Update of the Planktonic Diatom Genus Pseudo-nitzschia in Aotearoa New Zealand Coastal Waters: Genetic Diversity and Toxin Production

Domoic acid (DA) is produced by almost half of the species belonging to the diatom genus and causes amnesic shellfish poisoning (ASP). It is, therefore, important to investigate the diversity and toxin production of species for ASP risk assessments. Between 2018 and 2020, seawater samples were collected from various sites around Aotearoa New Zealand, and 130 clonal isolates of were established. Molecular phylogenetic analysis of partial large subunit ribosomal DNA and/or internal transcribed spacer regions revealed that the isolates were divided into 14 species ( , , , , , , , , , , , , , and cf. ). The and strains were further divided into two clades/subclades (I and II). Liquid chromatography-tandem mass spectrometry was used to assess the production of DA and DA isomers by 73 representative strains. The analyses revealed that two ( and ) of the 14 species produced DA as a primary analogue, along with several DA isomers. This study is the first geographical distribution record of , , , and in New Zealand coastal waters.