Norway to Mediterranean. It has been suggested that the Holoturian Neopentadactyla mixta (Östergen, 1848) was the host of this species in Atlantic (Cabioch & al., 1978), while this could be Pseudothynoe raphanus (Duben & Koren, 1845) in Mediterranean (Scuderi & Criscione, 2011). Hence, the species occurs in the infralittoral and circalittoral levels.