Hymenocephalus grimaldii Weber, 1913

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 : 63-64

Hymenocephalus grimaldii Weber, 1913

Figs. 34A–H , 37

Hymenocephalus grimaldii Weber, 1913: 169 (type locality: 07°19’S, 116°49’E).

Material examined. 18 specimens; 4 specimens BSKU 16709–16712 , Timor Sea ; 7 specimens BSKU 17010–17016 , 102 + – 148 mm TL, 12°42’S, 123°08’E ; 1 specimen BSKU 98160, 160 mm TL, 05°54’S, 119°29’E, 558–593 m ; 5 specimens BSKU 98162-63 , 98167 , 98169-70 , 05°54’S, 119°29’E, 558–593 m ; 1 specimen WAM P.32344-006, 117+ mm TL, 21°29’S, 113°58’E .

Diagnosis. Pelvic fin rays 8; pectoral fin rays 9–11, rarely 12; gill rakers 17–21. Barbel absent. Orbit moderately large, 34–38% HL, strongly oblique. Snout obtuse, short, barely protruding, 15–20% HL. Ventral striae extending to periproct. Preopercular supporter very long and narrow, 8–13% HL. Otolith very compressed with broad predorsal lobe, OL:OH = 0.75–0.8; colliculi fused; pseudocolliculum very long, TCL:PCL = 1.15–1.25.

Comparison. Hymenocephalus grimaldii is readily recognized by the combination of low counts of pelvic and pectoral fin rays, absence of a barbel, strongly obliquely oriented orbit and very long and narrow preopercular supporter. The otolith morphology adds another set of easily recognizable characters such as the broad, but rather shallow predorsal lobe, the very compressed otolith with the longest pseudocolliculum observed in all Hymenocephalus species (TCL-PCL = 1.15–1.25).

Description. Head morphology (n = 2) ( Fig. 34A–C ): Snout short, blunt, high, only slightly projecting, 15–20% HL, orbit diameter large, 34–38% HL, oriented at an angle of 70–80° inclination to long axis of fish, with the longest orbit diameter being 42–45% HL, interorbital width about 80% HW indicating the most advanced lateralization of the eyes. Barbel absent. Head canals well developed, infraorbital width 15–17% HL, supraorbital canal with 4 segments, width 15–18% HL, supratemporal canal above segment 3 of supraorbital canal, preopercular canal width 13–19% HL, postorbital-preopercular interspace 3–5% HL. Infranasal supporter small, thin; infraorbital supporter variable, extended below almost entire length of orbit (70–80% OD) in specimens from Indonesia ( Fig. 34A ), but below the rear part of the orbit only in the specimen off NW Australia (30–40% OD) ( Fig. 34B–C ); preopercular supporter very long and narrow, 8–13% HL, with straight rear margin.

Otolith morphology (n = 8) ( Fig. 34D–H ): Otolith large; OL:OH = 0.75–0.8; OH:OT = 3.2–3.5. Dorsal rim with moderately large but very broad, mostly smooth predorsal lobe, distally reaching close to the obtuse, broadly rounded posterior tip without indentation mark; ventral rim very deep, regularly curved, smooth, deepest anterior of the middle; anterior rim high, nearly vertical. Inner face slightly convex, with slightly supramedian sulcus. Colliculi completely fused, terminating far from anterior and posterior tips of otolith, sometimes dorsally reduced and then rather narrow; pseudocolliculum very long. TCL:PCL = 1.15–1.25. Dorsal depression indistinct; no ventral furrow, instead broad, indistinct depression at center of ventral field and parallel to ventral rim of otolith.

Distribution. ( Fig. 37 ) Hymenocephalus grimaldii has been collected in the Timor and Java Seas of Indonesia, and one specimen has now been identified from off Northwest Cape, Western Australia.

Figures

FIGURE 34. Hymenocephalus grimaldii: A—WAM P.32344-006, lateral view of head, B–C—BSKU 098160, B—Lateral view of head, C—Dorsal view of head. D–H—Otoliths, D—Anterior view, E—Ventral view, F–H—Inner faces, D–E—WAM P.32344-006, F—BSKU 17010, G—BSKU 17011.

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