Heterothallism and thecal development in the sexual life history of Peridinium volzii (Dinophyceae)

Abstract

Sexual reproduction was induced in the dinoflagellate Peridinium volzii Lemmermann when exponentially growing cells were inoculated into nitrogen deficient medium. Sexual reproduction was isogamous and heterothallic with two mating types identified, one designated plus, the other minus. Post-zygotic cells carried either the plus or minus factor. Meiosis, therefore, was zygotic. Scanning electron microscopy showed planozygote enlargement and thecal distortion due to unequal enlargement of intercalary bands between plates. Enlarged intercalary bands were shown to be heavily striated except for triangular junctions formed by the union of three intercalary bands.