Planinosphaeridium choane (Reid, 1974) Wall et al., 1977

Now Ataxiodinium. Originally (and now) Ataxiodinium, subsequently Planinosphaeridium.
Tax. jr. synonym of Planinosphaeridium membranaceum Eisenack, 1965, according to Dale, 1976; however, Edwards and Andrle, 1992 retained Ataxiodinium choane as a separate species.
Holotype: Reid, 1974, pl.1, figs.12
Age: Recent

Original description: Reid 1974. p. 588-589
Diagnosis: Inner capsule circular to subcircular and single walled, covered by an outer expanded crenulate membrane attached around the archeopyle and by fullel shaped depressions to the inner wall.
Dimensions: Holotype: inner capsule 30x30 µm, complete test 49x49 µm;
Range: inner capsule 28x26 to 40x37 µm, complete test 47x47 to 50x58 µm.
Description: The inner capsule is usually circular in outline, but may be slightly elongated in a polar direction. The outer microgranular membrane at times appears to form fields and a depression indicating the ventral sulcus. The wall of the inner capsule is thin 0.6 µm, single layered, yellow in colour and appears to have a smooth surface. A precingular archeopyle is thought to be present because of its similar shape to the archeopyles of other known precingular genera.