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

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