Parmales (Chrysophyceae) from Mexican, Californian, Baltic, Arctic and Antarctic waters with the description of a new subspecies and several new forms

The Parmales, a recently established order of nanoplanktonic marine chrysophytes (sensu lato) characterized by a siliceous cell wall of five or eight plates arranged in symmetrical patterns, were examined from various localities with both TEM and SEM. Triparma laevis Booth subsp. mexicana Kosman subsp. nov. is described from the Sea of Cortez, together with a cell resembling Triparma retinervis Booth. A spined variant of Triparma retinervis subsp. crenata Booth, reported earlier from the California Current, was also observed in waters off California. Baltic forms of Triparma columacea Booth with highly convex shield plates are identical to forms described from the North Pacific. In addition to six formerly described forms, two new spined variants, and a new form of Triparma columacea subsp. alata Marchant (North Pacific form), are reported from antarctic waters. Plates belonging to Tetraparma pelagica Booth et Marchant were found in Disko Bay, Greenland. The placement of the above taxa in the classification scheme of the Parmales is extremely difficult due to the lack of knowledge about the parmalean life cycle, as well as their definite affinity to other taxonomic groups. This is the first report of Parmales from arctic and subtropical waters, indicating a worldwide distribution, thus emphasizing their possible importance in oceanic food webs and the need for further research.