Giard & Bonnier, 1889
Female with the pereion very short; ovary without external dorsal processes, but with two ventral processes, the posterior of which is long and often extends into the host pleon. Oostegites 2 to 5 boundaries difficult to distinguish in ripe female, forming a brood pouch enclosing ovarian lobes and oostegite 1. Oostegite 1 with anterior and unusually long posterior lamellae only; transverse lamellae absent. Colour violet or white. Male free in the pereion and pleon of the host, on the female abdomen, or in the female brood pouch. Length 1-3-5 mm.
Parasitic on the pea-crab Pinnotheres pisum , infecting the mussel Mytilus edulis .
Southern North Sea and south-west coasts of the British Isles.