At this stage, they are between 20-24 μm in diameter. Taking a cross section of the flagella reveals both flagellar cross-sections as being smooth and spherical, unlike typical dinokaryote dinoflagellate cells, which have flagellar dimorphism (Skovgaard et al., 2009). In typical dinokaryote dinoflagellate cells, the transverse flagellum is ribbon-like and the axoneme runs along the longer, outer edge of the flagella, and a contractile fiber runs along the shorter, inner edge, while the other flagellum is spherical and smooth in cross section (Skovgaard et al., 2009). The cingulum is visible in both light microscopy and scanning electron microscopy (SEM) (Skovgaard et al., 2009). When looking at the dorsal side of the cell, the cingulum divides the cell into two equal parts, the hyposome and the episome (Skovgaard et al., 2009). However, when looking at the left lateral view of the cell, the hyposome appears twice as large as the episome (Skovgaard et al., 2009). The sulcus can be viewed as a shallow depression in SEM images of some cells (Skovgaard et al., 2009). It extends ventrally from the site of insertion of the longitudinal flagellum on the apical end of the cell to the posterior end of the cell (Skovgaard et al., 2009). The weak appearance of the cingulum and sulcus also make the morphology of "Ichthyodinium" sp. distinct from typical dinoflagellates, which tend to have a more pronounced cingulum and sulcus (Skovgaard et al., 2009). In a 2009 study, no mastigonemes were found on the flagella of the asymmetric I. chabelardi zoospores (Skovgaard et al., 2009). This contradicts observations from 2006, in which mastigonemes were reported on the posterior flagellum of spherical zoospores (Gestal et al., 2006). It is possible that this discrepancy is the result of the two different cell types having flagella of different morphology, or the result of the flagella in the 2009 study being damaged during fixation (Skovgaard et al., 2009). "Ichthyodinium" sp. has been reported in a large number of fin fish species of Europe and Asia.