Prymnesium Massart 1920

Coccolithophorids, cells sub-spherical to elongate, sometimes compressed, 2 two equal or sub-equal flagella and a flexible non-coiling haptonema, flagella 1 - 1.5 x cell length, haptonema approx. 1/3 to 1/5 the length of the flagella, flagella sometimes with a covering of scales, arising sub-apically from the obliquely truncate apical pole; one flagellum often held closely to the cell body, the other extended away from the cell; haptonema directed forwards during swimming, usually 2 chloroplasts with immersed or bulging pyrenoids; eyespot absent, contractile vacuole sometimes present anteriorly; muciferous bodies often situated peripherally; body scales present, with two or more morphotypes arranged in two or more layers; some species toxic to fish and other gill-breathing animals; some are heterotrophic.

Prymnesium is a genus of haptophytes, including the species Prymnesium parvum. The genus is a unicellular motile alga. It is ellipsoidal in shape one flagellum is straight and there are two longer ones which enable movement.

The name Latinizes the Greek prymnēsion ‘cable (for mooring)’, from prymna ‘stern’, from prymnos ‘hindmost’.