Dana, 1852
Diagnosis
Integument thin and often very soft. Carapace moderately compressed; supra-orbital and hepatic spines present or absent, antennal, branchiostegal and pterygostomian spines always absent; cervical sulcus well marked, weak, or absent. Rostrum shorter than the eyestalk and often small or rudimentary.
Abdominal somites 1-5 dorsally rounded; somite 6 with weak carina. Telson with no more than three pairs, or without lateral movable spines.
Male ventral antennular flagellum modified into a clasping organ. Antennal flagellum consists of stiff proximal part and more flexible distal part. Mandibular palp three-segmented. Maxilliped 1 with exopod and epipod; maxilliped 2 with epipod only; maxilliped 3 and all pereiopods without exopod. Branchiae present. With some exceptions, pereiopods 1-3 or pereiopods 2-3 with minute chela. With some exceptions, pereiopods 4-5 reduced or absent. [Here, the description of petasma and thelycum is omitted].
Two species possible in the area: Sergia robusta and Sergestes arcticus.
[Diagnosis after Pérez Farfante and Kensley, 1997]