Diversity and morphology of calcareous dinophytes (Thoracosphaeraceae, Peridiniales)
Dinophytes are unicellular eukaryotic algae that, together with their closest relatives, ciliates and apicomplexans, belong to the superphylum of alveolates. Some of them, namely calcareous dinophytes (Thoracosphaeraceae, Peridiniales), develop an immotile calcareous cell during their life history. They accumulate in the oceans’ sediments analogously to terrestrial seed banks. Although the diversity of calcareous dinophytes was investigated in several studies, only a few of them provide data from coastal waters and sediments. The main goal of this thesis was to record the diversity of calcareous dinophytes from marine environments using morphological, anatomical, taxonomical and evolutionary approaches. An essential part of the project was to establish living dinophyte cultures, assuring constant access to fresh material for morphological and molecular analysis (chapters 1-5). The morphological diversity of extant species as well as those described from the fossil record was documented (chapter 1), and the conflict between molecular and the morphological data was presented (chapter 1-5). Furthermore, detailed morphological descriptions of two new species, Scrippsiella bicarinata und S. kirschiae (chapter 2) and morphological analysis of Bysmatrum sp., a species of doubtful phylogenetic position (chapter 4), were provided. Scrippsiella trochoidea (basionym: Glenodinium trochoideum), a species with a previously ambiguous description, has been redescribed and epitypified by myself based on material collected from the type locality to assure a reliable determination of this species (Chapter 3). Comparative ultrastructure investigations using light and electron microscopic techniques at various stages of the life cycle showed that the anatomical structure during the biomineralization processes differs within subgroups of calcareous dinophytes (chapter 5) and could be used as a useful phylogenetic trait.