Hymenocephalus torvus Smith & Radcliffe, 1912

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 : 61-62

Hymenocephalus torvus Smith & Radcliffe, 1912

Figs. 33A–G , 37

Hymenocephalus torvus Smith & Radcliffe, 1912: 110 (type locality: off Jolo, 06°00’N, 120°45’E; location corrected by Jordan & Gilbert, 1920).

Hymenocephalus torvus: Iwamoto & McCosker, 2014: 281 .

Hymenocephalus striatissimus torvus : Jordan & Gilbert, 1920: 530.

Material examined. 15 specimens; 2 specimens (otoliths only) USNM 148995 , 13°47’N, 121°35’E, 347 m ; 5 specimens USNM 149032 , 96 + – 143 mm TL, Albatross Philippines Expedition (no further details) ; 1 specimen USNM 149465, 160 mm TL, 08°37’N, 124°36’E, 402 m ; 1 specimen USNM 149468, 162 mm TL, 08°35’N, 124°36’E, 366 m ; 1 specimen (otolith only) USNM 149471 , 13°32’N, 121°01’E, 446 m ; 2 specimens ZMUC unregistered 09.03.1914, 117– 136 mm TL, 07°25’N, 123°14’E .

Diagnosis. Pelvic fin rays 7 (rarely 8 on one side); pectoral fin rays 12–14; gill rakers 19–22. Barbel short, 10–15% HL. Orbit 34–40% HL. Snout short, only slightly protruding, 15–20% HL. Ventral striae extending to periproct. Infraorbital supporter long, 80–90% OD. Otolith compressed, OL:OH = 0.8–0.9; colliculi fused; pseudocolliculum long, TCL:PCL = 1.35–1.5.

Comparison. For differences see discussion to H. aeger and H. striatissimus .

Description. Head morphology (n = 2) ( Fig. 33A–B ): Snout short, slightly projecting, 15–20% HL, orbit diameter large, 34–40% HL, interorbital width 60–70% HW. Barbel short, 10–15% HL, not or just reaching vertical through anterior rim of orbit. Head canals well developed, infraorbital width 12–15% HL, supraorbital canal with 5 segments, width 13–15% HL, supratemporal canal above segment 4 of supraorbital canal, preopercular canal width 12–16% HL, postorbital-preopercular interspace 4–7% HL. Infranasal supporter moderately large; infraorbital supporter long, extended below almost entire length of orbit, 80–90% OD; preopercular supporter moderately long, 5–8% HL, with straight rear margin.

Otolith morphology (n = 10) ( Fig. 33D–G ). Otolith large; OL:OH = 0.8–0.9; OH:OT = 3.5. Dorsal rim with very large, broad, undulating or crenulated predorsal lobe, distally marked by indentation; posterior tip rounded, positioned at about level of sulcus termination; ventral rim deep, regularly curved, smooth, deepest anterior of the middle; anterior rim high, nearly vertical. Inner face slightly convex, with median sulcus. Colliculi completely fused, terminating far from anterior and posterior tips of otolith; pseudocolliculum very long. TCL:PCL = 1.4–1. 5. Dorsal depression moderately large, moderately indistinct; ventral furrow distinct, close to ventral rim.

Discussion. I follow Iwamoto and McCosker’s (2014) rationale in regarding H. torvus as a species separate from H. striatissimus , with snout profile and pectoral fin counts probably adding further characters for distinction, while otolith morphology does not.

Distribution ( Fig. 37 ). The geographic distribution of H. torvus appears to be restricted to the Philippines.

Figures

FIGURE 33. Hymenocephalus torvus: A–B—USNM 149465, A—Lateral view of head, B—Dorsal view of head. C–G—MNHN 2005-0928, otoliths, C, D, F—Inner faces, E—Anterior view, G—Ventral view.

FIGURE 37. Geographical distribution of Hymenocephalus aeger, H. megalops, H. striatissimus, H. torvus, H. grimaldii, H. neglectissimus, H. semipellucidus, H. sp. 1 and H.