Prorocentrum glenanicum sp nov and Prorocentrum pseudopanamense sp nov (Prorocentrales, Dinophyceae), two new benthic dinoflagellate species from South Brittany (northwestern France)

Two new marine benthic Prorocentrum species, Prorocentrum glenanicum sp. nov. and Prorocentrum pseudopanamense sp. nov., are described from sandy sediments of South Brittany (northwestern France). The morphology was examined using light and scanning electron microscopy, and the molecular phylogeny was inferred from sequences of the small ribosomal subunit (SSU rDNA). Morphologically, cells of Prorocentrum glenanicum sp. nov. have a broadly oval to circular shape and measure 30-33 mu m in length and 29-31 mu m in width. Prorocentrum pseudopanamense sp. nov. is slightly asymmetrically oval, 46-51 mu m long and 44-47 mu m wide. The theca of Prorocentrum glenanicum sp. nov. is smooth and ornamented with shallow circular depressions containing a pore while it is areolated in Prorocentrum pseudopanamense sp. nov. Both species exhibit an asymmetric ornamentation between left and right valves. In Prorocentrum glenanicum sp. nov., two distinct groups of areolae are observed on the right valve only: a group of about 20 is located just above the centre of the valve, and another dense group is present in the posterior part of the cell. In Prorocentrum pseudopanamense sp. nov., a large depression containing several pores is present in the posterior part of the valves. In both species, the periflagellar area comprises nine platelets and is very slightly excavated. The molecular analysis confirmed the establishment of the taxa as new species. In the molecular tree inferred from SSU rDNA they grouped with Prorocentrum panameave and formed a distinct group within clade 1 of Prorocentrum, which comprised mostly asymmetric species.