Spicomacrurus kuronumai ( Kamohara, 1938 )

Schwarzhans, Werner, 2014, Head and otolith morphology of the genera Hymenocephalus, Hymenogadus and Spicomacrurus (Macrouridae), with the description of three new species, Zootaxa 3888 (1), pp. 1-73 : 21-22

Spicomacrurus kuronumai ( Kamohara, 1938)

Figs. 3E–F , 4E–G , 5

Hymenocephalus kuronumai Kamohara, 1938: 70 (type locality: Tosa Bay).

Hymenogadus (Spicomacrurus) kuronumai: Okamura, 1970: 64 .

Spicomacrurus kuronumai: Iwamoto, Shao & Ho, 2011: 515 .

Material examined. 2 specimens; 1 specimen NSMT 46796, 164 mm TL, 34°57’N, 138°43’E, 315–500m ; 1 specimen NSMT 103488, 157 mm TL, 31°29–32’N, 128°30–31’E, 550– 596 m .

Diagnosis. Pelvic fin rays 8; nasal bones closely adjoining along mesial edges, forming three horizontal plate like processes; OL:OH = 1.45–1.6.

Comparison. For distinction from S. adelscotti see above. Spicomacrurus kuronumai also resembles S. mccoskeri , from which it differs in the number of pelvic fin rays (8 vs 9), the robust head shape (head length: height = 1.7 vs 2.3) and the more compressed otolith (OL:OH = 1.45–1.6 vs 1.95). Spicomacrurus kuronumai shows scale pockets on the occiput, a character otherwise only shared with S. dictyogadus .

Description. Head morphology ( Figs. 3E–F ): Head length to height about 1.7 with relatively firm head bones and platy spatulate nasal bones closely adjoining along mesial edges. Scales or scale pockets present on occiput in small patches behind nasal bones and in front of nape and in a row covering the skin over the supraorbital canal. Snout length 20% HL, orbit diameter 30–33% HL, interorbital width 35% HW. Barbel 15% HL, reaching vertical through center of orbit. Infraorbital, supraorbital and preopercular canal systems narrow with widths <10% HL, covered by rather thick, firm skin. Few small pores visible in skin of infraorbital and in posterior mandibular positions. Preopercular angle broad, not projecting.

Otolith morphology ( Figs. 4E–G ): Thin and moderately elongate otoliths with slightly convex inner and flat outer face. OL:OH = 1.45–1.6; OH:OT = 6. Predorsal lobe low, rather indistinct; ventral rim similarly deep; anterior tip blunt, posterior tip rounded. Rims often somewhat ornamented; postdorsal section deeply indented in one specimen ( Fig. 4G ). Sulcus slightly supramedian with narrow, ventrally indented collum. Colliculi large, reaching close to anterior and posterior rims of otolith, caudal colliculum only slightly longer than ostial colliculum ( CCL: OCL = 1.0–1.2); pseudocolliculum indistinct, short; TCL: PCL = 7–8. Dorsal depression large; ventral furrow distinct, turning upwards and away from ventral rim posteriorly .

Distribution. ( Fig. 5 ) Off southeastern Japan ( Okamura, 1970) to northern Taiwan ( Iwamoto et al., 2011).

Figures

FIGURE 3. Heads of the species of Spicomacrurus: A–B—Spicomacrurus dictyogadus, holotype, MNHN 2009-1455, redrawn from Iwamoto, Shao & Ho (2011), A—Lateral view, B—Dorsal view. C–D—Spicomacrurus adelscotti, WAM P.28073-004, C—Lateral view, D—Dorsal view. E–F—Spicomacrurus kuronumai, E—Lateral view, NSMT P46796, F—Dorsal view, NSMT P103488. G–H—Spicomacrurus mccoskeri, MNHN 1994-0881, G—Lateral view, H—Dorsal view.

FIGURE 4. Otoliths of the species of Spicomacrurus: A–B—Spicomacrurus adelscotti, WAM P.28073-004, A—Inner face, B—Ventral view. C–D—Spicomacrurus mccoskeri, MNHN 1994-0881, C—Inner face, D—Ventral view. E–G—Spicomacrurus kuronumai, E–F—NSMT P46796, E—Inner face, F—Ventral view, G—NSMT P103488, inner face.

FIGURE 5. Geographical distribution of the species of Spicomacrurus.