''Hymenocephalus lethonemus'' is a species of

rattail Grenadiers or rattails are generally large, brown to black gadiform marine fish of the subfamily Macrourinae, the largest subfamily of the family Macrouridae. Found at great depths from the Arctic to Antarctic, members of this subfamily are am ...

. It occurs at depths of up to 485 m (1591 ft) in the waters off southern

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

, the Philippines and northern Taiwan. This is a small, slender rattail with a total length of up to 14 cm (5.1 in). It has a fairly long, sharp snout, small eyes, a large mouth and no chin barbel. There is a long

bioluminescent Bioluminescence is the production and emission of light by living organisms. It is a form of chemiluminescence. Bioluminescence occurs widely in marine vertebrates and invertebrates, as well as in some Fungus, fungi, microorganisms including ...

organ with two external lenses just in front of the

anus The anus (Latin, 'ring' or 'circle') is an opening at the opposite end of an animal's digestive tract from the mouth. Its function is to control the expulsion of feces, the residual semi-solid waste that remains after food digestion, which, d ...

References

Macrouridae Fish described in 1904 Fish of Japan Fish of the Philippines Fish of Taiwan Taxa named by David Starr Jordan Taxa named by Charles Henry Gilbert {{Gadiformes-stub