Formonsella pyramidosa (Haptophyta, Papposphaeraceae): a new weakly calcified coccolithophore genus from warm-water regions

Abstract. A new species Formonsella pyramidosa gen. et sp. nov. is described to accommodate a widely distributed warm-water coccolithophore species that has previously been referred to as Pappomonas sp. 2. Formonsella differs from Pappomonas with respect to, in particular, the detailed structure of the rim on both calicate and non-calicate coccoliths. In Formonsella the rim comprises two cycles of rod-shaped elements. Although elements in the distal layer are higher at one end, giving this cycle a serrate outline, the overall appearance is very different from the Pappomonas rim which encompasses a distal cycle of pentagonal elements, giving the rim a very distinct toothed appearance. Inverted rectangular pyramidal structures terminate the calicate F. pyramidosa coccoliths. In non-calicate coccoliths the central area calcification comprises differently sized tile-shaped elements, mostly arranged along the longitudinal axis in a rather irregular way.