Anthosomidae. Male probably unknown. Female: Head fused with first thoracic segment, cephalothorax usually with lateral wing-like expansions; second and third thoracic segments fused but with separate dorsal plates, and with lateral expansions which extend slightly posterolaterally but do not fuse with plate of fourth segment; fourth segment covered by a dorsal plate which extends posteriorly to hide the posterior part of the body and all or most of the egg strings in dorsal view; genital segment small, abdomen small and rounded; caudal laminae small, irregular in outline with a lateral spine-bearing projection and further spines posteriorly; eggs uniserriate, flattened; egg strings long, coiled between third pereiopods and plate of fourth thoracic segment; first antenna with six or seven segments, several with short setae; second antenna subchelate; mandibular palp with two rami, at least one with spines; maxilla of two segments usually with rows of spines distally; maxilliped subchelate; first four pereiopods biramous; first pereiopods with rudimentary one-segmented rami; second pereiopods held at right angles to body, rami fused with basipod; third pereiopods large, thickened lamellae with endopod covering egg strings in ventral view and exopod hiding them in lateral view; fourth pereiopods lamellar, divided nearly to base, about half length of third pereiopods, which completely hide them in ventral view; fifth pereiopods uniramous, rudimentary.

Parasites on marine teleosts.

Type species: Aethon quadratus Krøyer, 1836.