Species not formally described.
Cell body 4.3–5 µm diameter; flagella and haptonema not observed. Body scales of 4 types: a small number of long spine scales with an upwardly flexed rim, with the spine supported by 4 struts, overall length 10–20 µm; short spine scales with an upwardly flexed rim, distal surface of base-plate with c. 80 fine radiating striae, with the spine supported by 4 struts, overall length 0.3 µm; large elliptical plate scales 1 × 1.3 µm, distal surface with c. 80 fine radiating striae and a slightly thickened rim, proximal surface with a fibrous pattern; small elliptical plate scales, 0.5 × 0.7 µm, finely striated on one surface, patternless on the other.
Southern Ocean, south of Australia, 45.38–57.31°S 101.18–144.20°E.
Reported material closely resembles both C. vexillifera and our Chrysochromulina type C. Type A differs from C. vexillifera in having 4 types of scales (3 types in vexillifera), as well as some fine details of scale morphology. Type A differs from type C in the fine detail of scale morphology of the short spine scales. Until further material becomes available, we regard the 3 collections as representing different species, despite comparatively minor morphological differences.
Chrysochromulina genus description: Cells have homodynamic flagella and a coiling haptonema, and electron microscopy is usually required to identify the species. As well as being photosynthetic, these fragile haptophytes ingest picoplanktonic and nanoplanktonic organisms by phagocytosis.