Abstract
Pseudo‐nitzschia multistriata (Takano) Takano has been observed in seawater samples from the North Island and from the northern waters of the South Island, New Zealand, with blooms of >1.0 × 10 6 cells litre ‐1 being recorded in December 1997 (austral summer), and minor blooms occurring in both summer and winter 1998 and 1999. The species is notable for its sigmoid form, and for its cross‐reactivity with oligonucleotide probes targeted at P. australis Frenguelli ribosomal RNA. The species is non‐toxic, and for biotoxin monitoring purposes needs to be discriminated from the highly toxic P. australis . It falls in the “delicatissima” complex of Pseudo‐nitzschia H. Peragallo species, and electron microscopy shows a close resemblance to P. delicatissima (Cleve) Heidin, except for the lack of a central larger interspace.