Genus: Ovoid, firm; dorsal side convex, ventral side flattened; dorsal surface ridged; adoral zone reduced or rudimentary; macronucleus U-shaped or in two rounded parts (Kudo, 1966). Species: Ovoid, 50 μm long; dorsal surface with four ribs, the second from left of which carries a sharp backwardly curving thorn; 7 frontoventral, 5-6 transverse cirri; macronucleus horseshoe-shaped (Carey, 1992).

50 μm 100 μm 150 μm; x 400