Original descriptions of taxa. For coccolithophores, and many calcispheres, these are pages from the Catalog of Calcareous Nannofossils. In other cases (e.g. non-calcifying haptophytes) the data is directly compiled on this site. The "Catalogue of Calcareous Nannofossils" was compiled by Prof A. Farinacci 1969-1989 and updated by Richard Howe 2000-2016 - see also this page.
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Current identification/main database link: Prymnesium parvum Carter 1937; emend. Green et al. 1982Compiled data
Swimming cells 6-12 µm long x 3.5-8-0 µm broad; mostly sub-spherical to elongate with more or less parallel sides and rounded posterior end; sometimes bent or pyriform or with a tapered posterior end; anterior end obliquely truncate. Two equal or sub-equal distally tapered heterodynamic flagella, 10-14.5 µm in length and a short, 3.0-5.0 µm, flexible non- coiling haptonema arising sub-apically from a groove or depression in the truncate face. Swimming motion smooth, the cell rotating about its longitudinal axis and the anterior (flagellar) pole describing a helix about the path of travel; flagella directed posteriorly.
Body scales 0.36-0.37 µm x 0.25-0.27 µm, of two types in two layers: scales of the inner layer with a narrow inflexed rim, a central thickening on the distal face, and a radial fibrillar pattern on both faces; scales of the outer layer similar but with relatively tall upright rims.
Chloroplasts two, lateral and parietal, yellow-green to olive, lobed or dissected, each with an immersed pyrenoid. Nucleus central between the chloroplasts, Golgi body parabasal. Reserve metabolite probably chrysolaminarin (leucosin) accumulated in a posterior vacuole. Peripheral muciferous bodies and usually several lipoidol globules present.
Cysts ovoid, 9.3-10.8 µm x 6.0-6.4 µm, with a simple sub-anterior pore, the latter 2.75- 3.00 µm in diameter; wall composed of layers of scales with electron-dense siliceous material deposited on the distal surfaces of the outermost scales.