Argynnia hesperia  Wailes, 1913 *)
Basionym: Argynnia dentistoma var. hesperia  Wailes, 1913

Diagnosis: This variety is distinguished from the A. lacustris Wailes, by the absence of any definite neck and by the structure of the test, which consists of small plates with regular outlines. Proportions of the test vary considerably, the width ranging from 0.6-0.8 of the length, the narrow tests having an ovoid outline. The average of 13 tests gave: length 175 µm, width 128 µm, aperture 38 µm; two tests each 170 µm in length measured 100 and 140 µm in width respectively.

Dimensions: According to Wailes (1913): Shell length 155—190 um; width 100—142 um; aperture 32—50 um, thickness 0.5—0.6 of the width.

Ecology: Sphagnum.

Geographical distribution: South-America (Puntas Arenas, Mt. Corovada, Rio de Janeiro).

Taxonomic note: *) Under ICZN Art. 45.6.4, infrasubspecific names (such as “var.”) published before 1961 are treated as available species‑group names, unless the author explicitly indicated infrasubspecific intent. Therefore, Argynnia dentistoma var. lacustris Wailes, 1912 is already an available species‑group name.