Greeff (1875: 1, figs 15, 16)
Gaarder et al. (1976: 346, pl. 71–76), Thomsen (1978b: 361, figs 4, 14), Takahashi (1981a: 12, pl. 7, figs 27, 28), Siemensma (1991: 273, fig. 64a–d)
Potamodiscus kalbei Gerloff (1968: 353)
Cell body spherical, to 50 µm diameter. Overlapping body scales circular to slightly elliptical, 5.88–5.90 × 4.8–5.2 µm, with 10 or 11 large perforations arranged in concentric hexagonal rings, 0.7 µm diameter, and scattered internal struts seen as black dots under TEM.
Prydz Bay, East Antarctica; Mawson Harbour, East Antarctica; Lützow-Holm Bay (Takahashi, 1981a); Denmark (Thomsen, 1978); Switzerland (Penard, 1904); Gulf of Mexico (Gaarder et al., 1976).
Thomsen (1978b) discussed important taxonomic aspects of this species, including Greeff’s (1873) short, original description and his subsequent, more detailed account (Greeff, 1875), as well as Penard’s (1904) emended description and the removal of P. fluviatilis from Radiolaria to Heliozoea. Recently collected Antarctic samples appear to have fewer perforations than those reported from localities in the Northern Hemisphere and summarised in Gaarder et al. (1976).