Sicyonia is a genus of prawns, placed in its own family, Sicyoniidae. It differs from other prawns in that the last three pairs of its pleopods are uniramous, rather than biramous as seen in all other prawns. Sicyonia contains 52 extant species, and one species known only from fossils from the Upper Cretaceous. Analyses using molecular phylogenetics suggest that the family Sicyoniidae is nested within the larger family Penaeidae, and that the latter family may need to be divided up, elevating each of its traditionally recognised tribes to the rank of family. The extant species are: