Hymenogadus Gilbert & Hubbs, 1920

Nakayama, Naohide, 2020, Grenadiers (Teleostei: Gadiformes: Macrouridae) of Japan and adjacent waters, a taxonomic monograph, Megataxa 3 (1), pp. 1-383 : 222-223

Genus Hymenogadus Gilbert & Hubbs, 1920

[Japanese name: Oni-sujidara-zoku]

Hymenogadus Gilbert & Hubbs, 1920:521 (as subgenus of Hymenocephalus ; type species: Hymenocephalus gracilis Gilbert & Hubbs, 1920 , by original designation).

Diagnosis. Anus immediately anterior to anal-fin origin, surrounded by narrow periproct. Ventral striae, consisting of fine, parallel black lines over silvery layer on each side of isthmus, shoulder girdle, most of chest, and posterior to pelvic fins. Gular region covered with fine striations of black epithelium. Light organ developed as long tube, extending from anus to slightly anterior to pelvicfin bases; small lens at each end of light organ. Second spinous ray of first dorsal fin serrated along its leading edge. Pelvic-fin rays 8, outer ray slender, not expanded or ribbon-like distally. Teeth all small, in narrow villiform bands in both jaws. Trunk shallow, cylindrical in cross section. Head bones thin, fragile; head skin membranous, translucent. Nasal bones weakly ossified, not forming stout, dorsoventrally flattened processes. Chin barbel present. Branchiostegal rays 7. Species small, less than 13 cm TL. Body with silvery reflection when fresh. [From Iwamoto et al. (2011), McMillan & Iwamoto (2014), and Schwarzhans (2014).]

Remarks. Hymenogadus was originally established as a subgenus of Hymenocephalus Giglioli, 1884 , with the type species H. gracilis ( Gilbert & Hubbs, 1920) . Subsequently, Okamura (1970a) elevated this taxon to full generic rank, with description of another subgenus Spicomacrurus . In addition to H. gracilis , Hymenogadus includes H. tenuis ( Gilbert & Hubbs, 1917) known only from the holotype collected from Hawaii.