Cyclopyxis quadratus var. grandis Balik, 1995

Diagnosis. Shell by ventral view tetragonal (square, oblong or trapezium) with rounded edges. By side view shell vaulted, almost hemispherical. The organic matter of shell covered with large, flat, polygonal mineral particles. The shell translucent, light brown-gray or light rusty brown. The aperture round or breath oval with undulated rim, uninvaginated, in the center of the bottom side of the shell. From the nominate form Cyclopyxis quadratus differs with its large dimensions only. Protoplasm. Not observed, only empty shells or encysted individuals were observed. In encysted individuals there is only one dark brown globular cyst, with smooth surface in the shell.

Dimensions: According to Balik (1995): Shell 148—158 × 146—157 μm, height 70—76 μm, diameter of aperture 62—69 μm.

Ecology. Primary mountain rain forest, very disintegrated leaf litter.

Geographical distribution: Vietnam, Tam-Dao. Cyclopyxis quadratus (nominate form) was found in the leaf litter of the vine and “arbre de Judée” in the neigbourhood of the Var city in France. A new variety was determined in very disintegrated leaf litter from a tropical rain forest. It is clear, that the nominate form and new variety are fixed on the disintegrated leaf litter.