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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]

A new marine heterotrophic dinoflagellate species, Protoperidinium belizeanum sp. nov., from a coral reef-mangrove pond was identified from scanning electron micrographs. Recognition of this new species was based on unique features of the thecal morphology, which included cell size and shape, presence of short and wide postcingular plates, sulcal architecture, antapical spines, and intricate thecal plate patterns of ridged hexagonal depressions. The thecal plate formula is as follows: Po, X, 4′, 3a, 7″, 4C (3+t), 6S, 5‴, 2″″. Species association of P. be-lizeanum sp. nov. within the genus Protoperidinium , its habitat, and associated dinoflagellates species are discussed. [ABSTRACT FROM AUTHOR]

A new marine heterotrophic dinoflagellate species, Protoperidinium belizeanum sp. nov., from a coral reef-mangrove pond was identified from scanning electron micrographs. Recognition of this new species was based on unique features of the thecal morphology, which included cell size and shape, presence of short and wide postcingular plates, sulcal architecture, antapical spines, and intricate thecal plate patterns of ridged hexagonal depressions. The thecal plate formula is as follows: Po, X, 4′, 3a, 7″, 4C (3+t), 6S, 5‴, 2″″. Species association of P. be-lizeanum sp. nov. within the genus Protoperidinium , its habitat, and associated dinoflagellates species are discussed. [ABSTRACT FROM AUTHOR]

A new species of planktonic dinoflagellate, Prorocentrum arabianum isolated from the Gulf of Oman, is described using both scanning electron microscopy (SEM) and light microscopy. This clonal isolate has the following morphological characteristics: (1) cell shape is asymmetric; (2) thecal surface is rugose, covered with small poroids; (3) periflagellar area is unornamented, and (4) intercalary band is horizontally striated. Analysis of P. arabianum confirms the production of one cytotoxic compound and one ichthyotoxic compound. P. arabianum is the second known toxic planktonic Prorocentroid dinoflagellate. [Copyright &y& Elsevier]

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]

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]

Three new benthic dinoflagellate species. Prorocentrum belizeanum, Prorocentrum elegans, and Pro-rocentrum caribbaeum, from mangrove floating detritus 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. belizeanum are round to slightly oval with a cell site o.[55-60 urn long and 50-55 μ wide. Areolae are round and numerous (855-1024 per valve)and range from 0.66 to 0.83 μm in site. The periflagellar area of P. belizeanum is a broad V-shaped depression; it accommodates a flagellar and an auxiliary pore and a flared, curved apical collar. The intercalary band of P. belizeahum is horizontally striated. Prorocentrum elegans is a small species 15-20 μmlong and 10-14 μm wide, with an ovate cell shape. The thecal surface is smooth. Two sites of value pores were recognized: large, round pores (20-22 per valve) arranged in a distinct pattern and smaller pores situated in an array along the intercalary band. The periflagellar area is V-shaped; it accommodates an uneven sited flagellar pore, an auxiliary pore, and an angled protuberant flagellar plate. The intercalary band is transversely striated. It is a bloom.forming species. Prorocentrum caribbaeum cells are heart-shaped with a rounded anterior end and a pointed posterior end. Cells range from 40 to 45 tun long and 30 to 35 μm wide. Thecal surface has two different-sized pores: large, round pores (145-203 per valve) arranged perpendicularly from the posterior margins, and small, round pores unevenly distributed on the thecal surface. The periflagellar area is ornate. It is V. shaped with a curved apical collar located next to the auxiliary pore; a smaller protuberant apical plate is adjacent to the flagellar pore. The intercalary band is transversely striated and sinuous. Cells are active swimmers. [ABSTRACT FROM AUTHOR]