A new diplopsalid species Oblea acanthocysta sp. nov. (Peridiniales, Dinophyceae)

Oblea acanthocysta of the diplopsalid group is described as a new species from Omura Bay, West Japan. The motile cells are subspherical, have a large sulcal list at the left margin, and are characterized by the plate formula, Po, X, 3′, 1a, 6″, 3c+t, 6s?, 5?, 2″″. The species resembles Oblea torta in shape and plate distribution, but is smaller and differs in the shape of plate 1′ and position of plate 1a. Resting cysts of O. acanthocysta are spherical and pale brown in color, possess many hollow acuminate spines, and have a theropylic archeopyle. In the SSU rRNA gene sequences of three cells of O. acanthocysta and two cells of O. torta, no intraspecific base substitutions were detected within either species. Based on phylogenetic analyses, the O. acanthocysta clade is included in the diplopsalids clade together with other diplopsalid species such as O. torta, Diplopsalis lebourae, Diplopsalopsis bomba and Gotoius excentricus. The sequences of O. acanthocysta are different from those of O. torta in 154 base pair substitutions, but O. acanthocysta and O. torta have a very close phylogenetic relationship

MORPHOLOGY OF A NEW HETEROCAPSA SPECIES (PERIDINIALES, DINOPHYCEAE) OCCURED IN HUE, VIETNAM

To investigate the distribution of Heterocapsa including a harmful species H. circularisquama, cells were surveyed in three Vietnamese coasts, Ha Long Bay, Hue and Phu Quoc Island in 2006. Cells of Heterocapsa were detected from Lang Co Lagoon and adjacent coast in Hue. Cell of the species possesses thecal plates corresponding to the typical of Heterocapsa. Under TEM, body scales approximately 500 nm in diameter are observed. The scale structure is similar to that of H. illdefina, however, number of the marginal spine is different. We concluded it is an undescribed Heterocapsa species possessing a new body scale ultrastructure

A new heterotrophic dinoflagellate from the North-eastern Pacific, Protoperidinium fukuyoi: cyst–theca relationship, phylogeny, distribution and ecology

The cyst-theca relationship of Protoperidinium fukuyoi n. sp. (Dinoflagellata, Protoperidiniaceae) is established by incubating resting cysts from estuarine sediments off southern Vancouver Island, British Columbia, Canada, and San Pedro Harbor, California, USA. The cysts have a brown-coloured wall, and are characterized by a saphopylic archeopyle comprising three apical plates, the apical pore plate and canal plate; and acuminate processes typically arranged in linear clusters. We elucidate the phylogenetic relationship of P. fukuyoi through large and small subunit (LSU and SSU) rDNA sequences, and also report the SSU of the cyst-defined species Islandinium minutum (Harland & Reid) Head etal. 2001. Molecular phylogenetic analysis by SSU rDNA shows that both species are closely related to Protoperidinium americanum (Gran & Braarud 1935) Balech 1974. Large subunit rDNA phylogeny also supports a close relationship between P. fukuyoi and P. americanum. Three subgroups in total are further characterized within the Monovela group. The cyst of P. fukuyoi shows a wide geographical range along the coastal tropical to temperate areas of the North-east Pacific, its distribution reflecting optimal summer sea-surface temperatures of similar to 14-18 degrees C and salinities of 22-34psu

Morphology and taxonomy of chain-forming species of the genus Cochlodinium (Dinophyceae)

The morphology of an unarmored chain-forming harmful dinoflagellate Cochlodinium polykrikoides and its similar species such as Cochlodinium catenatum, Cochlodinium fulvescens, and Cochlodinium convolutum was carefully observed, emphasizing the single cell stage for clarifying taxonomically important morphological features. To differentiate C. polykrikoides from C. convolutum, the shape and the position of the nucleus are useful characters. C. polykrikoides also differs from C. fulvescens in being smaller in size, possessing many rod-shaped chloroplasts and having the sulcus running just below the cingulum on the dorsal surface. Careful observation of the ichnotype of C. catenatum suggests that C. catenatum sensu Kofoid and Swezy collected from off La Jolla, CA, USA, is not identical to C. catenatum sensu Okamura and is probably a different species, in having no chloroplasts and a nucleus positioned at the center of the cell. In addition, C. polykrikoides has many morphological features in common with C. catenatum sensu Okamura except for slightly elongate cells and is probably a junior synonym of this species