Detection of the widespread presence of the genus Ansanella along the Catalan coast (NW Mediterranean Sea) and the description of Ansanella catalana sp. nov. (Dinophyceae)

Many dinoflagellate groups have been overlooked because of their small size compared with their larger counterparts; consequently, little is known about their diversity, distribution, and contribution to the planktonic community. Ansanella is a recently described genus of small marine planktonic dinoflagellates belonging to the order Suessiales. In this study, morphological observations together with molecular SSU and LSU rDNA analyses of clonal strains from the Catalan coast (NW Mediterranean Sea) allowed the identification of A. cf. natalensis and a newly reported species, Ansanella catalana. The cells of A. catalana are oval and 9.6-15.5 mu m long; the cell surface is covered with amphiesmal vesicles arranged in 10-13 latitudinal rows; the episome has an apical furrow complex with a single elongated apical vesicle; a type E eyespot is also present. This newly identified species can be distinguished from congeneric species by morphological details of the cell surface, the presence of mucocysts and an extrusome type not previously reported in dinoflagellates. The characterization of this structure could provide insights into extrusome evolution in dinoflagellates. Metabarcoding analysis of plankton and sediment samples from the Catalan coast revealed a wide distribution of Ansanella and the remarkable contribution of this genus to the dinoflagellate communities from three different coastal habitats. Highlights Members of Ansanella genus are widespread along the Catalan coast. A new species of the genus Ansanella (Dinophyceae) is described. A new type of extrusome was observed.