The distribution of the species is holarctic; it can be found in North America, wide parts of Europe, and Asia.

[7] In 1837, William Kirby established the name Adoxus (derived from the Greek for "inglorious") as a subgenus of Eumolpus, with the species Cryptocephalus vitis as the type.

An application to conserve Bromius and other names by suppressing Eumolpus Illiger, 1798 was accepted by the International Commission on Zoological Nomenclature in 2012.

[9][10] Bromius obscurus adults are generally colored black, covered with dull yellow-grey hairs.

[12] A stridulatory apparatus has been observed on the upper sides of the wings of B. obscurus, the first known in representatives of the subfamily Eumolpinae.

It takes a form of a darkened convex microstructure spot near the end of each wing, between the RS and Cu veins.

Molecular phylogenetic analysis has showed that the bacterial symbiont of B. obscurus belongs to a distinct lineage of the Gammaproteobacteria.