Ventrifossa misakia, : Okada & Matsubara, 1938

Nakayama, Naohide, 2020, Grenadiers (Teleostei: Gadiformes: Macrouridae) of Japan and adjacent waters, a taxonomic monograph, Megataxa 3 (1), pp. 1-383 : 301-305

Ventrifossa misakia ( Jordan & Gilbert in Jordan & Starks, 1904)

[Japanese name: Misaki-sokodara]

( Figs. 201 B–H, 209–212; Table 14 ; Appendix 3-13A)

Coryphaenoides misakius Jordan & Gilbert in Jordan & Starks, 1904:611, unnumbered fig. (original description; holotype: CAS-SU 8107, from Sagami Bay off Misaki; 10 paratypes from Sagami Bay); Jordan et al. 1913:415, fig. 385 (listed; Japan; new Japanese name: “Misaki-sokodara”); Jordan & Thompson 1914:306 (2 spec. from Misaki; FMNH 57091); Kamohara 1938:72 (1 spec. from Kochi Pref.); Kamohara 1950:279 (listed; Kochi and Wakayama Pref.); Matsubara et al. 1951:42 (listed; Mie Pref.); Kuroda 1951:391 (listed; Suruga Bay); Kamohara 1952:98 (spec. from Kochi Pref.); Kuroda 1952:176 (1 spec. from Suruga Bay).

Macrourus asper (not G̹nther 1877): Jordan & Thompson 1914:306, pl. XXXVIII, fig. 2 (2 spec. from Misaki) .

Lionurus misakius: Gilbert & Hubbs 1916:194 (new combination; 1 spec. without precise locality data).

Ventrifossa misakia: Okada & Matsubara 1938:452 (in key; Japan); Matsubara 1955:1315 (in key; Japan); Kamohara 1958:74 (listed; Kochi Pref.); Okada et al. 1959:83 (listed; Kumanonada); Kamohara 1964:96 (listed; Kochi Pref.); Matsubara 1965:508 (compiled; Japan); Okamura 1970a:78, pl. VI, textfig. 35 (description; biological notes; 47 spec. from Pacific off southern Japan from Choshi to Mimase); Okamura 1970b: table 1 (listed; Japan); Kataoka & Tomida 1981:78 (listed; Mie Pref.); Tominaga & Uyeno 1981:489 (listed; Japan); Ohta 1983: table A (listed; Suruga Bay); Akazaki 1984:265 (listed; Aoshima, Miyazaki Pref.); Iwamoto 1990:304, fig. 684 (synopsis); Nakabo 1993:359 (in key; Japan); Shinohara et al. 1996:170 (5 spec. listed from Pacific off Tohoku); Sazonov & Shcherbachev 1997:529 (Kyushu-Palau Ridge; V. fusca a junior synonym of V. misakia ); Shinohara & Matsuura 1997:292 (listed; Suruga Bay); Nakabo 2000:423 (in key; Japan); Shinohara et al. 2001:306 (1 spec. listed from Tosa Bay); Nakabo 2002:423 (in key; Japan); Yoda et al. 2002:11 (listed; East China and Yellow Seas); Shinohara et al. 2005:418 (listed; Ryukyu Islands); Suetsugu & Ohta 2005: table 3 (listed; Enshu-nada); Senou et al. 2006:421 (listed; Sagami Sea); Shinohara & Williams 2006:551, fig. 2-M (listed; Sagami Sea); Kitagawa et al. 2008:38, unnumbered fig. (brief description; spec. from Pacific off Tohoku); Shinohara et al. 2009:709 (5 spec. listed from Pacific off Tohoku); Nakabo & Kai 2013:499 (in key; Japan); Iwamoto et al. 2015:112, fig. 29 (brief description; 6 spec. from South China Sea; other spec. from Japan); Iwatsuki et al. 2017:32 (listed; Hyuganada); Motomura 2020:39 (listed; Japan).

Coryphaenoides asper (not G̹nther 1877): Kuroda 1965 (brief description; 1 spec. from Suruga Bay) [re-identified here from description].

Ventrifossa fusca Okamura, 1982:153 , fig. 93 (original description; holotype: BSKU 26067, from Kyushu-Palau Ridge, 27º55ʹN, 134º39ʹE, in 700 m; 3 paratypes collected with holotype; new Japanese name: “Karasu-hige”); Okamura 1984b:93, pl. 81, fig. B (compiled); Okamura 1988:93, pl. 81, fig. B (compiled); Nakabo 1993:358 (in key; Japan); Okamura 1997:128, fig. 13 (compiled); Nakabo 2000:422 (in key; Japan); Nakabo 2002:422 (in key; Japan); Suetsugu & Ohta 2005: table 3 (listed; Enshu-nada); Senou et al. 2006:421 (listed; Sagami Sea); Nakabo & Kai 2013:498 (in key; Japan).

Ventrifossa garmani (not Jordan & Gilbert 1904): Kitagawa et al. 2008:39, unnumbered fig. (brief description; spec. from Pacific off Tohoku) [re-identified here from figure].

Diagnosis. Second spinous ray of first dorsal fin weakly serrated along its leading edge; first dorsal and anal fins uniformly dusky to dark; front of premaxillary ascending process usually pale; lining of oral cavity pale; head ridges not marked with black; body uniformly pale to dark; snout moderately high, protruding distinctly beyond upper jaw, preoral length 20–26% 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 dorsal-fin base not enlarged; body scales very small, transverse scale rows below midbase of first dorsal fin 7.5–11, below second dorsal-fin origin 8–10; longitudinal scales 58–73; no spinuleless scales posterior to first dorsal-fin base; 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 13–16, outer gill rakers on second arch 12–16; orbit large, greatest diameter 29–40% HL; upper-jaw length 37–42% HL; interorbital space broad, width 28–33% HL; chin barbel short, length 3–7% HL; pectoral-fin length 48–64% HL.

Material examined. 36 specimens. Holotype of Coryphaenoides misakius: CAS-SU 8107 (67.5 mm HL, 334+ mm TL), Misaki , Kanagawa Pref., Sagami Bay, Japan, coll. D.S. Jordan and J.O. Snyder, 1900 . Paratypes of C. misakius: CAS-SU 69810 (4, 59.5–72.6 mm HL, 291+–349+ mm TL, counts and measurements taken on 2 of 4), collected with holotype ; USNM 51421 (4, ca. 61–76.2 mm HL, 210+–371+ mm TL), off Misaki , Sagami Bay, hook and line, coll. D.S. Jordan et al., date unknown . Holotype of Ventrifossa fusca: BSKU 26067 (112 mm HL, 521+ mm TL), Kyushu-Palau Ridge , Japan, 27.9167ºN, 134.6500ºE, 700 m, F/ Vs Shinsei-maru, No. 53 and Kyoyo-maru, No. 2, sta. 2-3, bottom trawl, coll. Y. Kobayashi et al., 20 Feb. 1978. Paratypes of V. fusca: BSKU 26115 (1, 477+ mm TL, heavily damaged), Kyushu-Palau Ridge , 27.9033ºN, 134.6583ºE, 700 m , F/ Vs Shinsei-maru, No. 53 and Kyoyo-maru, No. 2, sta. 2- 4, bottom trawl, coll. Y. Kobayashi et al., 20 Feb. 1978; BSKU 26068 (1, 98.2mm HL, 485+ mm TL), BSKU 26069 (1, 106 mm HL, 455+ mm TL) , collected with holotype. Non-types: Japan: HUMZ 95098 (1, 103 mm HL, 628+ mm TL), west of Amami-oshima, Okinawa Trough , 28.5250ºN, 128.1567ºE, 760–795 m , coll. K. Amaoka, 6 Nov. 1981; BSKU 99072 (1, 25.3 mm HL, 147+ mm TL), Tosa Bay , 33.1950ºN, 133.6783ºE, 528–537 m , FRV Kotaka-maru, otter trawl, 13 May 1997; BSKU 98219 (1, 57.6 mm HL, 279+ mm TL), BSKU 98220 (1, 57.1 mm HL, 289+ mm TL), BSKU 98221 (1, 56.0 mm HL, 268+ mm TL), BSKU 98222 (1, 54.9 mm HL, 262+ mm TL), Tosa Bay , 33.1428ºN, 133.6248ºE, 450–490 m , FRV Kotaka-maru, otter trawl, 1 Aug. 1988; BSKU 44127 (1, 46.4 mm HL, 224+ mm TL), Tosa Bay , 450–500 m , FRV Kotaka-maru, otter trawl, 5 Oct. 1987; * BSKU 77920 (1, 58.8 mm HL, 274+ mm TL), * BSKU 77921 (1, 22.7 mm HL, 131+ mm TL), * BSKU 78801 (1, 36.9 mm HL, 171+ mm TL), * BSKU 78807 (1, 21.6 mm HL, 125+ 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; NSMT-P 93115 (1, 61.8 mm HL, 311+ mm TL), NSMT-P 93116 (1, 63.2 mm HL, 303+ mm TL), NSMT-P 93117 (1, 66.3 mm HL, 332+ mm TL), NSMT-P 93118 (1, 55.5 mm HL, 235+ mm TL), off Ohsima Island, Izu Islands , R/ V Tansei-maru, cr. KT-07-31, sta. L-3-500 , coll. T. Kuramochi, date unknown; BSKU 83754 (1, 54.6 mm HL, 286+ mm TL), off Fukushima, 450 m , FRV Wakataka-maru, sta. F2, coll. H. Endo, 6 Oct. 1997; BSKU 83755 (1, 44.8 mm HL, 226+ mm TL), off Fukushima, 350 m , FRV Wakataka-maru, sta. F12, coll. H. Endo, 6 Oct. 1997; BSKU 116162 (1, 37.7 mm HL, 192+ mm TL), off Minami-soma , 37.4878ºN, 141.8532ºE, 411–419 m , FRV Wakataka-maru, sta. 42 (H-400), coll. H. Endo, 3 Nov. 1995; BSKU 83757 (1, 34.1 mm HL, 166+ mm TL), off Onahama , 350 m , FRV Wakataka-maru, sta. G, coll. H. Endo, 16 Oct. 1997; BSKU 83734 (1, 56.4 mm HL, 258+ mm TL), BSKU 83741 (1, 58.7 mm HL, 311+ mm TL), BSKU 83744 (1, 55.9 mm HL, 286+ mm TL) , BSKU 83747 (1, 61.0 mm HL, 311+ mm TL), off Mito, 450 m, FRV Wakataka-maru, sta. H2, coll. H. Endo, 9 Oct. 1997.

Counts and measurements. See Table 14 .

Size. Attains 63 cm TL ( HUMZ 95098, 628 mm TL, Okinawa Trough , Japan) .

Distribution. Restricted to Japan and Taiwan.Known from off the Pacific coasts of Japan northward to the Oshika Peninsula (38.32ºN), Okinawa Trough, northern South China Sea, and Kyushu-Palau Ridge, at depths of 202‾ 795 m (Iwamoto et al. 2015; this study; Appendix 3-13A). Common in the south of Choshi (35.74ºN; Chiba Pref.), but seemingly rare in other parts of its range.

Remarks. For a full description see Okamura (1970a). Ventrifossa misakia was originally described from Sagami Bay, Japan ( Jordan & Gilbert in Jordan & Starks 1904; as a species of Coryphaenoides Gunnerus, 1765 ).The original description was based on 11 specimens ( Fig. 210 ), two of which (from Albatross sta. 3695) were not found among the CAS and USNM collections.

Records of “ Macrourus asper ” (G̹nther, 1877) by Jordan & Thompson (1914:306, pl. XXXVIII, fig. 2) and V. garmani ( Jordan & Gilbert in Jordan & Starks, 1904) by Kitagawa et al. (2008:39, unnumbered fig.) can be referred to as V. misakia , according to their figures that clearly depict characteristic physiognomy of the latter species. Okamura (1984a) reported V. misakia from the Okinawa Trough, but his specimen was re-identified as V. johnboborum Iwamoto, 1982 (see the Remarks of the latter species).

Nomenclatural discussion. Okamura (1982) described V. fusca based on four large specimens (98.2– 112 mm HL, 455+–521+ mm TL; Figs. 211–212 ) collected from the Kyushu-Palau Ridge, considering this species most similar to “ V. macronema ” (Smith & Radcliffe in Radcliffe, 1912). However, the latter species is currently classified in the genus Kuronezumia Iwamoto, 1974 (see Shcherbachev et al. 1992), and is quite different from V. fusca in many aspects. A close similarity between V. fusca and V. misakia was first recognized by Iwamoto (1990:305), who wrote that “no sharp differences are apparent” to distinguish the two species. In his key to species of the genus ( Iwamoto 1990:295), V. fusca is distinguished from V. misakia by subtle differences in coloration of the body (dark vs. medium brown) and fins (blackish vs. dusky to pale). He (1990) also noted that V. fusca has a scaly patch on the gular membrane (vs. absent in V. misakia ) and more spinules on the body scales as compared with V. misakia . Subsequently, Sazonov & Shcherbachev (1997) considered that these differences are attributable to size-related variations, and do no warrant their specific separation; V. fusca was therefore synonymized with V. misakia in their study. However, subsequent authors tentatively treated V. fusca as a valid species ( Iwamoto & Merrett 1997; Nakabo 1993, 2000, 2002; Iwamoto & Williams 1999; Nakabo & Kai 2013). Most recently, Iwamoto et al. (2015) followed Sazonov & Shcherbachev (1997) in regarding this species as a junior synonym of V. misakia .

An examination of the type series of V. misakia and V. fusca , along with many additional specimens from Japan, reconfirmed the conspecificity of these two nominal species. Firstly, all counts and measurements of the type specimens of V. fusca generally lie within (or greatly overlap with) the range of variation for V. misakia ( Table 14 ); thus, they cannot be distinguished by meristic and morphometric characters. Secondly, as noted by Iwamoto (1990), the body scales of V. fusca ( Fig. 201F, H ) are covered with more spinules as compared with the type specimens of V. misakia , but the number of spinules tends to increase with growth in the latter species ( Fig. 201 B–E, G). Considering the large body size of the type specimens of V. fusca (98.2–112 mm HL, 455+–521+ mm TL), the differences in the scale spinulation can be attributed to ontogenetic variation. A large additional specimen of V. misakia collected from the Okinawa Trough (HUMZ 95098, 103 mm HL), which is almost equal in size to the paratypes of V. fusca , has similarly numerous spinules on the body scales ( Fig. 201G ). Thirdly, the holotype of V. fusca is readily distinguished from V. misakia by having a small scaly patch on the gular membrane, but this feature is not found in the paratypes of this species. The presence/absence of the scales on the gular membrane is likely intraspecific variation. Fourthly, Iwamoto (1990) distinguished V. fusca from V. misakia in having darker coloration ( Fig. 211 ), but Fig. 209 shows that the body and fins of V. misakia become darker with increasing size. Sazonov & Shcherbachev (1997) also reported that an additional specimen from the Kyushu-Palau Ridge (type locality of V. fusca ) had significantly paler color than the type specimens of this species. Therefore, the differences in coloration can be attributed to ontogenetic or geographical variation. Finally, the holotype of V. fusca differs from V. misakia in that the mandibular teeth are arranged in two distinct series laterally (vs. 2–3 irregular series or a narrow band), with the inner series distinctly enlarged (Okamura 1982: fig. 93B vs. slightly enlarged). In their keys to species of Japanese grenadiers, Nakabo (1993, 2000, 2002) and Nakabo & Kai (2013) separated the two species based on this character. However, in the paratypes of V. fusca , the mandibular teeth are arranged in 2–3 irregular series, and the size of the teeth becomes progressively larger inwardly. The unique dentition of the holotype of V. fusca is herein referred to individual variation. This difference might be attributable to the larger body size of this specimen, which is by far the largest among the available materials for the two nominal species. Accordingly, there are no reasons to doubt their conspecificity, and V. fusca is re-confirmed here as a junior synonym of V. misakia .

Relationships and comparisons. According to Sazonov & Iwamoto (1992:80), V. misakia is most closely related to V. johnboborum Iwamoto, 1982 . These species are distinguished from each other by the combination of the barbel length, internasal width, and coloration of the oral cavity (see the Relationships and comparisons of the latter species). They differ from other Japanese species of Ventrifossa in having a small but prominent scute on the tip of the snout (vs. absent), smaller body scales (longitudinal scales Ż58 vs. ±56), a shorter barbel [±16% HL (usually ±12%) vs. Ż16%], and a longer preoral [Ż19% HL (usually Ż20%) vs. ±22% (usually ±19%)]. The two species also differ from the other Japanese congeners in that the suborbital shelf is abruptly and greatly constricted anteriorly (vs. moderately deep).

Figures

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]

FIGURE 209. Fresh specimens of Ventrifossa misakia. (A) BSKU 77921, 22.7 mm HL, 131+ mm TL, south of Muroto, Kochi Pref., Pacific, 414–513 m depth; (B) BSKU 77920, 58.8 mm HL, 274+ mm TL, collected with BSKU 77921; (C) BSKU 83747, 61.0 mm HL, 311+ mm TL, off Mito, Ibaraki Pref., Pacific, 450 m depth; (D) HUMZ 95098, 103 mm HL, 628+ mm TL, west of Amami-oshima Island, Kagoshima Pref., Okinawa Trough, East China Sea, 760–795 m depth. Lateral views. [Photos: (A–B) N. Nakayama; (C) BSKU; (D) HUMZ]

FIGURE 210. Holotype of Coryphaenoides misakius (= Ventrifossa misakia). CAS-SU 8107, 67.5 mm HL, 334+ mm TL, Misaki, Kanagawa Pref., Sagami Bay, Pacific. (A) Lateral view; (B) dorsal and (C) ventral views of the head and trunk. Preserved condition. [Photos: N. Nakayama]

FIGURE 211. Fresh specimen of Ventrifossa misakia. BSKU 26067, holotype of V. fusca, 112 mm HL, 521+ mm TL, Kyushu- Palau Ridge, Pacific, 700 m depth. Lateral view. [Photo: BSKU]

FIGURE 212. Preserved specimen of Ventrifossa misakia. BSKU 26067, holotype of V. fusca, 112 mm HL, 521+ mm TL, Kyushu- Palau Ridge, Pacific, 700 m depth. (A) Lateral, (B) dorsal, and (C) ventral views. [Photos: N. Nakayama]