THE GENUS THALASSIOSIRA (BACILLARIOPHYTA) - T-CEDARKEYENSIS, A NEW MARINE BENTHIC DIATOM FROM THE FLORIDA COAST OF THE GULF-OF-MEXICO

A new diatom species, Thalassiosira cedarkeyensis, is described associ ated with artificial reef substrate from Cedar Key waters off the Flor ida coast in the north-eastern Gulf of Mexico. T. cedarkeyensis can be differentiated by its extremely small cells (7.5-9.5 mum in diameter) , tangentially undulated valves, restriction of occluded processes and the distal end of the rimoportula to the convex part of the valve, th e presence of a marginal ring of fultoportulae and a single subcentral fultoportula, each process with four satellite pores and four struts. The epicingulum is composed of 5-6 open, perforated bands, whose open ings are offset to the right (dextral symmetry). The valve mantle is b ordered by a hyaline vertical rim and is 3 areolae high. The new speci es is compared with morphologically similar forms. The present report is the first record of a plicated species of Thalassiosira from the Gu lf of Mexico.