Nanoplankton protists from the western Mediterranean Sea. II. Cryptomonads (Cryptophyceae = Cryptomonadea)

This paper is an electron microscopical account of cryptomonad flagellates (Cryptophyceae = Cryptomonadea) in the plankton of the western Mediterranean Sea. Bottle samples collected during the spring-summer of 1998 in the Sea of Alboran and Barcelona coastal waters contained a total of eleven photosynthetic species: Chroomonas (sensu auctorum) sp., Cryptochloris sp., 3 species of Hemiselmis, 3 species of Plagiosehmis including Plagiosehmis nordica stat. nov/sp. nov., Rhinomonas reticulata (Lucas) Novarino, Teleaulax acuta (Butcher) Hill, and Teleaulax amphioxeia (Conrad) Hill. Identification was based largely on cell surface features, as revealed by scanning electron microscopy (SEM). Cells were either dispersed in the water-column or associated with suspended particulate matter (SPM). Plagioselmis prolonga was the most common species both in the water-column and in association with SPM, suggesting that it might be a key primary producer of carbon. Taxonomic keys are given based on SEM.