Family Tyrrheniellidae Riedl, 1959
With pre-oral compact ovoid brain with paired lappets before, over and under it. Without protonephridia. Hermaphroditic gonad unpaired, ventral, male region anterior, duct passes below brain, large sperm cavity opens to antero-dorsal male pore, sperm elongate. Marine.
Type and only genus
Tyrrheniella Riedl, 1959
This animal was described by Riedl (1959) from only 2 specimens. He placed it in the Catenulida, but this has been questioned. As described it appears closer to the Acoela than the Catenulida, perhaps near the family Antigonariidae.