Diagnosis
These are relatively (<1.5mm) small elongate species, that are normally epipelagic and often neritic. The carapace is unornamented and pellucid. They have a long undifferentiated frontal organ that projects beyond the end of the first antenna They are characterized by having around 20 setae on the pad on the fifth segment of the first antenna. Males have a hook appendage on the endopodite of the right second antenna only. Another distinguishing character is that the females are the only halocyprids that brood their eggs and early embryo stages in their carapace.
Remarks
There are seven known species of Euconchoecia (two with subspecies). These species are mostly neritic, epipelagic and tropical. One of the subspecies occurs in caves. Only one species, E. chierchiae, is oceanic and has been reported from the North Atlantic, but all records have been from south of 30N. Any female specimen brooding eggs or embryos within its carapace, is either a myodocopid species or, if it is a halocyprid, will be a Euconchoecia species.