Morphology, ultrastructure and molecular phylogeny of cyst-producing Caladoa arcachonensis gen. et sp. nov. (Peridiniales, Dinophyceae) from France and Indonesia

ABSTRACTThe dinoflagellate order Peridiniales encompasses several well circumscribed families. However, the family level of some genera, such as Bysmatrum and Vulcanodinium, has remained elusive for many years. Four Peridinium-like strains were established from the Atlantic coast of France and North Sulawesi, Indonesia through cyst germination or isolation of single cells. The cyst-theca relationship was established on specimens from the French Atlantic. Their morphologies were examined using light, scanning and transmission electron microscopy. The cells were characterized by a much larger epitheca relative to the hypotheca, a large anterior sulcal (Sa) plate deeply intruding the epitheca and a small first anterior intercalary plate. The plate formula was identified as Po, cp, X, 4′, 3a, 7′′, 6C, 5S, 5′′′, 2′′′′, shared by Apocalathium, Chimonodinium, Fusiperidinium and Scrippsiella of the family Thoracosphaeraceae but the configuration of Sa plate and anterior intercalary plates is different. Transmissi...