[1][2] First two specimens of B. inopinata were collected off Tasmania in the Huon Commonwealth Marine Reserve at the depth of 1060 m in 2015 during the research cruise of RV Investigator.

Another juvenile was pulled up onboard of the same vessel in 2017 from the greater depth of 2324–2634 m in the Central Eastern Commonwealth Marine Reserve off New South Wales.

[2] The species was discovered to have an uncommon for mysids additional armature on the antennal scale outer spine.

Its characteristic anterior margin of the carapace has a pointed rostrum with somewhat emerging smoothly rounded lateral angles.

Narrow antennal scale (4.7–5.5 times as long as wide) is uniquely armed in this species, with outer spine bearing additional one to four spinules.

The former species is also recorded in the Tasman Sea, and the initial genetic analysis seems to support the affinity to it.