Hisae Kawami

Cochlodinium fulvescens sp. nov. (Gymnodiniales, Dinophyceae), a new chain-forming unarmored dinoflagellate from Asian coasts

Cellular morphology and the phylogenetic position of a new unarmored photosynthetic dinoflagellate Cochlodinium fulvescens Iwataki, Kawami et Matsuoka sp. nov. were examined by light microscopy and molecular phylogenetic analyses based on partial large subunit ribosomal DNA (LSU rDNA) and small subunit ribosomal DNA (SSU rDNA) sequences. The cells of C. fulvescens closely resemble C. polykrikoides, one of the most harmful red tide forming dinoflagellates, due to it possessing a cingulum encircling the cell approximately twice, a spherical nucleus positioned in the anterior part of the cell and an eyespot‐like orange pigmented body located in the dorsal side of the epicone, as well as formation of cell‐chains. However, this species is clearly distinguished from C. polykrikoides based on several morphological characteristics, namely, cell size, shape of chloroplasts and the position of narrow sulcus situated in the cell surface. The sulcus of C. fulvescens is located at the intermediate position of the cingulum in the dorsal side, whereas that of C. polykrikoides is situated immediately beneath the cingulum. LSU rDNA phylogenies indicated that C. fulvescens is clearly distinct from, but closely related to C. polykrikoides among dinoflagellates.

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 et al. 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 ~14–18 °C and salinities of 22–34 psu.

Protoperidinium tricingulatum sp. nov. (Dinophyceae), a new motile form of a round, brown, and spiny dinoflagellate cyst

A small, broadly ovoidal and heterotrophic dinoflagellate containing round, brownish, and spiny cyst was found in the water column of Huibertsplaat in the Wadden Sea off the coast of the Netherlands. This dinoflagellate had these conspicuous morphological characters: a five‐sided first apical plate (1′), only three cingular plates, and an extremely small first antapical plate. Based on these morphological features, Protoperidinium tricingulatum Kawami, vanWezel, Koeman et Matsuoka is described as a new species. The flagellar pore of P. tricingulatum is covered with a small fin, which rises from the left side of the right sulcal plate to the large V‐shaped posterior sulcal plate. This feature suggests that P. tricingulatum is assigned to the Abés Monovela Group. The cyst stage of P. tricingulatum was positively linked to the vegetative stage by comparison of the ribosomal 5.8S rDNA, internal transcribed spacers (ITS1 and ITS2). Living cysts of P. tricingulatum are round, brownish, and covered with many slender spines bearing capitate or cauliforate distal ends. The cyst also possesses a theropylic archeopyle formed by a slit corresponding to parasutures between three apical and two apical intercaraly plates. These morphological characters indicate that this species is morphologically related to two dinoflagellate cyst‐genera Islandinium and Echinidinium.

Further examination of the cyst-theca relationship of Protoperidinium thulesense (Peridiniales, Dinophyceae) and the phylogenetic significance of round brown cysts

K. Matsuoka, H. Kawami, R. Fujii and M. Iwataki. 2006. Further examination of the cyst-theca relationship of Protoperidinium thulesense (Peridiniales, Dinophyceae) and the phylogenetic significance of round brown cysts. Phycologia 45: 632–641. DOI: 10.2216/05-42.1 The heterotrophic armored dinoflagellate Protoperidinium thulesense has an unusual combination of morphological characters, i.e. the thecal plate arrangement of the motile cell resembles a typical Protoperidinium, whereas the shape and archeopyle of the cyst are like the diplopsalids. We have re-examined the cyst-motile relationship of P. thulesense by cyst incubation and thecal plate analysis together with a molecular phylogenetic study based on small subunit (SSU) rDNA sequences. Five isolates of P. thulesense, including motile cells and cysts, and three Protoperidinium and three diplopsalid species were examined by using the single cell PCR method. The thecal plate arrangement of the motile cells isolated from field samples and those germinated from cysts were identical. The plate formula was: Po, X, 3′, 3a, 7″, 3c+t, 4s, 5′″, 2″″. The cysts of P. thulesense were round and brown with a theropylic archeopyle, and rather similar to the diplopsalid species, Diplopsalis lenticula, D. lebourae, Gotoius abei and others. SSU rDNA sequence analysis reveals P. thulesense is closely related to the subgenus Protoperidinium, especially species of the section Conica, and distant from the diplopsalid species. The phylogenetic and taxonomic significances of Protoperidinium and diplopsalid round brown cysts with a theropylic archeopyle are discussed.

The First Appearance of Toxic Dinoflagellate Alexandrium tamarense (Gonyaulacales, Dinophyceae) Responsible for the PSP Contaminations in Gamak Bay, Korea

In Gamak Bay, Paralytic Shellfish Poisoning (PSP) was first detected from seafoods in 2003, however the toxin source is unknown yet. In this study, we report potential PSP producers of toxic dinoflagellates, describing morphology and abundance of cysts isolated from surface sediment of Gamak Bay. The most abundant type in these cysts was characterized with ellipsoidal and transparent wall identical to Alexandrium catenella and/or A. tamarense. Germination experiment of the cysts revealed that all motile cells germinated were morphologically identified as A. tamarense. This result suggests that A. tamarense may relate to PSP contaminations in Gamak Bay. Moreover, bottom water temperature in Gamak Bay is favorable for germination of A. tamarense cysts. Further studies are required to carry out the PSP monitoring for preventing the risk of PSP events that may outbreak in future at Gamak Bay.

Cellular and body scale morphology of Heterocapsa huensis sp. nov. (Peridiniales, Dinophyceae) found in Hue, Vietnam

Cellular and body scale structure of a new armored dinoflagellate Heterocapsa huensis, collected from Hue, Vietnam were investigated. Morphology of motile cell was observed by light, fluorescent and scanning electron microscopy, and body scale structure was examined by whole mounts of transmission electron microscopy. Cells of H. huensis were ellipsoid with a spherical nucleus located in the posterior and multiple pyrenoids located above the nucleus; this arrangement was similar to that of Heterocapsa pygmaea. Transmission electron microscopy revealed ultrastructure of the body scales consisted of a rounded triangular basal plate and three‐dimensional ornaments. Structure of the basal plate resembles that of Heterocapsa illdefina; however, the number of the peripheral spine is different from that of H. illdefina and this structure has never been reported from Heterocapsa species. A new Heterocapsa species, H. huensis Iwataki et Matsuoka sp. nov., is described based on positions of organelles and body scale ultrastructure.