Boreomysis sibogae

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Boreomysis sibogae is a small deep-sea crustacean, a mysid shrimp, in the Mysidae family and the Boreomysinae subfamily. It is mainly found in the Indo-Pacific, from the Northwest Pacific to the Southern Ocean, with some doubtful records from the Atlantic.

Habitat and biology
Boreomysis sibogae is an epi-bathypelagic species, meaning it lives in the deep parts of the ocean. Most records come from depths well below 1000 meters, but it has occasionally been found shallower, in the 50–200 meter range. Adults are about 13–38 mm long.

Appearance
- The carapace has a short, pointed rostrum and smoothly rounded sides.
- The telson (tail segment) is long and not dilated, with up to about 60 spine-like setae along the sides and 3 apical spines. The telson cleft is about one-fifth of its length.
- The eyes are slightly flattened and carry a papilla (a small projection); the eyes are not dominating the head.
- The antennal scale is broad and does not extend beyond the outer spine (in adults; in juveniles it can be a bit longer).
- Other body parts, like the uropods, have a couple of spines in typical fashion for the group.

Taxonomy and history
The species was first described from specimens collected during the Siboga expedition near Indonesia. A later name, Boreomysis spinifera, came from the Gulf of Aden, but it is now considered the same species. The classification has been complex because the original material was immature and poorly preserved, but today it is placed in the subgenus Boreomysis sensu stricto.

Type material and records
The original specimens used to name the species (syntypes) are housed at the Naturalis Biodiversity Center in Leiden. Boreomysis sibogae has been recorded across much of the Indo-Pacific, with some reports from the Northwest Indian Ocean and even the Atlantic debated. The type material was once noted as being infested by a tiny isopod borer, Streptodajus equilibrans.