B.Leadbeater & Manton (Leadbeater & Manton, 1971: 67, figs 1–13)
Hallegraeff (1983: 496, fig. 5a–c), LeRoi & Hallegraeff (2004: 75, fig. 2)
Cells saddle-shaped, ventrally concave, dorsally convex, 6–10 µm long and wide, biflagellate. Body scales of 2 types: outer layer of short spine scales, with spine c. 0.5 µm long and attached to base-plate by 4 rigid arched supporting struts, the base-plate elliptical to circular, concave, 0.45–0.5 µm diameter, with distal surface patterned with delicate ±radiating striae; underlayer of flat oval plate scales c. 0.6 µm long, with a slightly thickened rim, patterned similar to spine scale base-plate. Flagella equal, c. 40 µm long, arising from concave ventral surface of cell c. one-third along cell length from posterior end. Haptonema c. 40 µm long when extended, coiled into 15–20 gyres when retracted.
Southern Ocean, south of Australia; Great Britain and Norway (Leadbeater & Manton, 1971).
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.