It is found off Japan and New Zealand, and possibly also South Africa and Australia, typically deeper than 300 m (980 ft).

This species can be distinguished from other lanternsharks by its coloration, which is a uniform dark gray or brown without the ventral surface being much darker and clearly delineated from the rest of the body.

An unusually high proportion of individuals in Suruga Bay are hermaphrodites, with both male and female characteristics.

The brown lanternshark was first described by Robert Engelhardt as Spinax unicolor in 1912, in the scientific journal Zoologischer Anzeiger.

[5] Confirmed specimens of the brown lanternshark have been captured from off southern Honshu, Japan, and around New Zealand.

The coloration is a plain dark gray or brown, slightly darker below and lighter on the dorsal fin margins.

[7] The most important prey of the brown lanternshark are bony fishes (mainly lanternfishes), followed by cephalopods (mainly the squid Watasenia scintillans), and finally crustaceans (mainly prawns such as Acanthephyra).

A study of brown lanternsharks in Suruga Bay by Yano and Tanaka (1989) found a 23% prevalence of hermaphroditism within the population.