Spicomacrurus kuronumai

Spicomacrurus kuronumai (Kamohara, 1938)

[Japanese name: Yari-dara]

(Figs. 191–192; Appendix 3-12A)

Hymenocephalus kuronumai Kamohara, 1938:70, fig. 40 (original description; holotype from Mimase fish market; new Japanese name: “Yari-dara”); Kamohara 1950:278 (listed; Kochi and Wakayama Pref.); Matsubara et al. 1951:42 (listed; Mie Pref.); Kamohara 1952:97, fig. 95 (description; 1 spec. from Mimase fish market); Matsubara 1955:1315 (in key; Japan); Kamohara 1958:73 (listed; Kochi Pref.); Okada et al. 1959:83 (listed; Kumano-nada); Kamohara 1961c:9, pl. VII, fig. 1 (invalid designation of neotype; BSKU 4333 from Mimase); Kamohara 1964:96 (listed; Kochi Pref.); Shinohara et al. 2001:305 (1 spec. listed from Tosa Bay); Shao et al. 2008b: table 2 (1 spec. listed from northeastern Taiwan; first Taiwanese record).

Hymenogadus kuronumai: Okamura 1970a:64, pl. III, text-fig. 28 (new combination; description; biological notes; 79 spec. from Pacific off southern Japan from Miya to Shibushi); Okamura 1970b: table 1 (listed; Japan); Kataoka & Tomida 1981:78 (listed; Mie Pref.); Tominaga & Uyeno 1981:489 (listed; Japan); Ozawa 1983:13 (listed; off Makurazaki, Kagoshima Pref., East China Sea); Okamura 1984a:203, 359, fig. 144 [brief description; 6 spec. from Okinawa Trough; photo based on BSKU 40016 (from off Kochi Pref.)]; Okamura 1984b:93, pl. 80, fig. I (compiled); Okamura 1988:93, pl. 80, fig. I (compiled); Nakabo 1993:354 (in key; Japan); Okamura 1997:128, fig. 5 (compiled); Shinohara & Matsuura 1997:292, pl. 2-C (listed; Suruga Bay); Suzuki & Kataoka 1997:81, pl. 32, fig. 174 (brief description; 1 spec. from off Owase); Nakabo 2000:418 (in key; Japan); Nakabo 2002:418 (in key; Japan); Yoda et al. 2002:11 (listed; East China and Yellow Seas); Nakajima 2003:52 (brief description; 1 spec. from Enshu-nada); Shinohara et al. 2005:418 (listed; Ryukyu Islands); Furuhashi et al. 2010: table 2 (20 spec. listed from northern Okinawa Trough).

Spicomacrurus kuronumai: Iwamoto et al. 2011:518 (in key; elevation of Spicomacrurus to full generic status); Nakabo & Kai 2013:494 (in key; Japan); Ikeda & Nakabo 2015:319, pl. 64, figs. 5–10 (brief description; spec. from Wakayama Pref.); Iwamoto et al. 2015:103 (brief description; 2 spec. from northeastern Taiwan); Motomura 2020:39 (listed; Japan).

Diagnosis. A species of Spicomacrurus with 8–9 (usually 8) pelvic-fin rays; nasal bones closely adjoined mesially, forming 3 broad horizontally flattened processes; trunk shallow, cylindrical in cross section, width over pectoralfin bases 0.9–1.3 in depth below first dorsal-fin origin; snout short, low, but distinctly protruding beyond upper jaw, length 27–31% HL; interorbital width 16–23% HL; upper-jaw length 37–41% HL; barbel short, but well developed, length 11–17% HL; pelvic-fin length 47– 69% HL, distal portion of outer pelvic-fin ray distinctly expanded; body scales large, transverse rows below midbase of first dorsal fin 2.5–3.5, below second dorsalfin origin 2–3; longitudinal scales over distance equal to predorsal length 17–22.

Material examined. 30 specimens. Japan: BSKU 4333 [invalid neotype of Hymenocephalus kuronumai designated by Kamohara (1961); 25.0 mm HL, 116+ mm TL], Mimase fish market, Kochi Pref., Japan, coll. T. Kamohara, 30 Nov. 1954; BSKU 109035 (1, 35.9 mm HL, 182+ mm TL), west of Sanpo-sone, 32.2872ºN, 129.0732ºE, 351–389 m, T/ V Nagasaki-maru, cr. N365, sta. B4, 3-m ORE beam trawl, coll. N. Nakayama, 19 Nov. 2012; BSKU 13356 (1, 36.6 mm HL, 166+ mm TL), BSKU 13358 (1, 39.1 mm HL, 177+ mm TL), BSKU 13360 (1, 29.7 mm HL, 132+ mm TL), BSKU 13363 (1, 35.7 mm HL, 195+ mm TL), BSKU 13366 (1, 33.2 mm HL, 167+ mm TL), BSKU 13369 (1, 36.1 mm HL, 180+ mm TL), BSKU 13373 (1, 32.7 mm HL, 161+ mm TL), BSKU 13375 (1, 35.8 mm HL, 169+ mm TL), BSKU 13376 (1, 37.0 mm HL, 183+ mm TL), BSKU 13377 (1, 37.8 mm HL, 159+ mm TL), BSKU 13378 (1, 29.6 mm HL, 139+ mm TL), BSKU 13379 (1, 33.5 mm HL, 157+ mm TL), BSKU 13380 (1, 34.4 mm HL, 175+ mm TL), BSKU 13381 (1, 40.2 mm HL, 201+ mm TL), BSKU 13383 (1, 40.0 mm HL, 193+ mm TL), BSKU 13385 (1, 37.5 mm HL, 155+ mm TL), BSKU 13387 (1, 22.8 mm HL, 117+ mm TL), BSKU 13389 (1, 35.3 mm HL, 170+ mm TL), west of Muroto, Tosa Bay, 360–435 m, coll. O. Okamura, 8 Jun. 1968; BSKU 12946 (1, 22.4 mm HL, 106+ mm TL), Tosa Bay, 350–450 m, bottom trawl, 14 May 1968; BSKU 4365 (1, 24.3 mm HL, 126+ mm TL), Mimase fish market, coll. T. Kamohara, 5 Dec. 1954; KSHS 297 (1, 23.2 mm HL, 120+ mm TL), KSHS 298 (1, 23.8 mm HL, 108+ mm TL), Mimase fish market, coll. T. Yamakawa, 4 Dec. 1960; BSKU 40016 (1, 33.9 mm HL, 156+ mm TL), off Okino-shima Island, Kochi, 250 m, bottom trawl, 18 Apr. 1984; BSKU 13117 (1, 26.8 mm HL, 149+ mm TL), BSKU 13235 (1, 34.1 mm HL, 166+ mm TL), BSKU 13259 (1, 34.6 mm HL, 162+ mm TL), BSKU 13260 (1, 33.8 mm HL, 157+ mm TL), BSKU 13261 (1, 33.5 mm HL, 173+ mm TL), east of Cape Ashizurimisaki, Tosa Bay, 420–555 m, coll. Y. Mishima (= Y. Machida), 2 Jun. 1968.

Counts and measurements. Based on 30 specimens (22.4–40.2 mm HL, 106+–201+ mm TL). Counts: first dorsal-fin rays II,10–12; pectoral-fin rays i17–i21; pelvic-fin rays 8–9; gill rakers on first arch (outer/inner) 6–10/11–15, on second arch 11–17/10–15; longitudinal scales 17–22; transverse scale rows below first dorsalfin origin 3–4.5, below first dorsal-fin midbase 2.5–3.5, below second dorsal-fin origin 2–3, above anal-fin origin 7.5–9.5.

The following measurements are in% of HL, followed by those in % of PRL in parentheses: snout length 27–31 (34–43); orbit diameter 27–37 (38–48); postorbital length 42–47 (54–65); postrostral length 72–78; orbit–preopercle distance 32–36 (43–50); suborbital width 8–11 (10–14); upper-jaw length 37–41 (49–56); length of rictus 33–37 (43–50); length of premaxillary tooth band 27–32 (35– 43); preoral length 16–19 (20–26); distance between tip and lateral angle of snout 18–21 (23–29); snout width 29– 35 (39–46); internasal width 17–20 (23–26); interorbital width 16–23 (21–31); occipital width 7–9 (9–13); body width over pectoral-fin bases 39–62 (52–84); body depth at first dorsal-fin origin 49–64 (65–88); body depth at analfin origin 42–55 (55–75); prepelvic length 93–106 (121– 145); preanal length 152–173 (198–234); isthmus–pelvic distance 44–50 (58–69); isthmus–anal distance 100–118 (130–159); pelvic–anal distance 56–72 (74–98); pelvicfin length 47–69 (63–95); pectoral-fin length 56–68 (76– 93); predorsal length 96–107 (127–146); height of first dorsal fin 63–79 (86–107); length of first dorsal-fin base 29–38 (40–52); interdorsal length 62–86 (82–119); length of gill slit 19–25 (25–34); length of posterior nostril 4–8 (5–11); barbel length 11–17 (15–23).

Size. To about 21 cm TL (FAKU 24937, 211+ mm TL, Owase, Japan).

Distribution. Restricted to Japan and Taiwan.Known from off the Pacific coasts of southern Japan northward to the Izu Peninsula (138.96ºE), northern Okinawa Trough, and northern Taiwan, at depths of 205‾ 680 m (Shao et al. 2008b; this study; Appendix 3-12A). Usually rare, but many individuals occasionally collected by bottom trawls.

Comments on type specimen. Spicomacrurus kuronumai was originally described as a new species of Hymenocephalus Giglioli, 1884 based on a single specimen collected from the Mimase fish market, Kochi, Japan. Unfortunately, the holotype was destroyed by a fire during WWII. In his list of type specimens deposited in BSKU, Kamohara (1961c) designated a neotype of this species (BSKU 4333, 25.0 mm HL, 116+ mm TL). However, his designation is considered to be invalid, according to Art. 75.2 of the ICZN (1999).

Remarks. For a full description see Okamura (1970a; as a species of Hymenogadus Gilbert & Hubbs, 1920). Although Iwamoto & Merrett (1997) reported S. kuronumai (as a species of Hymenocephalus) from the Coral Sea, their specimens currently comprise the type series of S. mccoskeri Iwamoto, Shao & Ho, 2011. Last et al. ’s (2014) record of S. kuronumai from the western Coral Sea also seems to be referred to as S. mccoskeri.

Comparisons. Among the other three congeners (see the Remarks of the genus), S. kuronumai is most similar to S. adelscotti Iwamoto & Merrett, 1997 known from Fiji (type locality) and Western Australia. The two species readily differ from C. dictyogadus Iwamoto, Shao & Ho, 2011 and S. mccoskeri in that the nasal bones are closely adjoined mesially (vs. broadly separated by the rostral cartilage), and by having a wider interorbital space (16–23% HL vs. 8–15%) and a smaller mouth (upper-jaw length 37–42% HL vs. 46–50%) [data for S. dictyogadus and S. mccoskeri are from Iwamoto et al. (2011)]. According to the key to species of Spicomacrurus given by Iwamoto et al. (2011:518), S. kuronuma i differs from S. adelscotti in having eight pelvic-fin rays (vs. nine), with its outer ray distinctly flattened and expanded distally (vs. only slightly flattened and expanded). However, the S. kuronumai specimens examined rarely had eight pelvicfin rays, and the outer ray was not flattened nor expanded distally, when its fleshy flange was completely missing (see Iwamoto et al. 2011: fig. 1B vs. 1D). Nevertheless, S. kuronumai readily differs from that species in its longer barbel (11–17% HL vs. 9%) and higher counts of outer gill rakers (those on the lower limb of the second arch 9–14 vs. 7). According to Schwarzhans (2014:20, fig. 4), the two species are also separable by otolith morphology: the otolith of S. kuronumai is not strongly depressed dorsoventrally, with its height being 1.45–1.6 in its longitudinal length (vs. 1.75).