Choanocystidae Cavalier-Smith and von der Heyden 2007
Periplast with two contrasting types of siliceous scales, oval or bilobed tangential basal plate scales (margin not hollow and inrolled) and outer bipartite radial 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.
1. Choanocystis Penard 1904
Periplast with two types of endogenous silicious elements: tangential base plates and radial spicules. The base of the spicules is formed like a water lily. Funnel-shaped scales absent.
Choanocystis aculeata (Herwig & Lesser 1874), emend. Siemensma & Roijackers 1998