then divides until only uninucleate cells remain. The cyst wall is thickly layered 7–8 times and includes gelatinous layers, layers of silica plates, and iron. Taxonomy Originally placed in Heliozoa (Sarcodina), the actinophryids are now understood to be part of the stramenopiles. They are unrelated to centrohelid and desmothoracid heliozoa with which they had been previously classified. There are several genera included within this classification. Actinophrys are smaller and have a single, central nucleus. Most have a cell body 40–50 micrometer in diameter with axopods around 100 μm in length, though this varies significantly. Actinosphaerium are several times larger, from 200 to 1000 μm in diameter, with many nuclei and are found exclusively in fresh water. A third genus, Camptonema, has a debated status. It has been observed once and was treated as a junior subjective synonym of Actinosphaerium by Mikrjukov & Patterson in 2001, but as a valid genus by Cavalier-Smith & Scoble (2013). Heliorapha is a further debated taxon, it being a new generic vehicle for the species azurina that was initially assigned to the genus Ciliophrys. Classification Order Actinophryida Hartmann 1913 [Actinophrydia Kühn 1926; Actinophrydea Hartmann 1913] Family Actinophryidae Dujardin 1841 Genus Actinosphaerium Ritter von Stein 1857 [Echinosphaerium Hovasse 1965] Species Actinosphaerium eichhornii (Ehrenberg, 1840) Stein, 1857 Species Actinosphaerium nucleofilum Barrett, 1958 Species Actinosphaerium akamae (Shigenaka, Watanabe etSuzaki, 1980) Mikrjukov & Patterson, 2001 Genus Actinophrys Ehrenberg 1830 [Trichoda Müller 1773 nomen oblitum; Peritricha Bory de St.Vincent 1824 nomen dubium non Stein 1859] Species Actinophrys sol (Müller, 1773) Ehrenberg, 1840 Species Actinophrys pontica Valkanov, 1940 Species Actinophrys salsuginosa Patterson, 2001 Species Actinophrys tauryanini (Mikrjukov, 1996) Mikrjukov & Patterson, 2001 Gallery References Amoeboids Actinochrysophyceae