Pseudo-nitzschia pungens var. cingulata var. nov. (Bacillariophyceae) based on field and culture observations

Abstract

AbstractPseudo-nitzschia pungens var. cingulata var. nov. (Bacillariophyceae) is described based on light and scanning electron microscopy of field and cultured material from Monterey Bay, California. Cultures of P. pungens (Grunow in Cleve & Moller) Hasle from widely separated coastal regions were studied for comparison. Pseudo-nitzschia pungens var. cingulata differs from P. pungens with regard to the fine structure of the valve and band striae. The valvar striae are composed of two widely spaced rows of poroids and often include a third incipient row. In contrast to the nominate variety, poroids are obscured by adjacent costae and are not commonly visible by light microscopy. Unlike P. pungens, which has a transverse row of large poroids in the band striae, the striate bands of this new variety are perforated by two rows of two or three minute poroids and one or two poroids closer to the band extremity. The neurotoxin domoic acid was not detected in any of the P. pungens var. cingulata cultures tested, although P. multiseries (Hasle) Hasle and P. australis Frenguelli did produce it under the same conditions.