Article: Nomenclature and homology in peridinialean dinoflagellate plate patterns

The apical and antapical series of peridinialean dinoflagellate thecal plates are redefined relative to the cingulum. They are then compatible with the Kofoidian pre- and postcingular series, and the need to recognize anterior and posterior intercalary series is removed. The concept of apical closing and antapical closing series is introduced. Homologous and corresponding plates are recognized in fifteen selected modern and fossil dinoflagellates by comparing interseries relationships with respect to a model plate pattern. The differences between the selected patterns are due to three variable effects. First, the reduction in plate number through simplification, where one plate in one pattern corresponds to two or more plates in another pattern. This critically affects interseries relationships. Secondly, the primary development of fewer plates without affecting interseries relationships. Thirdly, the variation in the relative size of certain plates. The interaction of these three effects resulted in the comparatively independent evolution of epithecae and hypothecae. Reduction in over-all plate number, particularly through the primary development of fewer plates, may well represent a fundamental trend in the evolution of peridinialean plate patterns.