Palombiellinae with a spermiduct. Oviducts not directly communicating with the lateral bursae. Testes ventral, dorsal, or dorso-ventral.
This genus contains the following species: Synsiphonium liouvilli Hallez, 1911, S. ernesti (Hyman, 1958), S. angustus Sluys and Ball, 1989.