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As part of a long-term study of benthic dinoflagellates from the Belizean barrier reef system, we report a new species: Prorocentrum levis M. A. Faust, Kibler, Vandersea, P. A. Tester et Litaker sp. nov. P. levis cells are oval in valve view and range in size from 40 to 44 μm long and 37 to 40 μm wide. Each valve surface is smooth, with 221–238 valve pores and 99–130 marginal pores. These pores are uniformly small and range in diameter from 0.13 to 0.19 μm. Asexual reproduction in P. levis is atypical, occurring within a hyaline envelope, and produces long branching chains of adherent cells. A phylogenetic analysis of SSU rDNA indicated that of the Prorocentrum species sequenced so far, P. levis was most closely related to P. concavum. P. levis produces okadaic acid and dinophysis toxin-2 (DTX2). Further, SEM observations and SSU rDNA sequence for P. belizeanum M. A. Faust, which was isolated at the same time, are also presented. [ABSTRACT FROM AUTHOR]

Two new heterotrophic Protoperidinium species are described from oceanic waters from The Gulf Stream, SW Atlantic Ocean and Belizean Atlantic Barrier Reef Ecosystems, Caribbean Sea. Protoperidiniurn novella Faust sp. nov. and P. concinna Faust sp. nov. show a plate formula of 4′, 1a, 7″, 4C(3+t), 6S, 5‴, and 2‴, which is atypical for the genus. It is characterized by a miniscule flat closure on the extreme anterior of the pointed apical horn. Apical pore complex is absent. Apical ventral plate 1′ disconnects from the tip of the apical horn and connects directly to the anterior sulcal plate (Sa) along a straight line of the longitudinal axis of the cell's sagittal plane. The shape and position of the intercalary plate (1a) is another distinctive feature for these species, the presence of only one 1a plate. The thecal plate features of P. novella and P. concinna justifies the establishment of the new subgenus, Testeria Faust subgen, nov. The relationship with other congeneric species and the position within the genus Protoperidinium are discussed. [ABSTRACT FROM AUTHOR]

Three new bwnthic, photosynthetic dinoflagellate species, Prorocentrum norrisianum, from floating detritus and coral rubble of Central America are described from scaning electron micrographs. Species were identified based on shape size surface micromorphology ,thecal plate ornamentation, and architecture of the perflagellar area and intercalary band. Cells of P. norrisianum are avate with a cell size of 20-25 μm long and 13-16 μm wide. The theca is delicate its surface smooth, pores species specific with 95-105 pores per valve, Pores are round with a diameter of about 0.1 μm The periflagellar area is V-shaped located on the right valve in a shallow depression. It has no ornamentation.The flagellar and auxiliary pores are unequal in size. The interacalry band is smooth. Proroentrum tropicalis cells are avoid, 50-55 μm long and 40-45 μm wide in valve view with maximum width behind the middle region, narrow at the right valve, is a V-shaped periflagellar area, situated in the right valve, is a V-shaped wide triangle with a deeply indented depression; the left valve exhibits a flat ridge. The periflagellar area is unornamented and the flagellar and auxiliary pores are unequal is size. The valve surface is rugose with evenly distributed galve poroids. Each poroid appears to have a small dome in the center. The intercalary band is rimlike around the cell margin, granulated and horizontally striated. Prorocentrum reticultum cells are oblong in valve view cells are 55-60 μm long and 40-45 μm wide .Thermal surface is reticulated it is composed of a labyrinth of ridges with alternating depressions that wavy in size and shape. Each depression has a narrow ablong kidney shaped opening about 0.6 μm long.The periflagellar area is a deep V-shaped trangle. The right valve of P reticulam is excavated and contains a large flagellar pore and a smaller auxi,iiary pore surrounded by a barrow optical collar.The left valve margin edhinits a curved flat ridge.The intercalary band is smooth. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive examination of the taxonomy of the genus Ostreopsis Schmidt. The morphology of six species of marine dinoflagellates, Ostreopsis siamensis Schmidt 1902, Ostreopsis lenticularies Fukuyo 1981, Osteropsis ovata Fukuyo 1981, Ostreopsis heptagona Norris, Bomber, et Balech 1985, Ostreopsis mascarenensis Quod 1994, from three geographical regions (Japan, Southwest Indian Ocean, and the Caribbean) and three marine habitats (sand, water column, and macroalgal surfaces) are described from scanning electron micrographs. Differences in the following morphological characteristics differentiated the species: cell shape and size, and ornamentation of the epitheca, cingulum, and hypotheca. The thecal plate formula of six Ostreopsis species is P[suba], 3',7", 6C, 6S?, V[subP], R[subP] 5"', 1P, 2"", with differences in thecal plate size and shape. The cingulum in ventral view has two prominent structures: a ventral plate (V[subp]) with a ventral pore (V[aubo]) and a ridged plate (R[subp]) that distinguishes Ostreopsis species from any other dinoflagellate taxa. This paper also includes ecological and toxicity information regarding the six Ostreopsis species. [ABSTRACT FROM AUTHOR]

The thecal surface morphology of Scrippsiella subsala (Ostenfeld) Steidinger et Balech was examined using the scanning electron microscope. This species is distinguished by a number of morphological characteristics. Aplcal plate 1' is wide, asymmetric, and pentagonal, and it ends at the anterior margin of the cingulum. Intercalary plates 2a and 3a are separated by apical plate 3'. The apical pore complex includes a large P[SUBa] plate with a raised dome at the center and a deep canal plate with thickened margin at plates 2', 3', and 4'. The intercalary bands are wide and deeply striated. The cingulum is deep, formed by six cingular plates; its surface is transversely striated and aligned with a row of minute pores. The cingular list continues around postcingular plate 1[SUPm] to form a sulcal list. The sulcal list is a flexible ribbon with a rounded tip that protrudes posterioly, partially covering the sulcal plates. The hypotheca is lobed, and the antapical plates are irregularly shaped and wide in antapical view: The thecal surface is vermiculate to reticulate. A comparison in morphology and ecology is presented between S. subsalsa and other known Scrippsiella species. [ABSTRACT FROM AUTHOR]

Dinoflagellate associations, including toxic and potentially toxic benthic species, were examined in sand from South Water Cay and Carrie Bow Cay, Belize. The inshore sand habitat in localized areas of warm shallow lagoonal waters supported blooms of toxic assemblages of dinoflagellates. In the sand, the dominant microalgae were dinoflagellates; cyanobacteria were a minor component and diatoms were absent. Ciliates and nematodes were present. Assemblages of microorganisms in colored sand were examined for 4 consecutive days after which a storm washed away the patch. The sand-dwelling dinoflagellate assemblage included 16 species where densities ranged from as low as 1.3% to 15% of total cell densities. The dominant species was Scrippsiella subsalsa, having 1.8 × 10[sup5] to 2.3 × 10[sup5] cells · g[sup-1 sand. Toxic dinoflagellates indentified in the sand were Gambierdicus toxicus, Ostreopsis lenticularis, Prorocentrum lima, Prorocentrum mexicanum, and Amphidinum carteri. The potentially toxic Ostreopsis labens, Gambierdiscus belizeanus sp. nov., and Coolia tropicalis sp. nov. were also identified. Toxic and potentially toxic species represented 36% to 60% of total microalgal cell assemblage. The morphology of a new sand-dwelling species, Gambierdiscus belizeanus sp. nov., was examined with the scanning electron microscope. The plate formula was P[subo], 3′, 7′′, 6c, 8s?, 5′′′, 1p, and 2′′′′. Dimensions of G. belizeanus cells were 53-67 μm long, 54-63 μm wide, and 92-98 μm in dorsoventral depth. Cells were deeply areolated, ellipsoid in apical view, and compressed anteroposteriorly. The cells of G. belizeanus were identified by the cell's long, narrow, pentagonal, posterior intercalary plate (1p) wedged between the wide postcingular plates 2′′′ and 4′′′; 1p occupied 20% of the width of the hypotheca. The plate formula for Coolia tropicalis sp. nov. was P[subo], 3′, 7′′, 7c, 8s?. 5′′′, and 2′′′′. Cell size ranges were 23-40 μm long, 25-39 μm wide, and 35-65 μm in dorsoventral diameter. Cells were spherical, smooth, and covered with scattered round pores. The epitheca was smaller than the hypotheca. Precingular plates 1′ and 7′′ were small and narrow, and the first apical plate 1′ and precingular plate 6′′ were the largest plates on the epitheca. The apical pore was straight and 7 μm long, and was situated in the apical plate complex. Cells of C. tropicalis were distinguished from C. monotis by the wedge-shaped plate 1′, a four-sided 3′ plate, and a short apical pore. [ABSTRACT FROM AUTHOR]

Three new benthic, sand-dwelling dinoflagellate species, Prorocentrum sabulosum, prorocentrum scuptile, and prorocentrum arenarium, from coral rubble are described from scanning electron micrographs. Species were identified based on shape, size, surface micromorphology, ornamentation of thecal plates, and architecture of the periflagellar area and intercalary band. Cells of P. sabulosum are oval with a cell size of 48-50 μm long and 41-48 μm wide. The areolae are round to oval and numerous (332-450 per valve) and range from 1 to 1.6 μm in size. The periflagellar area of P. sabulosum bears a wide V-shaped depression with a flat ridge and lacks ornamentation; it accommodates six pores: one large flagellar pore, an adjacent smaller auxiliary pore, and four pores of unknown function. The flagellar and auxiliary pores are surrounded by a narrow apical collar. The intercalary band of P. sabulosum is smooth. Prorocentrum sculptile cells are broadly oval, 32-37 μm long, and 30-32 μm wide in valve view with a deep-sculptured apical area. 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 μm in diameter). The periflagellar area is V0shaped with a deeply indented depression; it accommodates the two flagella and a thin angled apical plate. The intercalary band is smooth. Prorocentrum arenarium cells are nearly round in valve view 30-32 μm in diameter. Thecal 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 μm and 0.36 μm, respectively. The periflagellar area is an unornamented, broad triangle into which a large flagellar pore and a smaller auxiliary pore are fitted. Both flagella, longitudinal and transverse, protrude from the flagellar pore. The intercalary band is smooth. The presence of a peduncle-like structure (2-3 μm long) in P. arenarium was observed situated in the flagellar pore. [ABSTRACT FROM AUTHOR]

This study indicates that bilaterally flattened, armored, benthic dinoflagellates are more diverse in morphology than previously known. A new species, Plagiodinium belizeanum Faust et Balech gen. et sp. nov., is described in floating detritus from Twin Cays, Belize, mangrove habitats. Plagiodinium belizeanum cells are small, with dimensions of 26.5-30.5 μm in length, 20-24.5 ???m in width, and 6.5-8.5 μm in depth. Cells are ablong and bilaterally compressed with a posteriorly located, spherical nucleus, many chloroplasts, and spherical starch granules. The epitheca descends ventrally, is cap-shaped, and is composed of five plates and a very small platelet provisionally named P??? situated in the center. The epitheca is narrowly oval in opical view with a pointed truncated ventral side and a rounded dorsal side. The cingulum is composed of five plates. The hypotheca is constructed of five posteriorly elongated postcingular plates and one antapical plate. The sulcus is very short and narrow, comprised of five small plates. The thecal plate arrangement of P. belizeanum is P[SUB0] 5', O′, 5C, 1′′, 5S. No lists are present. Thecal plates have a smooth surface with small and irregularly scattered pores. The intercalary bond is smooth on the outer cell surface and broadly striated on its inner surface. We conclude that P. belizeanum represents a new, benthic, peridinioid, armored genus, Plagiodinium gen. nov. The taxonomic position of P. belizeanum sp. nov. is compared to related sand-dwelling and bilaterally flattened benthic dinoflagellates [ABSTRACT FROM AUTHOR]