Genus: Cell body naked (without cell wall or lorica); oval or elliptical; dicentrically symmetrical; 2 equal-length flagella; chloroplast bowl-shaped or parietal plate, often colored red or orange owing to excess carotenoid pigments; stigma present in most species; 2 anterior contractile vacuoles; fresh water (Illustrated Guide, 1985). Species:

50 μm 100 μm 150 μm; x 400

Diatoma sp. (? or Fragilaria or ... ?), attached by Dunaliella sp., x 400, by Y. Tsukii
50 μm 100 μm 150 μm; x 400

cf.
D. salina (Dunal) Teodoresco: 16-24 μm long, 10-13 μm wide; broadly ovoid, ellipsoidal or cylindrical; central region sometimes constricted; bowl-shaped chloroplas (Illustrated Guide, 1985).