Ventrifossa longibarbata Okamura, 1982

Nakayama, Naohide, 2020, Grenadiers (Teleostei: Gadiformes: Macrouridae) of Japan and adjacent waters, a taxonomic monograph, Megataxa 3 (1), pp. 1-383 : 294-298

Ventrifossa longibarbata Okamura, 1982

[Japanese name: Okina-hige]

( Figs. 202–204 , 205 A–B; Appendix 3-12E)

Ventrifossa longibarbata Okamura, 1982:157 , fig. 94 (original description; holotype:BSKU 29494,from Tosa Bay, 32º58.0ʹN, 133º32.0ʹE, in 605 m; 4 paratypes from Suruga Bay, Tosa Bay, and Okinawa Trough, in 382–620 m; new Japanese name: “Okina-hige”); Okamura 1984a:215, 361, fig. 150 (brief description; 43 spec. from Okinawa Trough; photo based on BSKU 29891); Okamura 1984b:93, pl. 81, fig. C (compiled); Okamura 1988:93, pl. 81, fig. C (compiled); Nakabo 1993:358 (in key; Japan); Okamura 1997:128, fig. 10 [compiled; photo spec. is V. rhipidodorsalis (BSKU unknown)]; Shinohara & Matsuura 1997:292 (listed; Suruga Bay); Nakabo 2000:422 (in key; Japan); Shinohara et al. 2001:306 (26 spec. listed from Tosa Bay); Nakabo 2002:422 (in key; Japan); Yoda et al. 2002:11 (listed; East China and Yellow Seas); Chiou et al. 2004a:48, fig. 20, table 1 (brief description; 4 spec. from Dong-gang; first record from Taiwan); Shinohara et al. 2005:418 (listed; Ryukyu Islands); Suetsugu & Ohta 2005: table 3 (listed; Enshu-nada); Shao et al. 2008b: table 2 (37 spec. listed from northeastern, southeastern, and southwestern Taiwan, and South China Sea); Furuhashi et al. 2010: table 2 (21 spec. listed from northern Okinawa Trough); Nakabo & Kai 2013:498 (in key; Japan); Iwamoto et al. 2015:110 (brief description; 45 spec. from northeastern and southwestern Taiwan, and South China Sea); Motomura 2020:39 (listed; Japan).

Diagnosis. Second spinous ray of first dorsal fin finely serrated along its leading edge; prominent black spot on center of first dorsal fin (often indistinct in juveniles and preserved specimens); anal fin uniformly dusky; prominent black spot absent on front of premaxillary ascending process; oral cavity pale; median rostral ridge lacking narrow blackish streak; leading edges of snout, supranarial ridges, and suborbital shelves only faintly marked with black; dorsal parts of trunk and tail dark, sharply demarcated from paler lateral and ventral parts of body (especially prominent in fresh specimens); snout low, slightly protruding beyond upper jaw, preoral length 16–20% HL; no scute-like scale at snout tip; body scales covered with short, moderately erect, needle-like spinules in quincunx order; spinules on scales along second dorsalfin base not enlarged; body scales small, transverse scale rows below midbase of first dorsal fin 8.5–11.5, below second dorsal-fin origin 7–9.5; longitudinal scales 46–56; area of spinuleless scales posterior to first dorsal-fin base only narrowly developed; outer series of premaxillary teeth slightly enlarged; mandibular teeth arranged in narrow tapered band; suborbital shelf not greatly constricted anteriorly; inner gill rakers on first arch 14– 16, outer gill rakers on second arch 13–17; orbit large, greatest diameter 34–39% HL; upper-jaw length 43–48% HL; interorbital space moderately narrow, width 21–26% HL; chin barbel long, length 31–38% HL; pectoral-fin length 55–68% HL.

Material examined. 28 specimens. Holotype of Ventrifossa longibarbata: BSKU 29494 (49.7 mm HL, 279+ mm TL), Tosa Bay, Japan , 32.9667ºN, 133.5333ºE, 605 m, F/ Vs Shinsei-maru, No. 53 and Kyoyo-maru, No. 2, cr. 4- Ky, tr. 19, bottom trawl, coll. O. Okamura et al., 21 Dec. 1979 . Paratypes of V. longibarbata: BSKU 34003 (1, 51.7 mm HL, 282+ mm TL), west of Yakushima Island, Okinawa Trough , 30.2083ºN, 128.2088ºE, 600–620 m, F/ V Yuryo-maru, No. 8, sta. 3-T2, bottom trawl, coll. H. Maeda, 26 Oct. 1979 ; BSKU 30495 (1, 28.5 mm HL, 161+ mm TL) , BSKU 30496 (1, 41.3 mm HL, 210+ mm TL), collected with holotype. Non-types: Japan : FFNU P-00770 (1, 40.3 mm HL, 244+ mm TL), east of Okihirazi Bank, East China Sea , 32.1635ºN, 129.4663ºE, 494 m, T/ V Nagasaki-maru, cr. N275, sta. B5, 3-m ORE beam trawl, coll. J. Hashimoto, 3 Dec. 2008 ; BSKU 109021 (1, 26.9 mm HL, 141+ mm TL), west of Okikasayama Bank , 32.1503ºN, 129.0072ºE, 499–504 m, T/ V Nagasaki-maru, cr. N365, sta. C5, 3- m ORE beam trawl, coll. N. Nakayama, 19 Nov. 2012 ; BSKU 28601 (1, 38.9 mm HL, 215+ mm TL), northwest of Amami-oshima Island, Okinawa Trough , 29.9500ºN, 128.0000ºE, 585–610 m, F/ V Ryoan-maru, No. 28, tr. 76, bottom trawl, coll. Y. Kinoshita and S. Hagino, 20 Mar. 1978 ; BSKU 28371 (1, 41.9 mm HL, 211+ mm TL), northwest of Amami-oshima Island, Okinawa Trough , 29.7333ºN, 127.8000ºE, 495–510 m, F/ V Ryoan-maru, No. 28, tr. 72, bottom trawl, coll. Y. Kinoshita and S. Hagino, 19 Mar. 1978 ; BSKU 27185 (1, 37.2 mm HL, 182+ mm TL) , BSKU 27192 (1, 47.3 mm HL, 244+ mm TL) , BSKU 27194 (1, 44.3 mm HL, 237+ mm TL), northwest of Amami-oshima Island, Okinawa Trough , 29.4333ºN, 127.5167ºE, 570 m, F/ V Yuryo-maru, No. 8, tr. 22, bottom trawl, coll. Y. Kinoshita and S. Hagino, 5 Feb. 1978 ; BSKU 27124 (1, 55.4 mm HL, 294+ 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 ; BSKU 28003 (1, 54.7 mm HL, 283+ mm TL), northwest of Amami-oshima Island, Okinawa Trough , 28.8333ºN, 127.2333ºE, 700–740 m, F/ V Ryoan-maru, No. 28, tr. 59, bottom trawl, coll. Y. Kinoshita and S. Hagino, 16 Mar. 1978 ; BSKU 27580 (1, 58.2 mm HL, 306+ mm TL), northwest of Amami-oshima Island, Okinawa Trough , 28.7167ºN, 127.2333ºE, 750–755 m, F/ V Ryoan-maru, No. 28, tr. 48, bottom trawl, coll. Y. Kinoshita and S. Hagino, 11 Mar. 1978 ; BSKU 77922 (1, 35.1 mm HL, 188+ mm TL), south of Muroto , 33.0790ºN, 134.1645ºE, 414–513 m, R/ V Tansei-maru, cr. KT-05-29, sta. K-500, beam trawl, coll. H. Endo et al., 17 Nov. 2005 ; BSKU 78008 (1, 35.6 mm HL, 190+ mm TL), Tosa Bay , 33.2083ºN, 133.6983ºE, 526–539 m, FRV Kotaka-maru, otter trawl, 3 Mar. 1999 ; BSKU 44417 (1, 51.9 mm HL, 249+ mm TL), Tosa Bay , 600 m, FRV Kotaka-maru, otter trawl, 11 Jan. 1988 ; BSKU 101609 (1, 48.0 mm HL, 226+ mm TL) , BSKU 101618 (1, 51.5 mm HL, 289+ mm TL) , BSKU 101619 (1, 47.5 mm HL, 272+ mm TL) , BSKU 101620 (1, 34.3 mm HL, 191+ mm TL) , BSKU 101623 (1, 35.7 mm HL, 191+ mm TL), Tosa Bay , 33.1428ºN, 133.6248ºE, 450–480 m, FRV Kotaka-maru, otter trawl, 1 Aug. 1988 ; BSKU 12919 (1, 43.1 mm HL, 247+ mm TL) , BSKU 12920 (1, 42.6 mm HL, 222+ mm TL), Tosa Bay , 350–450 m, bottom trawl, 14 May 1968 ; BSKU 99326 (1, 42.8 mm HL, 265 mm TL) , BSKU 99327 (1, 49.5 mm HL, 288+ mm TL) , BSKU 99328 (1, 34.7 mm HL, 205+ mm TL), off Kochi, 600 m, bottom trawl, 24 Mar. 1989 ; * NSMT-P 92270 (1, 14.4 mm HL, 84+ mm TL), off Miyagi, FRV Wakataka-maru , sta. E-350, coll. T.P. Satoh, 25 Oct. 2008 .

Counts and measurements. Based on 27 specimens (26.9–58.2 mm HL, 141+–306+ mm TL). Counts: first dorsal-fin rays II,9–11; pectoral-fin rays i21–i26; pelvic-fin rays 8–9; gill rakers on first arch (outer/inner) 9– 14/14–16, on second arch 13–17/13–16; longitudinal scales 46–56; transverse scale rows below first dorsal-fin origin 10.5–14.5, below first dorsal-fin midbase 8.5–11.5, below second dorsal-fin origin 7–9.5.

The following measurements are in % of HL, followed by those in % of PRL in parentheses: snout length 26–30 (34–39); orbit diameter 34–39 (45–53); postorbital length 39–44 (51–58); postrostral length 74– 78; orbit–preopercle distance 37–43 (49–57); suborbital width 12–14 (15–19); upper-jaw length 43–48 (56–64); length of rictus 37–41 (48–56); length of premaxillary tooth band 31–35 (41–47); preoral length 16–20 (20–27); distance between tip and lateral angle of snout 15–18 (20–23); snout width 27–30 (35–40); internasal width 19– 23 (25–31); interorbital width 21–26 (28–35); occipital width 13–16 (17–21); body width over pectoral-fin bases 37–60 (49–79); body depth at first dorsal-fin origin 77–97 (99–128); body depth at anal-fin origin 66–88 (85–118); prepelvic length 97–113 (128–153); preanus length 106–123 (141–164); preanal length 123–144 (163–191); isthmus–pelvic distance 41–52 (54–69); isthmus–anus distance 52–61 (68–82); isthmus–anal distance 70–85 (91–113); pelvic–anal distance 28–40 (37–53); anus–anal distance 17–25 (23–33); pelvic-fin length 36–43 (48–57); pectoral-fin length 55–68 (72–90); predorsal length 109– 118 (141–158); height of first dorsal fin 72–87 (95–116); length of first dorsal-fin base 24–31 (31–40); interdorsal length 48–80 (62–102); length of gill slit 25–29 (32–38); length of posterior nostril 2–4 (3–6); barbel length 31–38 (40–50).

Size. To about 31 cm TL ( BSKU 27580 , 306 + mm TL, Okinawa Trough , Japan) .

Variation. In a 14.5 mm HL specimen (NSMT-P 92270; Fig. 204 ), dark spots are serially arranged along the dorsal contour of the trunk and tail. These spots are prominent only when young, and are not found in larger specimens ( Figs. 202–203 ).

Distribution. Restricted to Japan and Taiwan. Known from off the Pacific coasts of Japan northward to Iwaki (Fukushima Pref., 37.00ºN), Okinawa Trough, and northern South China Sea, at depths of 350‾ 755 m (Okamura 1982; Chiou et al. 2004a; Shao et al. 2008a, 2008b; this study; Appendix 3-12E). Uncommon.

Remarks. For further morphological information see Okamura (1982). Ventrifossa longibarbata was originally described from southern Japan, including Tosa Bay (type locality), Suruga Bay, and the Okinawa Trough. One paratype from Suruga Bay, which has been registered at the Zoological Museum of the University of Tokyo (ZMUT), was not found during the author’s visit to the museum in September 2011.

Iwamoto et al. (2015:111) revealed slight differences in counts and measurements between Japanese and Taiwanese populations of V. longibarbata , viz., the interorbital width[21–26.5%HL in the Japanese specimens they examined (21–26% in this study) vs. 25–31% HL in the Taiwanese specimens they examined], postorbital length [39–44% (39–44%) vs. 42–48%], pectoral-fin rays [i21–i26 (i21–i26) vs. i18–i21], and transverse scale rows [below the first dorsal-fin origin 12–14 (10.5–14.5) vs. 7– 12; below the first dorsal-fin midbase 8.5–11.5 (8.5–11.5) vs. 4.5–7.5; and below the second dorsal-fin origin 9–10 (7–9.5) vs. 5–9.5]. These differences may indicate that the Taiwanese population represents a different species.

Relationships and comparisons. Ventrifossa longibarbata readily differs from other Japanese species of the subgenus Ventrifossa by having higher counts of transverse scale rows below the first dorsal-fin midbase (8.5–11.5 vs. ±7.5). This species is unlikely to be confused with any sympatric congeners when young owing to having prominent dark spots dorsally on the trunk and tail ( Fig. 204 vs. absent). It further differs from V. rhipidodorsalis Okamura, 1984 in having a larger orbit (34–39% HL vs. 29–35%) and a longer chin barbel (31– 38% HL vs. 16–26%); and from V. saikaiensis Okamura, 1984 in smaller dimensions of the orbit–preopercle distance (37–43% HL vs. 42–46), snout width (27–30% HL vs. 30–40%), internasal width (19–23% HL vs. 23– 30%), and interorbital width (21–26% HL vs. 26–33%). Ventrifossa longibarbata appears to be most similar to V. garmani ( Jordan & Gilbert in Jordan & Starks, 1904), but is distinguished from the latter in having a narrower interorbital space (21–26% HL vs. 27–33%), a longer chin barbel (31–38% HL vs. 20–33%), and needle-like spinules on the body scales ( Fig. 205 A–B vs. broadly triangular, Fig. 198 ).

Figures

FIGURE 198. Scanning electron micrographs showing a body scale (from the dorsum below the interdorsal space) of Ventrifossa garmani. BSKU 101604, 41.8 mm HL. (A) View from above; (B) oblique view. [Photos: N. Nakayama]

FIGURE 202. Fresh specimens of Ventrifossa longibarbata. (A) BSKU 109021, 26.9 mm HL, 141+ mm TL, west of Okikasayama Bank, Okinawa Trough, East China Sea, 499–504 m depth; (B) BSKU 77922, 35.1 mm HL, 188+ mm TL, south of Muroto, Kochi Pref., Pacific, 414–513 m depth. Lateral views. [Photos: N. Nakayama]

FIGURE 203. Holotype of Ventrifossa longibarbata. BSKU 29494, 49.7 mm HL, 279+ mm TL, Tosa Bay, Kochi Pref., Pacific, 605 m depth. (A) Lateral view; (B) dorsal and (C) ventral views of the head and trunk. Preserved condition. [Photos: N. Nakayama]

FIGURE 204. Preserved juvenile specimen of Ventrifossa longibarbata. NSMT-P 92270, 14.4 mm HL, 84+ mm TL, off Miyagi Pref., Pacific. Lateral view. [Photo: N. Nakayama]

FIGURE 205. Scanning electron micrographs showing body scales (from the dorsum below the interdorsal space) of three species of Ventrifossa. (A–B) V. longibarbata, BSKU 27124, 55.4 mm HL; (C–D) V. rhipidodorsalis, BSKU 27146, paratype, 54.5 mm HL; (E–F) V. saikaiensis, BSKU 28006, paratype, 51.2 mm HL. (A, C, E) Views from above; (B, D, F) oblique views. [Photos: NSMT]