Family Theonellidae Lendenfeld, 1903

Diagnosis (after Pisera and Lévi 2002; Fromont and Pisera, 2011): polymorphic, choanosomal spicules as tetraclone desmas; ectosomal spicules as phyllo- to discotriaenes; large choanosomal oxeas sometimes present; megascleres sometimes completely absent (some Theonella); microscleres characteristically as small, acanthose microrhabds, sometimes centrangulate or with slight curve, sometimes as streptasters and microrhabds ( Manihinea) or streptasters only ( Racodiscula).

Type-genus: Theonella Gray, 1868 .