Abstract
Marine benthic dinoflagellates are interesting not only because some epiphytic genera can cause harmful algal blooms but also for understanding dinoflagellate evolution and diversification. Our understanding of their biodiversity is far from complete, and many thecate genera have unusual tabulation patterns that are difficult to relate to the diverse known phytoplankton taxa. A new sand-dwelling genus, Pachena gen. nov., is described based on morphological and DNA sequence data. Three species were discovered in distant locations and are circumscribed, namely, P. leibnizii sp. nov. from Canada, P. abriliae sp. nov. from Spain, and P. meriddae sp. nov. from Italy. All species are tiny (about 9-23μm long) and heterotrophic. Species are characterized by their tabulation (APC 4' 3a 6'' 5c 5s 5''' 2''''), an apical hook covering the apical pore, an ascending cingulum, and a sulcus with central list. The first anterior intercalary plate is uniquely "sandwiched" between two plates. The species share these features and differ in the relative sizes and arrangements of their plates, especially on the epitheca. The ornamentation of thecal plates is species-specific. The new molecular phylogenies based on SSU and LSU rDNA sequences contribute to understanding the evolution of the planktonic relatives of Pachena, the Thoracosphaeraceae.
Highlights
Dipartimento di Architettura, Design e Urbanistica, University of Sassari, Via Piandanna 4, Sassari 07100, Italy Agenzia Ricerca per l’Agricoltura (AGRIS), Loc Bonassai, Olmedo, Sassari 07100, Italy
Pachena is characterized by its tabulation (APC 40 3a 600 5c 5s 5000 20000), the apical hook covering the apical pore and pointing to the left dorsal cell side, and the ascending cingulum (Fig. 10)
The sulcus has an internal list in its center that is part of the anterior and right sulcal plate
Summary
Dipartimento di Architettura, Design e Urbanistica, University of Sassari, Via Piandanna 4, Sassari 07100, Italy Agenzia Ricerca per l’Agricoltura (AGRIS), Loc Bonassai, Olmedo, Sassari 07100, Italy. Marine benthic dinoflagellates are interesting because some epiphytic genera can cause harmful algal blooms and for understanding dinoflagellate evolution and diversification. Our understanding of their biodiversity is far from complete, and many thecate genera have unusual tabulation patterns that are difficult to relate to the diverse known phytoplankton taxa. The first anterior intercalary plate is uniquely “sandwiched” between two plates The species share these features and differ in the relative sizes and arrangements of their plates, especially on the epitheca. Lane (Associate Editor) based on SSU and LSU rDNA sequences contribute to understanding the evolution of the planktonic relatives of Pachena, the Thoracosphaeraceae
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