Choanocystidae Cavalier-Smith and von der Heyden, 2007
Diagnosis: Periplast with two contrasting types of siliceous scales, oval or bilobed tangential basal plate-scales (margin not hollow and inrolled) and outer bipartite radial spine-scales consisting of a vertical stalk, sometimes curved or branched but lacking lateral wings, emanating from near a strong indentation on one side of a flat horizontal basal disc. Funnel-shaped scales absent.
Type genus: Choanocystis Penard 1904