A survey for body scales in dinoflagellates and a revision of Cachonina and Heterocapsa (Pyrrhophyta)

Small organic scales 0.2 to 0.4 ?m in diameter have been observed to form a layer on the surface of three species of marine dinoflagellates. Two of the species were originally described as members of the genus Cachonina; the third is Heterocapsa pygmaea Loeblich et al., 1981. The body scales are very similar to those previously described covering cells of Heterocapsa triquetra (Ehrenberg)Stein, 1883. These scales are freely shed from the cells of the above four species and can be found in the culture medium; no scales were observed in the culture medium of 35 other dinoflagellate species representing 18 genera and 11 families. The complete thecal plate pattern of H. triquetra, type species of Heterocapsa, has been determined, and on the basis of similarities in body scale morphology and thecal plate tabulation, the genus Cachonina is placed in the synonomy of Heterocapsa. Cachonina illdefina and C. niei are transferred to Heterocapsa.