Are Protoperidinium knipowitschii from the Sea of Azov and the Western Mediterranean P. paulseni (Dinoflagellata: Peridiniales) Synonymous?

Abstract

Thecal morphology and morphometry of the planktonic dinoflagellate Protoperidinium paulseni (Pavill.) Balech were studied in samples taken in the northwestern Black Sea (Odessa Bay). Using epifluorescence microscopy and SEM, data on the apical pore complex, apical intercalary, sulcal and cingular plates were obtained for the first time; the presence of the hypothecal pore in the 1”’ plate is also reported for the first time. The epitheca morphology was clarified (para 1’ and hexa 2a plates). Cells are 50.3-65.4 μm long and 38.5-52.4 μm wide (n=15). Light and scanning electron micrographs of the examined cells are presented. A comparison between the original descriptions and illustrations of P. paulseni, P. knipowitschii, our cells from Odessa Bay, as well as P. fatulipes and P. saltans (the species mentioned in the literature as morphologically similar to the former two), was made. The results showed that Protoperidinium knipowitschii (Usachev) Balech 1974 (basionym: Peridinium Knipowitschii Usachev 1927) described from the Sea of Azov can be considered synonymous to Protoperidinium Paulseni (Pavill.) Balech 1974 (basionym: Peridinium paulseni Pavill. 1909). Data on the geographical distribution of P. paulseni are provided.