3 NEW BENTHIC SPECIES OF PROROCENTRUM (DINOPHYCEAE) FROM CARRIE-BOW-CAY, BELIZE - P-SABULOSUM SP-NOV, P-SCULPTILE SP-NOV, AND P-ARENARIUM SP-NOV

Three new benthic, sand-dwelling dinoflagellate species, Prorocentrum sabulosum, Prorocentrum scuptile, and Prorocentrum arenarium,from cora l rubble are described from scanning electron micrographs. Species wer e identified based on shape, size, surface micromorphology, ornamentat ion of thecal plates, and architecture of the periflagellar area and i ntercalary band. Cells of P. sabulosum are oval with a cell size of 48 -50 mu m long and 41-48 mu m wide. The areolae are round to oval and n umerous (332-450 per valve) and range from 1 to 1.6 mu m in size. The periflagellar area of P. sabulosum bears a wide V-shaped depression wi th a flat ridge and lacks ornamentation; it accommodates six pores: on e large flagellar pore, an adjacent smaller auxiliary pore, and four p ores of unknown function. The flagellar and auxiliary pores are surrou nded by a narrow apical collar. The intercalary band of P. sabulosum i s smooth. Prorocentrum sculptile cells are broadly oval, 32-37 mu m lo ng, and 30-32 mu m wide in valve view with a deep-sculptured apical ar ea. The valves are smooth and are marked with shallow depressions (856 -975 per valve). Some of these depressions have a small round opening (0. 13 mu m in diameter). The periflagellar area is V-shaped with a de eply indented depression; it accommodates the two flagellar and a thin angled apical plate. The intercalary band is smooth. Prorocentrum are narium cells are nearly round in valve view 30-32 mu m in diameter. Th ecal surface is smooth with scattered kidney-shaped valve poroids (65- 73 per valve) and marginal poroids (50-57 per valve). Length and width of poroids are 0.62 mu m and 0.36 mu m, respectively. The periflagell ar area is an unornamented, broad triangle into which a large flagella r pore and a smaller auxiliary pore are fitted. Both flagella, longitu dinal and transverse, protrude from the flagellar pore. The intercalar y band is smooth. The presence of a peduncle-like structure (2-3 mu m long) in P. arenarium was observed situated in the flagellar pore.