Heleopera lucida (Penard, 1890) Porfirio-Sousa et al., 2023
Basionym: Difflugia lucida Penard, 1890

Diagnosis: Shell hyaline, more or less U-shaped and strongly compressed, covered with flat quartz particles. Living individuals accumulate mainly inorganic material round the elliptic aperture. This aggregation of particles is probably drawn into the shell when the amoebae encysts and is lost when the cell dies. Nucleus ovular, about 10 µm in diameter, with a number of irregularly shaped nucleoli. Pseudopodia relatively thin.

Dimensions: Penard (1902): 50-60 µm, up to 65 µm. Todorov and Bankov (2019): Length 65-83 µm, width 33-56 µm, apertural width 20-41 µm.

Habitat: Freshwater, soil and mosses. A common species, cosmopolitan.

Heleopera lucida, , dry moss, the Netherlands

Heleopera lucida, 68 µm, Crailoo, the Netherlands and, H. lucida, 70 µm, Tirol, Austria

Heleopera lucida, right: lateral view, 70 µm – Tirol, Austria, and aperture of the specimen to the left.

The same shell as above; note the darker grains around the pseudostome.

Heleopera lucida, both c. 60 µm, xerophyll moss, Germany

Drawing: Penard (1902) in Faune Rhizopodique du Bassin du Leman

Stacked image partly showing the covering with flat xenosomes

Two living cells of Heleopera lucida – Photomicrography Angie Opitz, Austria.