Morphology, Molecular Genetics and Potential Importance for Mucilage Events of the New Coccolithophorid <i>Ochrosphaera neapolitana</i> in the Sea of Marmara

The coccolithophorid Ochrosphaera neapolitana was reported for the first time from samples obtained during a large-scale mucilage event in the Sea of Marmara in May 2022 in a previous study. We also found this species in our samples obtained about a year ago (i.e., in June 2021). In our study, O. neapolitana was further isolated and produced in the laboratory as a monoculture for further investigations using electron microscopy and molecular methods. Ochrosphaera neapolitana was identified using a small sub-unit (SSU) rRNA sequence and subsequent phylogenetic analysis. During the laboratory experiments, O. neapolitana was surprisingly observed to produce conspicuous levels of mucilage as a skim layer in mono- or multi-species cultures, mainly comprising other diatom species. This observation could be a significant milestone in understanding the reasons and mechanisms of mucilage events that occur in the Sea of Marmara.