The taxonomy and ultrastructure of Chrysochromulina simplex (Prymnesiophyceae)

Abstract

The type description of Chrysochromulina simplex Estep et al. (Prymnesiophyceae) is emended, based on clonal cultures from the southern Indian Ocean. Cells possess a single scale type (0.3–0.58 μm in diameter) with faint concentric markings on the distal face and 21–36 radiating ridges with an excentric cross on the proximal face. The long, coiling haptonema (max. 79 μm) and the two heterodynamic flagella (11–16 μm) are inserted on the concave face of the saddle-shaped cells. The flagellar apparatus consists of four microtubular roots (R1 of 6+4, a single-stranded R2, a bifurcated R3 of 2/2+1, a single-stranded R4) and various fibrous connectives (distal band with extensions to the R 1 and over the R2, a proximal band, three accessory bands). The ultrastructure of the flagellar apparatus shares features with both C. apheles Moestrup et Thomsen and C. acantha Leadbeater et Manton, and intra-and intergeneric comparisons are made.