The species composition, morphology, and seasonal distribution of diatoms of the genus Attheya West, 1860 from the Sea of Japan

Abstract

Six species that belong to the diatom genus Attheya were found in the Russian waters of the Sea of Japan. A. cf. flexuosa is a new record for the seas of Russia. A. decora is recorded for the first time for the Sea of Japan. The peculiarities of the morphology of A. decora and A. cf. flexuosa are described and illustrated. The study of the seasonal distribution, abundance, and ecology of Attheya species in the northwestern Sea of Japan showed that A. longicornis and A. ussurensis were the most numerous and widespread species, reaching maximum densities (up to 1.5 × 10⁶ and 1.8 × 10⁴ cells/liter, respectively) in the spring, summer, and fall. A. cf. flexuosa and A. septentrionalis were rare and were found in low numbers in the winter and early spring. Based on the ultrastructure of the girdle bands, the form and number of chloroplasts, the presence/absence of rimoportula on the valve, and habitat features, we distinguished two groups of species of the genus Attheya from the Sea of Japan. The first group includes psammophytes A. decora, A. arenicola, and A. ussurensis; the second one comprises A. longicornis and A. cf. flexuosa epiphytic on other diatoms, as well as A. septentrionalis, which is found in the under-ice plankton and is able to attach to the underside of ice.