Hymenocephalus papyraceus, : Okamura, 1970

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 : 37-38

Hymenocephalus papyraceus Jordan & Gilbert, 1904

Figs. 14F–J , 16

Hymenocephalus papyraceus Jordan & Gilbert, 1904: 614 (type locality: Sagami Bay , Japan).

Hymenocephalus papyraceus: Okamura, 1970: 56 .

Material examined. 12 specimens; 6 specimens BSKU 44292-44297 , 120 + –132+ mm TL, central Tosa Bay off Kochi, 600 m ; 1 specimen BSKU 44761, 170 mm TL, central Tosa Bay off Kochi, 600 m ; 1 specimen BSKU 99483, 171 mm TL, off southern Japan (no further data) ; 1 specimen BSKU 101959 , R / V Hakuro-maru (KH 73-2, St. 4); BSKU NMIC-ZF-03092 , 147 mm TL, off southern Japan (no further data) ; 1 specimen USNM 50935 (holotype), 112 mm TL, Sagami Bay , 220–485 m ; 1 specimen ZMMGU P-18258, 30°30’N, 129°19’E .

Diagnosis. Pelvic fin rays 10–11; pectoral fin rays 16–18; snout projecting, with thin, pointed tip, 20–25% HL; barbel short, 4–5% HL, not reaching vertical through anterior margin of orbit; orbit diameter moderate, 25–30% HL; interorbital width 70–80% HW; infraorbital width 16–20% HL; preopercular supporter very long, straight, 10–11% HL; gill rakers 18–22; ventral striae reaching to about ⅓ distance from pelvic fin bases to periproct; otolith with moderately high predorsal lobe, colliculi separated, closely placed across narrow collum, terminating far from anterior and posterior rims of otolith; OL:OH = 1.05; TCL:PCL = 2.1.

Comparison. Hymenocephalus papyraceus resembles H. aterrimus and H. neasaeae . From H. aterrimus it differs in the number of pelvic and pectoral fin rays (10–11 vs 13–14 and 16–18 vs 13–16, respectively), the smaller preopercular canal width (14–17 vs 19–23% HL), the smaller postorbital-preopercular interspace (4–6 vs 10–14% HL), the long and slender preopercular supporter (11 vs 3–4% HL) and the otolith with a distinct predorsal lobe. For difference with H. nesaeae see above.

Description. Head morphology (n = 3) ( Fig. 14F–H ): Head large, snout projecting, long, with thin pointed tip, which is easily damaged, snout length 20–25% HL, orbit diameter 25–30% HL, interorbital width 70–80% HW. Barbel short, 4–5% HL, not reaching vertical through anterior margin of orbit. Head canals well developed, large, infraorbital width 16–20% HL, supraorbital canal with 4 segments, width 17–20% HL, supratemporal canal rather distinct and wide, above segment 3 of supraorbital canal, preopercular canal width 14–17% HL, postorbitalpreopercular interspace 4–6% HL. Infranasal supporter small; infraorbital supporter short, expanding only beyond rear part of orbit, 40–60% OD; preopercular supporter very long, thin and straight (11% HL).

Otolith morphology (n = 1) ( Fig. 14I–J ): Otolith moderate in size, ventrally well rounded, dorsally with a distinct predorsal lobe, postdorsally somewhat undulating and regularly inclined towards rounded posterior tip; OL:OH = 1.05; OH:OT = 3.5. Inner face slightly convex, with median sulcus. Ostial and caudal colliculi small, narrowly placed across collum, terminating at considerable distance from anterior and posterior tips of otolith; pseudocolliculum moderately short. CCL:OCL = 0.85; TCL:PCL = 2.1. Dorsal depression small; ventral furrow distinct, moderately close to ventral rim, anteriorly and posteriorly turning away and upwards.

Distribution ( Fig. 16 ). Hymenocephalus papyraceus is only known off the southeastern coast of Japan, chiefly the Sagami and Tosa Bays and off Kagoshima.

Figures

FIGURE 14. A–B: Hymenocephalus barbatulus: A—Figure from Gilbert & Hubbs (1920). B—Figure from Cohen et al. (1990). C–E: Hymenocephalus nesaeae: Holotype, MNHN 1995-0869, C—Lateral view of head, D—Dorsal view of head, E—inner face of otolith. F–J: Hymenocephalus papyraceus: F—BSKU 099483, lateral view of head, G—Holotype, USNM 50935, lateral view of head, H—BSKU 099483, dorsal view of head, I—BSKU 44761, inner face of otolith, J—BSKU 44761, ventral view of otolith.

FIGURE 16. Geographical distribution of Hymenocephalus aterrimus, H. barbatulus, H. nesaeae, H. papyraceus and H. sazonovi.