Morphological Variation of Lingulodinium polyedrum (Dinophyceae) in Culture Specimens and Reinterpretation of the Thecal Formula

Abstract

Morphological observation of a unialgal culture of Lingulodinium polyedrum was conducted under light- andscanning electron microscopes. Lingulodinium polyedrum was redefined as having the thecal formula of APC, Q, 5',6", 6c, 6s, 5'", 2"" using the reinterpreted tabulation system. In our tabulation system, the Q, which is equivalent tothe 3' in the strict Kofoidean system, was treated as an auxiliary platelet because of its considerable morphologicalvariations in culture specimens. Subsequently, apical plates were redefined as plates directly connected to the APCand/or the Q. The 1"' and the 1p in the conventional Kofoidean system were treated as a component of the sulcus(the Ssa) and as an antapical plate (the 1""), respectively. Our reinterpreted tabulation system clearly differentiatedextant gonyaulacalean taxa.