centrohelid heliozoa Kühn, 1926 Suborder Pterocystina Cavalier-Smith & von der Heyden, 2007 1 Family Pterocystidae Cavalier-Smith & von der Heyden, 2007 2 Family Choanocystidae Cavalier-Smith & von der Heyden, 2007 3 Family Heterophryidae Poche, 1913