Nezumia proxima, : Okamura, 1970

Nakayama, Naohide, 2020, Grenadiers (Teleostei: Gadiformes: Macrouridae) of Japan and adjacent waters, a taxonomic monograph, Megataxa 3 (1), pp. 1-383 : 250-255

Nezumia proxima (Smith & Radcliffe in Radcliffe, 1912)

[Japanese name: Higo-sokodara]

( Figs. 168–170 ; Table 12 ; Appendix 3-10C)

Macrurus altipinnis (not G̹nther 1877): G̹nther 1887:138 (brief description; in part, BMNH 1887.12.7.92; Enshu-nada).

Macrourus nasutus (not G̹nther 1877): Jordan & Gilbert in Jordan & Starks 1904:614 (in part, 1 spec. from off Izu; see Gilbert & Hubbs 1916:201).

[?] Macrourus rudis (not G̹nther 1887): Franz 1910:16 (1 spec. from Aburatsubo); Jordan et al. 1913:417 (listed; Japan; new Japanese name: “Aka-sokodara”).

Macrourus proximus Smith & Radcliffe in Radcliffe, 1912:119, pl. 26, fig. 2 [original description; holotype: USNM 72936 , from Sogod Bay , Philippines, Albatross sta. 5202, 10º12ʹ00ʺN, 125º04ʹ10ʺE, in 502 ftm (918 m)] .

Lionurus proximus: Gilbert & Hubbs 1916:201 [new combination; brief description; in part, 10 spec. from East China Sea, Hyuganada, off Cape Shionomisaki, and Enshu-nada; 1 spec. from Albatross sta. 4918 (CAS-SU 22941) is Nezumia spinosa ]; Okada & Matsubara 1938:453 (in key; Japan); Matsubara 1955:1316 (in key; Japan); Matsubara 1965:509 (compiled; Japan; new Japanese name: “Higo-sokodara”).

Lionurus abei Matsubara, 1943:146 , figs. 7–8 (original description; holotype: FAKU 4909, from Kumano-nada; new Japanese name: “Kasumi-hige”); Matsubara 1955:1317, pl. 134, fig. 458 (in key; Japan); Okada et al. 1959:83 (listed; Kumanonada); Matsubara 1965:509 (compiled; Japan); Kuroda 1966:29 (brief description; spec. from Suruga Bay).

Nezumia proximus: Okamura 1970a:94 , pl. XXI, text-fig. 41 (description; biological notes; 17 spec. from Pacific off southern Japan from Choshi to Kumano-nada and East China Sea); Kuroda 1971:56 [listed from Suruga Bay after Okamura (1970a)].

Nezumia proxima: Okamura 1970b : table 1 (listed; Japan); Kataoka & Tomida 1981:78 (listed; Mie Pref.); Tominaga & Uyeno 1981:489 (listed; Japan); Okamura 1982:163, 351, fig. 162 (brief description; 6 spec. from Tosa Bay; photo based on BSKU 29500); Sawada 1983:107, 192, fig. 58 [brief description; 4 spec. from Pacific off Tohoku; photo based on HUMZ spec. (catalog no. unknown)]; Ohta 1983: table A (listed; Suruga Bay); Okamura 1984a:217, 362, fig. 152 (brief description; 8 spec. from Okinawa Trough; photo based on BSKU 29792); Okamura 1984b:94, pl. 81, fig. I (compiled); Okamura 1988:94, pl.81, fig.I (compiled); Iwamoto 1990:281, fig. 645 (synopsis); Nakabo 1993:360 (in key; Japan); Hori 1996:27 (listed; Ibaraki Pref.); Shinohara et al. 1996:170 (2 spec. listed from Pacific off Tohoku); Okamura 1997:128, fig. 17 (compiled); Shinohara & Matsuura 1997:292 (listed; Suruga Bay); Funabashi 1998:85 (listed; Ibaraki Pref.); Nakabo 2000:424 (in key; Japan); Shinohara et al. 2001:306 (3 spec. listed from Tosa Bay); Nakabo 2002:424 (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); Shao et al. 2008b: table 2 (2 spec. listed from eastern Taiwan and South China Sea; first Taiwanese record); Kitagawa et al. 2008:40, unnumbered fig. (brief description; spec. from Pacific off Tohoku); Shinohara et al. 2009:709 (1 spec. listed from Pacific off Tohoku); Nakabo & Kai 2013:500 (in key; Japan); Iwamoto et al. 2015:93, fig. 19 (brief description; 3 spec. from northeastern and southwestern Taiwan, and South China Sea); Amaoka et al. 2020:159, fig. 213 (erroneously listed from Hokkaido); Motomura 2020:39 (listed; Japan).

[?] Lionurus spinosus (not Gilbert & Hubbs 1916): Maruyama 1971:33 (listed with a question mark; Iwate Pref.).

Diagnosis. A species of Nezumia with 8–10 pelvic-fin rays. Snout moderately long, conical, protruding well beyond upper jaw, length 29–33% HL, ventral contour oblique in lateral view; underside of snout broadly naked; ventral surfaces of head scaled posterior to vertical through midorbit; mandibular rami mostly scaled. Second spinous ray of first dorsal fin not extremely prolonged (height of fin 92–118% HL). Body scales covered with short, greatly reclined, lanceolate spinules in tightly packed convergent rows or densely scattered over exposed portion; tip of last spinule in each row extending well beyond posterior scale margin; middle row of spinules not enlarged; scales below second dorsal-fin origin 6–8.5. Anterior dermal window of light organ (ADW) situated between inner pelvic-fin bases. Cephalic sensory pores present, but barely discernible. Broad dark band encircling trunk (often faint or absent in preserved specimens); first dorsal fin uniformly dark.

Material examined. 34 specimens. Japan: BSKU 99112 (1, 50.4 mm HL, 314+ mm TL), BSKU 99117 (1, 59.5 mm HL, 357+ mm TL), off Pacific coast of Tohoku, FRV Wakataka-maru, sta. 32 (F-800), coll. H. Endo , date unknown; BSKU 26667 (1, 61.7 mm HL, 336+ mm TL), west of Yaku-shima Island, Okinawa Trough , 30.0300ºN, 128.3650ºE, 900 m, F/ V Yuryo-maru, No. 8, tr. 16-1, bottom trawl, coll. Y. Kinoshita and S. Hagino, 3 Feb. 1978 ; BSKU 86874 (1, 31.4 mm HL, 189+ mm TL), off Nobeoka, Hyuga-nada , 32.5163ºN, 132.2175ºE, 997–1030 m, R/ V Tansei-maru, cr. KT-99-18, sta. BT-2, beam trawl, coll. H. Endo and S. Nagatomo, 16 Dec. 1999 ; BSKU 44837 (1, 54.2 mm HL, 319+ mm TL), Tosa Bay , 32.9886ºN, 133.5978ºE, 700–720 m, FRV Kotakamaru, otter trawl, 21 Jun. 1988 ; BSKU 98937 (1, 33.3 mm HL, 197+ mm TL) , BSKU 98938 (1, 47.6 mm HL, 218+ mm TL) , BSKU 98939 (1, 28.4 mm HL, 147+ mm TL), Tosa Bay , 33.0452ºN, 133.6448ºE, 733–740 m, FRV Kotaka-maru, otter trawl, 25 Jan. 1989 ; BSKU 101591 (1, 42.1 mm HL, 254+ mm TL) , BSKU 101592 (1, 49.2 mm HL, 303+ mm TL) , BSKU 101593 (1, 48.0 mm HL, 280+ mm TL) , BSKU 101594 (1, 27.9 mm HL, 176+ mm TL) , BSKU 101595 (1, 33.3 mm HL, 203+ mm TL) , BSKU 101596 (1, 39.9 mm HL, 229+ mm TL) , BSKU 101597 (1, 40.9 mm HL, 253+ mm TL) , BSKU 101598 (1, 35.2 mm HL, 196+ mm TL) , BSKU 101599 (1, 49.9 mm HL, 302+ mm TL), Tosa Bay , 700 m, FRV Kotaka-maru, otter trawl, 22 May 1989 ; BSKU 47166 (1, 37.6 mm HL, 233+ mm TL), off Tosa Bay , 32.8953ºN, 133.6777ºE, 996– 1010 m, R/ V Tansei-maru, cr. KT-89-06, sta. T1, beam trawl, 8 Nov. 1989 ; BSKU 23147 (1, 45.1 mm HL, 274+ mm TL), Tosa Bay , 33.0350ºN, 133.7500ºE, 945 m, FRV Kaiyo-maru, cr. SK-75-2, sta. 18, tr. 3, bottom trawl, 26 Jan. 1975 ; BSKU 23076 (1, 46.7 mm HL, 225+ mm TL) , BSKU 23181 (1, 48.1 mm HL, 291 mm TL), off Kochi, 32.9800ºN, 133.8550ºE, 1043 m, FRV Kaiyo-maru, cr. SK-75-2, sta. 19, tr. 2, bottom trawl, 26 Jan. 1975 ; * KPMNI 28856 (1, 44.8 mm HL, 236+ mm TL), ca. 24 km west-southwest of Shirahama , Wakayama, 33.5795ºN, 135.0995ºE, 532 m, R/ V Tansei-maru, cr. KT-10-16, sta. YK-2, box corer, coll. T. Sato, 15 Aug. 2010 ; BMNH 1887.12 .7.92 (1, 24.0 mm HL, 149+ mm TL), off Cape Omaezaki, Enshu-nada , 34.1167ºN, 138.0000ºE, 565 ftm (1034 m), Challenger sta. 235, trawl, 4 Jun. 1875 ; BSKU 19762 (1, 41.6 mm HL, 211+ mm TL) , BSKU 19764 (1, 57.9 mm HL), Sagami Bay , 35.1167ºN, 139.4500ºE, 730– 790 m, FRV Soyo-maru, sta. T7, 23 Nov. 1966 ; BSKU 20250 (1, 39.2 mm HL, 254+ mm TL), west of Misaki, Sagami Bay , 35.1283ºN, 139.4983ºE, 450 m, FRV Soyomaru, sta. 77, 30 Jun. 1972 ; BSKU 14184 (1, 35.7 mm HL, 221+ mm TL) , BSKU 14186 (1, 29.2 mm HL, 190+ mm TL), off Hiratsuka, Sagami Bay , 35.2522ºN, 139.5178ºE, 510–600 m, R/ V Tansei-maru, coll. O. Okamura, 12 Apr. 1969 ; BSKU 45547 (1, 43.8 mm HL, 264+ mm TL), east of Katsuura , 35.1400ºN, 140.8125ºE, 507–578 m, R/ V Tansei-maru, cr. KT-89-03, sta. TB5, 13 Mar. 1989 ; BSKU 101193 (1, 60.3 mm HL, 374+ mm TL), off Hitachi , 900 m, FRV Wakataka-maru, sta. H, coll. H. Endo, 10 Oct. 1997 ; BSKU 97917 (1, 56.7 mm HL, 345+ mm TL), off Oshika Peninsula , 38.5318ºN, 142.3370ºE, 772–783 m, FRV Wakataka-maru, sta. 32, 28 Oct. 1995 ; BSKU 97906 (1, 58.7 mm HL, 375+ mm TL) , BSKU 97910 (1, 51.4 mm HL, 341+ mm TL), off Otsuchi , 39.1444ºN, 142.3748ºE, 847–935 m, R/ V Tansei-maru, cr. KT-89-03, sta. SR89, 10 Mar. 1989 . Uncertain variant : BSKU 19891 (50.8 mm HL, 274+ mm TL), east-southeast of Miyake-jima Island, Shichito-Iojima Ridge , Japan, 33.9183ºN, 140.0083ºE, 860–870 m, FRV Soyo-maru, beam trawl, 1 Dec. 1968 .

Description of Japanese specimens. General features are shown in Fig. 168 . Counts and measurements are given in Table 12 . Body long, slender, gradually tapering from first dorsal-fin origin to end of tail. Trunk short, laterally compressed, width over pectoral-fin bases 1.3–1.7 in depth below first dorsal-fin origin. Head short, HL about 5.2–6.6 in TL, its dorsal profile almost straight from tip of snout to nape. Snout moderately long, protruding well beyond upper jaw, conical in lateral view, bluntly pointed in dorsal view; snout length 0.9–1.1 times as long as orbit diameter; ventral contour oblique, forming angle of about 45º to horizontal axis of head and body; tip of snout situated on horizontal through midorbit. Orbit moderately large, circular, greatest diameter 1.1–1.9 in postorbital length. Interorbital space almost flat, width 1.3–1.7 in orbit diameter. Mouth small, inferior, upperjaw length 0.9–1.2 in orbit diameter; posterior margin of maxilla extending beyond vertical through midorbit; lateral corner of mouth slightly restricted by lip folds; lips thick, fleshy, papillose near tooth bands. Suborbital region narrow, divided into upper and lower halves by infraorbital ridge. Preopercle large, broadly rounded ventrally, posterior margin slightly inclined from vertical; preopercular ridge low, poorly marked, forming slight backward extension at angle. Interopercle narrowly exposed beyond preopercle. Gill membranes broadly connected across, and attached mesially to isthmus, with broad posterior free fold. Anteroventral end of gill opening not reaching below posterior margin of lower jaw. Outermost gill slit moderately restricted by skin folds, length 2.0– 2.8 in orbit diameter. Gill rakers small, tubercular, armed with short, fine spines distally; those on outer side of first arch and inner side of fourth arch much smaller than others. Gill filaments moderately long. Barbel well developed, length 1.4–2.1 in orbit diameter.

Anus closer to pelvic-fin bases than to anal-fin origin. Periproct broad, oval in shape. Anterior dermal window of light organ small, circular, situated between inner bases of pelvic fins.

Teeth short, slender, sharp, in broad tapered bands in both jaws. Premaxillary teeth arranged in about 5 tooth rows near symphysis, with outermost series distinctly enlarged. Mandibular band similar to that of premaxillary, with about 6 tooth rows at widest point near symphysis, but none significantly enlarged. Posterior ends of tooth bands falling short of lateral corner of mouth in both jaws. All teeth deeply embedded in thick layer of gum papillae.

Body scales small, thin, moderately deciduous, covered with short, greatly reclined, lanceolate spinules in tightly packed convergent rows or densely scattered over exposed portion ( Fig. 169 A–B); tip of last spinule in each row extending well beyond posterior scale margin; middle row of spinules not enlarged; buttresses of spinules absent; reticulate structure narrowly developed on posterior parts of unexposed portion. Body fully scaled except for fins, periproct, and dermal window of light organ; pelvic fins mostly naked, but basal portions covered with tiny scales.

Suborbital shelf formed of 2 rows of stout, coarsely modified scales. Snout tipped with 2 enlarged, thickened, closely adjoined tubercles; scales on lateral angles of snout modified into scute-like scales. Scales on head generally similar to those on body, except that spinules more erect and arranged in subparallel rows. Dorsal and lateral surfaces of head almost fully scaled; membrane around anterior nostril and paired Y-shaped areas dorsally posterior to leading edges of snout narrowly naked. Underside of snout almost completely naked; lower half of suborbital region mostly scaled, but narrowly naked above upper lip; anterior 1/3–1/2 of mandibular rami naked; gular and branchiostegal membranes lacking scales.

Cephalic sensory pores present, arranged along sensory canals; those on underside of head very slightly enlarged, more or less tubular. Free neuromasts small, tubercular, densely scattered on underside of snout and mandibular rami; similar but much smaller neuromasts serially arrayed along leading edges of snout, supranarial ridges, suborbital shelf, and supraorbital canals. Grooved lateral line incomplete anteriorly, occurring as short interrupted segments, but complete posterior to vertical through midbase of first dorsal fin.

Origin of first dorsal fin slightly posterior to vertical through pectoral- and pelvic-fin bases, the latter two on about same vertical; first dorsal fin high, its height 3.2–4.7 times as long as its base length; second spinous ray long, but not especially elongate, armed along its leading edge with short, reclined, conical denticles; its tip extending to bases of 4th–20th second dorsal-fin rays when laid back. Second dorsal fin well separated from first dorsal, originating above 5th–13th anal-fin rays; interdorsal space 1.1–2.4 times as long as first dorsal-fin base length. Outermost pelvic-fin ray slightly prolonged, hair-line distally, its tip usually extending beyond anal-fin origin when laid back.

Color when fresh ( Fig. 168 ). Uniformly dark brown; broad dark band encircling trunk (especially prominent when body scales mostly missing; Fig. 168C ).

Color in alcohol. Similar to that in fresh specimens; head and body dark brown overall, with broad dark band encircling trunk (band often indistinct in old specimens); abdomen and gill cover prominently darker in smaller specimens; lips dark; oral cavity blackish except for pale gums; gill cavity mostly black, but paler on ceratohyal, epihyal, and anterior to lower end of cleithrum; gill rakers and arches dark dusky, filaments pale; chin barbel varying from pale to dark; gular membrane blackish, but abruptly pallid laterally; branchiostegal membranes black, especially along distal margins; fins uniformly dark.

Size. To about 40 cm TL ( NSMT-P 94347 , 398 + mm TL, off Hitachi , Ibaraki Pref., Japan) .

Distribution. Distributed in the western Pacific from the Philippines to Japan ( Radcliffe 1912; Gilbert & Hubbs 1920; Shao et al. 2008b; this study). In Japanese waters, known from off the Pacific coasts northward to Kuji (40.19ºN; Iwate Pref.) and the Okinawa Trough at depths of 361‾ 1348 m (Appendix 3-10C). Common, especially in the Pacific off Honshu north of Choshi (35.74ºN; Chiba Pref.).

Remarks. Nezumia proxima was originally described from the Philippines, and first recorded from Japan by Gilbert & Hubbs (1916). Matsubara (1943) described N. abei (as a species of Lionurus G̹nther, 1887) from a single specimen collected from the Kumano-nada, Japan, but this species has been regarded as a junior synonym of N. proxima (e.g., Okamura 1970a; Iwamoto 1990; Iwamoto et al. 2015). Unfortunately, the holotype of N. abei is presumed to be lost (see the Comments on holotype of Coelorinchus hige ).

Among the FAKU collection was a single specimen of N. proxima collected from off Minamidaito-jima Island (FAKU 13366, 1 spec., 59.4 mm HL, 366+ mm TL), but the register indicates its locality with a question mark. This record was not included in the distribution of this species (Appendix 3-10C). Amaoka et al. (2020) recently listed the species from Hokkaido, but it is obviously based on Sawada’s (1983) record from the Pacific off Tohoku.

Relationships and comparisons. Nezumia proxima is putatively most similar to N. namatahi McCann & McKnight, 1980 , a species known only from New Zealand and Australia, and they share the combination of 8–10 pelvic-fin rays (9–10 in N. namatahi ), a broad naked area on the underside of the snout, a long barbel (15–21% HL in N. proxima , and 13–30% in N. namatahi ), body scales covered with lanceolate to shield-shaped spinules in parallel to convergent rows, and a broad, prominent, dark band completely encircling the trunk. However, N. proxima readily differs from that species in that the anterior dermal window of the light organ (ADW) is situated between the inner pelvic-fin bases (vs. ADW usually distinctly posterior to a line connecting inner pelvic-fin bases). It further differs from N. namatahi in its tiny pores along the infraorbital and mandibular canals (vs. large and prominent). [Data for N. namatahi are based on Iwamoto & Williams (1999:194–195), Iwamoto & Graham (2001:489), and this study.]

Uncertain variant. A specimen collected from the Shichito-Iojima Ridge at a depth of 860–870 m ( Fig. 170 ; Table 12 ) was initially regarded as a different species from N. proxima by having a wider interorbital space (25% HL vs. 19–24%). It further differs from the typical N. proxima specimens examined in having a wider internasal space (24% HL vs. 19–23%), a larger posterior nostril (9% HL vs. 2–6%), a relatively shorter barbel (15% HL vs. 15– 21%), and slightly more scales below the second dorsal-fin origin (8.5 vs. 6–8). However, no significant differences were evident in squamation, spinulation of body scales ( Fig. 169 ), and the number and arrangement of cephalic sensory pores. Although the above differences may warrant their specific separation, the paucity of materials from the Shichito-Iojima Ridge did not allow a definitive conclusion. Therefore, the specimen was tentatively identified as an uncertain variant of N. proxima .

Figures

FIGURE 168. Fresh specimens of Nezumia proxima. (A) BSKU 45547, 43.8 mm HL, 264+ mm TL, east of Katsuura, Chiba Pref., Pacific, 507–578 m depth; (B) BSKU 44837, 54.2 mm HL, 319+ mm TL, Tosa Bay, Kochi Pref., Pacific, 700–720 m depth; (C) KPM-NI 28856, 44.8 mm HL, 236+ mm TL, west-southwest of Shirahama, Wakayama Pref., Pacific, 532 m depth. Lateral views. [Photos: (A–B) BSKU; (C) H. Senou]

FIGURE 169. Scanning electron micrographs showing body scales (from the dorsum below the interdorsal space) of Nezumia proxima. (A–B) BSKU 19764, typical specimen, 57.9 mm HL; (C–D) BSKU 19891, uncertain variant, 50.8 mm HL. (A, C) Views from above; (B, D) oblique views. [Photos: NSMT]

FIGURE 170. Uncertain variant of Nezumia proxima. BSKU 19891, 50.8 mm HL, 274+ mm TL, east-southeast of Miyake-jima Island, Shichito-Iojima Ridge, Pacific, 860–870 m depth. (A) Lateral view; (B) dorsal and (C) ventral views of head. Preserved condition. [Photos: N. Nakayama]