Alekperov and Mamaeva, 1992
Small to medium-sized phyllopharyngiids with ellipsoid to spherical body, no distinct dorsoventral differentiation. Cytostome apical, protruding slightly, with conspicuous oral basket. Somatic ciliation fairly complete, composed of longitudinal and few spiralling kineties. Several short adoral membranelles. No stylus.
Gymnozoum [= Kryoprorodon Alekperov and Mamaeva, 1992; Spiroprorodon Fenchel and Lee, 1972] was previously included in Enchelyidae or Prorodontidae (Alekperov and Mamaeva, 1992; Fenchel and Lee, 1972), which is inappropriate. Based on an ultrastructural study, Sniezek and Small (1993) proposed that it belongs in the subclass Phyllopharyngia de Puytorac et al., 1974. This is corroborated by morphological and morphogenetical investigations by Petz et al. (1995a,b), who proposed a close relationship to cyrtophorids. Species of this genus are very likely widespread in the marine plankton; some found in the Southern Ocean (Petz et al., 1995a).
Planctonic species recorded:
Holophrya pelagica