Ventrifossa johnboborum Iwamoto, 1982

Nakayama, Naohide, 2020, Grenadiers (Teleostei: Gadiformes: Macrouridae) of Japan and adjacent waters, a taxonomic monograph, Megataxa 3 (1), pp. 1-383 : 289-294

Ventrifossa johnboborum Iwamoto, 1982

[New Japanese name: Sumikui-sokodara]

( Figs. 199–200 , 201A ; Table 14 ; Appendix 3-12D)

Ventrifossa johnboborum Iwamoto, 1982:55 , fig. 1 (original description; holotype: AMS I. 15602-002, collected from mouth of Diceratias bispinosus , floating at surface near Papua New Guinea, Bismarck Sea ; 1 paratype from Philippines and 2 non-types from South China Sea).

Ventrifossa misakia (not Jordan & Gilbert in Jordan & Starks 1904): Okamura 1984a:213, 361, fig. 149 (brief description; 1 spec. from Okinawa Trough; BSKU 28595); Okamura 1984b:93, pl. 344, fig. J (compiled); Okamura 1988:93, pl. 344, fig. J (compiled).

Diagnosis. Second spinous ray of first dorsal fin weakly serrated along its leading edge; first dorsal and anal fins uniformly dusky to dark; small black spot present on front of premaxillary ascending process; lining of oral cavity intensely black; head ridges not marked with black; body uniformly pale to dark; snout moderately high, protruding distinctly beyond upper jaw, preoral length 19–25% HL; small, stout, 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 very small, transverse scale rows below midbase of first dorsal fin 10–13, below second dorsal-fin origin 8.5–11; longitudinal scales 60– 72; area of spinuleless scales posterior to first dorsal-fin base almost absent or only narrowly developed; outer series of premaxillary teeth slightly enlarged; mandibular teeth arranged in narrow tapered band; suborbital shelf abruptly narrowing anteriorly; inner gill rakers on first arch 12–15, outer gill rakers on second arch 11–14; orbit large, greatest diameter 30–38% HL; upper-jaw length 36–41% HL; interorbital space broad, width 26–30% HL; chin barbel short, length 9–16% HL; pectoral-fin length 52% HL.

Material examined. 9 specimens. Holotype of Ventrifossa johnboborum: AMS I. 15602-002 (85.3 mm HL, 365+ mm TL), Bismarck Sea, floating at surface near Tanga Island, Papua New Guinea (in mouth of ceratioid anglerfish Diceratias bispinosus ), 30 Apr. 1967. Nontypes: Japan: BSKU 28595 (1, 47.9 mm HL, 222+ mm TL), northwest of Amami-oshima Island, Okinawa Trough, 29.9500ºN, 128.0000ºE, 585–610 m, F/V Ryoanmaru, No. 28, tr. 76, bottom trawl, coll. Y. Kinoshita and S. Hagino, 20 Mar. 1978. Southwestern Pacific: CAS 90669 (1, 95.6 mm HL, 468+ mm TL), Norfolk Ridge, 24.6923ºS, 168.6813ºE, 800–1240 m, HALIPRO 2, sta. BT 64, coll. T. Iwamoto et al., 19 Nov. 1996; CAS 90672 (3, 78.5–97.2 mm HL, 337+–461+ mm TL), Norfolk Ridge, 24.6938ºS, 168.6497ºE, 720–1048 m, HALIPRO 2, sta. BT 62, coll. T. Iwamoto et al., 18 Nov. 1996; CAS 86488 (1, 46.6 mm HL, 243+ mm TL), New Caledonia, 23.1164ºS, 166.8533ºE, 825 m, BIOCAL, sta. CP 32, 29 Aug. 1985; CAS 90665 (1, 81.4 mm HL, 412+ mm TL), Lord Howe Rise, 24.2803ºS, 161.7508ºE, 970–1063 m, HALIPRO 2, sta. BT 101, coll. T. Iwamoto et al., 26 Nov. 1996; CAS 86457 (1, 41.7 mm HL, 152+ mm TL), east of Bellona Plateau, 21.0150ºS, 160.8383ºE, 745–825 m, MUSORSTOM 5, sta. CC 390, 22 Oct. 1986.

Counts and measurements. See Table 14 .

Size. Attains about 48 cm TL ( Sazonov & Iwamoto 1992; Iwamoto & Williams 1999; Iwamoto & Graham 2001).

Distribution. Widely distributed in the Indian and Pacific Oceans, including the Philippines, South China Sea, New Caledonian region, Australia (WesternAustralia, Queensland, and New South Wales), and Sala y Gomez Ridge, at depths of about 400–1100 m ( Iwamoto 1982; Sazonov & Iwamoto 1992; Iwamoto & Merrett 1997; Sazonov & Shcherbachev 1997; Iwamoto & Williams 1999; Merrett & Iwamoto 2000; Iwamoto & Graham 2001; Last et al. 2014). The Japanese record is based on a single specimen collected from the Okinawa Trough in 585–610 m (Appendix 3-12D). Rare in the northwestern Pacific, but common in the Southern Hemisphere.

Remarks. This species has been adequately described by previous authors, and there is no need for repetition here. For further morphological details see the original description given by Iwamoto (1982). Sazonov & Iwamoto (1992) also provided an excellent description of the species, based on the holotype and additional specimens from the southeastern Pacific.

Ventrifossa johnboborum was originally described on the basis of the holotype collected from the Bismarck Sea (type locality; Fig. 199 ), and three other specimens (not designated as paratypes) from the Philippines and South China Sea, of which a Philippines specimen was previously reported as V. misakia Jordan & Gilbert in Jordan & Starks, 1904 by Gilbert & Hubbs (1920). Subsequently, it has been widely recorded from the Southern Hemisphere, viz., the Freda Seamount in the western Indian Ocean ( Shcherbachev 1987), west and east coasts of Australia ( Iwamoto & Williams 1999; Iwamoto & Graham 2001), New Caledonian region ( Iwamoto & Merrett 1997; Merrett & Iwamoto 2000), and Sala y Gomez Ridge in the southeastern Pacific ( Sazonov & Iwamoto 1992). However, pronounced geographic variations in several counts and measurements, including pelvic-fin rays, gill rakers, barbel length, upper-jaw length, and pelvic–anal distance, are also known within the species ( Sazonov & Iwamoto 1992; Iwamoto & Merrett 1997; Sazonov & Shcherbachev 1997).A further study is therefore necessary to elucidate the taxonomic status of each population of V. johnboborum (see also Iwamoto & Graham 2001).

TABLE 14. (Continued)

Based on a single specimen collected from the Okinawa Trough in the East China Sea (BSKU 28595, 47.9 mm HL, 222+ mm TL; Fig. 200 ), Iwamoto et al. (2015) newly recorded V. johnboborum from Japan. This specimen was previously identified as V. misakia by Okamura (1984a). The new standard Japanese name, “Sumikui-sokodara”, is derived from the species’ characteristic black oral cavity (= sumikui) and a Japanese name for grenadiers (= sokodara ).

Relationships and comparisons. According to Sazonov & Shcherbachev (1997), V. johnboborum closely resembles V. misakia distributed in the northwestern Pacific from Japan to Taiwan, and V. nasuta ( Smith, 1935) known from the southwestern Indian Ocean, and they comprise the subgenus Sokodara Iwamoto, 1979 . Ventrifossa johnboborum differs notably from V. nasuta in having higher counts of transverse scale rows (15–21 vs. 7–9 below the first dorsal-fin origin; 10–13 vs. 6–7 below the first dorsal-fin midbase; and 8.5–11 vs. 5.5–7.5 below the second dorsal-fin origin) and a shorter chin barbel (9–16% HL vs. 16–23%) [data for V. nasuta are from Sazonov & Shcherbachev (1997: table 2)]. On the other hand, this species is readily distinguished from V. misakia by its uniformly black oral cavity (vs. pale) and the presence of a small black spot on the front of the premaxillary ascending process (vs. usually absent). It further differs from that species in having a longer chin barbel (9–16% HL vs. 3–7%) and a narrower internasal space (21–23% HL vs. 24–29%).

Figures

FIGURE 199. Holotype of Ventrifossa johnboborum. AMS I.15602-002, 85.3 mm HL, 365+ mm TL, floating at the surface near Tanga Island, Papua New Guinea, Bismarck Sea (in a mouth of the ceratioid anglerfish Diceratias bispinosus). (A) Lateral view; (B) dorsal and (C) ventral views of the head and trunk. Preserved condition. [Photos: N. Nakayama]

FIGURE 200. Preserved specimen of Ventrifossa johnboborum. BSKU 28595, 47.9 mm HL, 222+ mm TL, northwest of Amamioshima Island, Kagoshima Pref., Okinawa Trough, East China Sea, 585–610 m depth. (A) Lateral view; (B) dorsal and (C) ventral views of the head and trunk. [Photos: N. Nakayama]

FIGURE 201. Scanning electron micrographs showing body scales (from the dorsum below the interdorsal space) of (A) Ventrifossa johnboborum and (B–H) V. misakia. (A) BSKU 28595, 47.9 mm HL; (B) BSKU 78801, 36.9 mm HL; (C) BSKU 78807, 21.6 mm HL; (D) BSKU 98219, 57.6 mm HL; (E) NSMT-P 93117, 66.3 mm HL; (F) BSKU 26068, paratype of V. fusca, 98.2 mm HL; (G) HUMZ 95098, 103 mm HL; (H) BSKU 26067, holotype of V. fusca, 112 mm HL. Views from above. [Photos: N. Nakayama]