key; Japan); Kamohara 1938:70 (brief description; spec. from Kochi Pref.); Kamohara 1950:278 (listed; Kochi and Wakayama Pref.); Chen 1951:210 (listed; Taiwan); Kamohara 1952:97 (brief description; spec. from Kochi Pref.); Matsubara 1955:1314 (in key; Japan); Kamohara 1958:73 (listed; Kochi Pref.); Kamohara 1964:96 (listed; Kochi Pref.); Matsubara 1965:507 (compiled; Japan); Okamura 1970a:45, pl. XIV (description; 9 spec. from Pacific off southern Japan off Owase and Kochi); Okamura 1970b: table 1 (listed; Japan); Tominaga & Uyeno 1981:489 (listed; Japan); Yatou 1982:140 [brief description; in part, 4 spec. from Tosa Bay; 1 spec. from Kyushu-Palau Ridge is H. hachijoensis (ZMUT KP416)]; Ozawa 1983:13 (listed; off Makurazaki, Kagoshima Pref., East China Sea); Okamura 1984a:199, 357, fig. 140 [brief description; 5 spec. from Okinawa Trough; photo based on BSKU spec. (catalog no. unknown)]; Okamura 1984b:92, pl. 80, fig. D (compiled); Okamura 1988:92, pl. 80, fig. D (compiled); Nakabo 1993:355 (in key; Japan); Shao 1993:171 (compiled; Taiwan); Okamura 1997:128, fig. 1 (compiled); Nakabo 2000:419 (in key; Japan); Shinohara et al. 2001:305 (listed; Tosa Bay); Nakabo 2002:419 (in key; Japan); Yoda et al. 2002:11 (listed; East China and Yellow Seas); Chiou et al. 2004a: table 1 (listed; Taiwan); Shinohara et al. 2005:417 (listed; Ryukyu Islands); Shao et al. 2008b: table 2 (41 spec. listed from northeastern and southwestern Taiwan, and South China Sea); Furuhashi et al. 2010: table 2 (2 spec. listed from northern Okinawa Trough); Nakabo & Kai 2013:495 (in key; Japan); Iwamoto et al. 2015:75 (brief description; 47 spec. from northeastern and southwestern Taiwan, South China Sea, and Philippines); Iwatsuki et al. 2017:32 (listed; Hyuga-nada); Motomura 2020:39 (listed; Japan).

Diagnosis. A species of Hymenocephalus with 8 pelvicfin rays; barbel very long, length 53–72% PRL, its tip extending to vertical through hind margin of orbit or beyond when depressed; snout low, depressed, length 26– 33% PRL; tip of snout scarcely, if at all, protruding beyond upper jaw; orbit diameter 35–42% PRL; interorbital width 18–27% PRL; first dorsal-fin rays II,9–10; pectoral-fin rays i12–i16; gill rakers on first arch (outer/inner) 13– 18/19–23, on second arch 18–22/18–21; pyloric caeca 18–25; body uniformly dark gray dorsally; lower half of tail generally immaculate; caudal vertebrae not visible externally; ostial and caudal colliculi of otolith not fused.

Material examined. 30 specimens. Japan : BSKU 106798 (1, 40.9 mm HL, 219+ mm TL) , BSKU 106799 (1, 27.6 mm HL, 156+ mm TL) , BSKU 106800 (1, 37.0 mm HL, 202+ mm TL), southeast of Shimokoshiki-jima Island, East China Sea , 31.5560ºN, 129.8847ºE, 415 m, F/ V Maruko-maru, tr. 4, bottom trawl, coll. N. Nakayama et al., 24 Apr. 2012 ; KAUM-I. 32209 (1, 37.4 mm HL, 225 mm TL), off Nomaike , Kagoshima, 31.5000ºN, 129.8833ºE, 370–400 m, trawl, coll. M. Yamashita and Y. Ohashi, 10 Sept. 2010 ; FFNU P-00623 (2, 28.6–33.3 mm HL), east of Okihirazi Bank, East China Sea , 32.2635ºN, 129.5428ºE, 263 m, T/ V Nagasaki-maru, cr. N207, sta. 1, 3-m ORE beam trawl, coll. J. Hashimoto, 11 Nov. 2005 ; FFNU P-00707 (2, 32.8–44.8 mm HL), east of Okihirazi Bank, East China Sea , 32.2260ºN, 129.5293ºE, 402 m, T/ V Nagasaki-maru, cr. N254, sta. B4-1, 3-m ORE beam trawl, coll. J. Hashimoto, 12 Mar. 2008 ; FFNU P-00777 (1, 35.4 mm HL), east of Hirazi Bank, East China Sea , 32.2485ºN, 129.4720ºE, 403 m, T/ V Nagasaki-maru, cr. N276, sta. B4, 3-m ORE beam trawl, coll. J. Hashimoto, 7 Mar. 2009 ; BSKU 113721 (1, 28.0 mm HL, 165+ mm TL) , BSKU 113723 (1, 35.8 mm HL, 208+ mm TL) , BSKU 113725 (1, 23.6 mm HL, 141+ mm TL), off Aki, Tosa Bay , 320–400 m, F/ V Kosei-maru, bottom trawl, coll. N. Nakayama et al., 8 Apr. 2014 ; BSKU 92382 (1, 44.7 mm HL, 239+ mm TL), Mimase fish market, F/ V Kosei-maru, bottom trawl, coll. N. Nakayama, 20 Nov. 2007 ; BSKU 112440 (1, 43.0 mm HL, 235+ mm TL) , BSKU 112441 (1, 51.1 mm HL, 267+ mm TL), BSKU 112443 (1, 40.4 mm HL, 223 mm TL), BSKU 112446 (1, 45.6 mm HL, 233+ mm TL), BSKU 112448 (1, 44.7 mm HL, 236+ mm TL), BSKU 112449 (1, 50.6 mm HL, 264+ mm TL), BSKU 112901 (1, 42.3 mm HL, 239+ mm TL), BSKU 112914 (1, 42.2 mm HL, 213+ mm TL), BSKU 112917 (1, 32.9 mm HL, 190+ mm TL), BSKU 113071 (1, 33.5 mm HL, 206 mm TL), BSKU 113072 (1, 42.6 mm HL, 233+ mm TL), BSKU 113075 (1, 31.5 mm HL, 190+ mm TL), off Susaki, Tosa Bay, 320–380 m, F/V Kosei-maru, bottom trawl, coll. N. Nakayama et al., 9 Mar. 2014; BSKU 113077 (1, 49.5 mm HL, 265+ mm TL), BSKU 113078 (1, 46.8 mm HL, 237+ mm TL), BSKU 113082 (1, 35.1 mm HL, 199+ mm TL), BSKU 113083 (1, 39.7 mm HL, 225+ mm TL), BSKU 113652 (1, 36.8 mm HL, 213 mm TL), off Okitsu, Tosa Bay, 380 m, F/V Kosei-maru, bottom trawl, coll. N. Nakayama et al., 11 Mar. 2014.

Counts and measurements. Based on 30 specimens (23.6–51.1 mm HL, 141+–267+ mm TL). Counts: first dorsal-fin rays II,9–10; pectoral-fin rays i12–i16; pelvicfin rays 8; gill rakers on first arch (outer/inner) 13–18/19– 23, on second arch 18–22/18–21; longitudinal scales 15–18; transverse scale rows below first dorsal-fin origin 2.5–4, below first dorsal-fin midbase 2–3, below second dorsal-fin origin 2–3.5, above anal-fin origin 6–10; pyloric caeca 18–25; rete-gas gland complexes 2.

The following measurements are in% of HL, followed by those in % of PRL in parentheses: snout length 21–25 (26–33); orbit diameter 28–33 (35–42); postorbital length 46–52 (59–65); postrostral length 77–81; orbit–preopercle distance 41–45 (52–57); suborbital width 8–11 (10–14); upper-jaw length 52–58 (66–73); length of rictus 45–50 (57–64); length of premaxillary tooth band 42–48 (53– 61); preoral length 5–12 (7–15); distance between tip and lateral angle of snout 12–19 (15–24); snout width 19–25 (25–32); internasal width 14–19 (18–24); interorbital width 14–21 (18–27); occipital width 8–11 (10–14); body width over pectoral-fin bases 45–67 (57–84); body depth at first dorsal-fin origin 65–86 (81–107); body depth at anal-fin origin 51–61 (65–78); prepelvic length 100–117 (126–151); preanus length 176 (225); preanal length 164–184 (209–233); isthmus–pelvic distance 54–68 (68–87); isthmus–anus distance 120 (154); isthmus–anal distance 122–145 (154–184); pelvic–anal distance 68–90 (87–115); pelvic-fin length 85–122 (109–153); pectoralfin length 47–56 (58–72); predorsal length 98–109 (122– 139); height of first dorsal fin 59–85 (74–107); length of first dorsal-fin base 34–47 (44–58); interdorsal length 74– 100 (93–127); length of gill slit 30–35 (38–44); length of posterior nostril 1–7 (2–9); barbel length 42–56 (53–72).

Size. To about 27 cm TL (BSKU 112441, 267+ mm TL, Mimase, Japan).

Distribution. Widely distributed from Japan to Australia, including the Philippines, Indonesia, Fiji, and the New Caledonian region, at depths of 200–820 m (G̹nther 1887; Radcliffe 1912; Gilbert & Hubbs 1920; Weber & de Beaufort 1929; Iwamoto & Merrett 1997; Iwamoto & Williams 1999; Merrett & Iwamoto 2000; Iwamoto & Graham 2001; Shao et al. 2008a, 2008b; Last et al. 2014; Schwarzhans 2014; Iwamoto et al. 2015; this study). In Japan, known from off the Pacific coasts northward to the Izu Peninsula (138.96ºE) and the Okinawa Trough at depths of 200‾ 555 m (Appendix 3-8C). Usually rare, but numerous specimens were occasionally collected in Tosa Bay.

Remarks. Hymenocephalus longibarbis has been well described by previous authors, and thus does not need repeating here. For a full description see Gilbert & Hubbs (1920; as H. longiceps ), Okamura (1970a; as H. longiceps ), and Iwamoto & Merrett (1997); otolith morphology was detailed by Schwarzhans (2014).

Hymenocephalus longibarbis was described by G̹nther (1887) based on a single specimen collected during the “ Challenger ” Expedition from the Fiji Islands. Subsequently, Smith & Radcliffe (in Radcliffe 1912) described H. longiceps from the Albay Gulf, the southeast of Luzon, the Philippines. Although these species have been considered valid by most previous authors (e.g., Okamura 1970a; Iwamoto 1990; Iwamoto & Merrett 1997; Iwamoto & Williams 1999), Schwarzhans (2014) showed that H. longiceps is a junior synonym of H. longibarbis ; this study follows his treatment.

Relationships and comparisons. Hymenocephalus longibarbis is one of two species of the H. longibarbis group as defined by Schwarzhans (2014). The only other member of this group is H. longipes Smith & Radcliffe in Radcliffe, 1912 restricted to marginal seas of the Philippines. Hymenocephalus longibarbis differs most notably from H. longipes in the presence of a welldeveloped barbel at the symphysis of the lower jaw (53–72% PRL vs. absent). The two species are further distinguished from each other by the color of the pelvic fin (uniformly dusky in H. longibarbis vs. intensely black distally in H. longipes ).

Figures

FIGURE 139. Fresh specimens of Hymenocephalus longibarbis. (A) BSKU 92382, 44.7 mm HL, 239+ mm TL, Mimase fish market, Kochi Pref., Pacific; (B–C) BSKU 112441, 51.1 mm HL, 267+ mm TL, Tosa Bay off Susaki, Kochi Pref., Pacific. (A) Lateral view; (B) dorsal and (C) ventral views of the head and trunk. [Photos: N. Nakayama]

FIGURE 140. Scanning electron micrographs showing a body scale (from the chest) of Hymenocephalus longibarbis. BSKU 113072, 42.6 mm HL. (A) View from above; (B) oblique view. [Photos: NSMT]