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The planktonic dinoflagellate Prorocentrum compressum is widespread in warm and temperate seas. A strain identified as P. cf. compressum BEA 0681B isolated from the island of Gran Canaria, NE Atlantic Ocean, showed a divergence in rDNA/ITS phylogenies with respect to P. compressum. The Canarian strain was oval, with an average length‐to‐width ratio of 1.35, smooth thecal surface with less than 150 thecal pores, including oblique pores, sometimes with a bifurcated opening. In contrast, P. compressum was rounder, with a length‐to‐width ratio < 1.2, with reticulate‐foveate ornamentation and 200–300 pores per valve. We propose Prorocentrum canariense sp. nov. These species clustered as the most early‐branching lineage in the clade Prorocentrum sensu stricto. Although this clade mainly contains planktonic species, the closer relatives were the benthic species P. tsawwassenense and P. elegans. Interestingly, P. compressum and P. canariense sp. nov. are widely distributed in temperate and warm seas without an apparent morphological adaptation to planktonic life. The formation of two concentric hyaline mucilaginous walls could contribute to this success. We discuss the use of Prorocentrum bidens to solve the nomenclature issue of P. compressum that was described citing a diatom as basionym. [ABSTRACT FROM AUTHOR]

Spiny‐surfaced species of Prorocentrum form harmful algal blooms, and its taxonomic identity is obscure due to the size and shape variability. Molecular phylogenies reveal two major clades: one for P. cordatum with sequences mainly retrieved as P. minimum, and the other for P. shikokuense with sequences also retrieved as P. dentatum and P. donghaiense. Several closely related clades still need to be characterized. Here, we provide nuclear SSU and LSU rRNA genes, and nuclear ITS region (ITS1‐5.8S gene‐ITS2) sequences of the strain CCMP3122 isolated from Florida (initially named P. donghaiense) and strains Prorocentrum sp. RCC6871–2 from the Ross Sea, Antarctica. We describe Prorocentrum thermophilum sp. nov. based on the strain CCMP3122, a species also distributed in the open waters of the Gulf of Mexico, New Zealand, and the Arabian Gulf; and Prorocentrum criophilum sp. nov. based on the strain RCC6872, which is distributed in the Antarctic Ocean and Arctic Sea. Prorocentrum thermophilum is roundish (~14 μm long, ~12 μm wide), with an inconspicuous anterior spine‐like prolongation under light microscopy, valves with tiny, short knobs (5–7 per μm2), and several (<7) large trichocyst pores (~0.3 μm) in the right valve, as well as smaller pores (~0.15 μm). Prorocentrum criophilum is round in valve view (~11 μm long, 10 μm wide) and asymmetrically roundish in lateral view, the periflagellar area was not discernible under light microscopy, valves with very tiny, short knobs (6–10 per μm2), and at least 12 large pores in the right valve. Other potentially undescribed species of spiny‐surfaced Prorocentrum are discussed. [ABSTRACT FROM AUTHOR]

The Gonyaulacales includes some of the most intensely investigated genera of harmful dinoflagellates. The knowledge of the evolutionary relationships is necessary, but incomplete because genera such as Schuettiella have not been studied by contemporary methods. The morphology and molecular phylogeny of type species of the genus Schuettiella, S. mitra, have been investigated from Brazil. The first scanning electron micrographs reveal a distinctive thecal ornamentation with sunken stripes and rows with exclamation mark‐shaped pores in the postcingular plates. The Kofoidean plate formula Po, 2′, 1a, 6″ is re‐interpreted as Po, 3′, 1a, 5″, after considering the narrow mid‐ventral plate as homologous to the first apical plate, although it does not reach the apex. In the rRNA gene phylogenies, the sequences of S. mitra clustered as an independent lineage closely related to the globular and planktonic Protoceratiaceae (Ceratocorys, Pentaplacodinium, Protoceratium) and the laterally compressed benthic genus Carinadinium (formerly Thecadinium). Schuettiella and Carinadinium are considered members of the Protoceratiaceae. The possession of a single anterior intercalary plate is an apomorphic trait of this family. This reinforces the value of the number of intercalary plates as a diagnostic character for the classification of the gonyaulacalean families despite the differences in the general appearance. [ABSTRACT FROM AUTHOR]

Gymnodinium gracile, described from the coasts of Denmark in 1881, is one of the first described unarmored dinoflagellates. Individuals that morphologically fit with the original description were isolated from the English Channel (North‐East Atlantic). The SSU rRNA gene sequences were identical to the sequences identified as Balechina pachydermata and Gymnodinium amphora from the Mediterranean Sea and Brazil. We propose the transfer of Gymnodinium gracile into the genus Balechina as B. gracilis comb. nov. These sequences constitute an independent lineage, clustering with numerous environmental sequences from polar to tropical waters. The widespread distribution, the high plasticity in size, shape and coloration and the difficulties in discerning the fine longitudinal striae have contributed to the description of numerous synonyms: Amphidinium vasculum, Balechina pachydermata (=Gymnodinium pachydermatum), Gymnodinium achromaticum, G. abbreviatum, G. amphora, G. dogielii, G. lohmannii (=G. roseum sensu Lohmann 1908), G. situla, and Gyrodinium cuneatum (=G. gracile sensu Pouchet 1885). [ABSTRACT FROM AUTHOR]

The molecular phylogeny of the sand-dwelling dinoflagellate Planodinium striatum was investigated from isolates collected in the NE English Channel. In the SSU rRNA gene phylogeny, the sequences of Planodinium clustered with the type species of Plagiodinium, P. belizeanum, and more distantly related to Plagiodinium ballux. Although the SSU rRNA gene sequences of Planodinium showed a high percentage of identity (96%) with partial sequences of species of Podolampas (~1200 base pairs), the SSU rRNA gene phylogenies did not show a relationship with the clade of the Podolampadaceae (Podolampas, Blepharocysta, Roscoffia), neither with the sequences of the sanddwelling genus Cabra. The SSU rRNA gene sequences of Plagiodinium belizeanum and P. ballux showed a low percentage of identity (96%) clustering in separate clades in the SSU rRNA gene phylogeny with Planodinium. The morphology of P. ballux and its generic type differed in the plate arrangement and the morphology of the cingulum, amongst other features. Based on the morphological and molecular differences, we propose the new genus Chrysodinium gen. nov. for P. ballux, with the re-interpreted thecal plate formula Po 3' 1'' 7c 2s 5''' 1''''. [ABSTRACT FROM AUTHOR]

Climacodium frauenfeldianum is a planktonic chain-forming diatom able to proliferate in severely oligotrophic waters of tropical seas. In this study, a strain of C. frauenfeldianum, the type of Climacodium, was established in culture from the tropical southwestern Atlantic Ocean off Brazil. SEM observations showed weakly silicified cells, without visible surface sculpturing. In the small subunit (SSU) rRNA and ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit (rbcL) gene phylogeny, C. frauenfeldianum clustered with sequences of Bellerochea malleus (the type of Bellerochea) and B. horologicalis. Contrary to previous classifications that placed Climacodium in the Hemiaulaceae, Climacodium and Bellerochea should be placed in the same family, Bellerocheaceae. The species Bellerochea yucatanensis needs further research because sequences of the single strain available clustered with the genus Lithodesmioides. In adaptation to the oligotrophic open ocean environment, C. frauenfeldianum seems to have evolved an appearance closer to Hemiaulus, i.e. very lightly silicified flat cells with long elevations, and with diazotrophic cyanobionts. [ABSTRACT FROM AUTHOR]

Some diatoms are able to colonize as epibionts on their potential zooplankton predators. Here, we report Pseudohimantidium pacificum living on the copepod Corycaeus giesbrechti and as a new finding on Oithona nana, Protoraphis atlantica living on the copepod Pontellopsis brevis, Protoraphis hustedtiana on the cypris larvae of barnacles, and Falcula hyalina on the copepod Acartia lilljeborgii. The epizoic diatoms were able to grow as free‐living forms under culture conditions. Pseudohimantidium pacificum and P. atlantica appeared as the most derived species from their benthic diatom ancestors. The mucilage pad or stalk of the strains of these species showed important morphological distinction when compared with their epizoic forms. Barnacle larvae explore benthic habitats before settlement, and epibiosis on them is an example where P. hustedtiana profits from the host behavior for dispersal of its benthic populations. Molecular phylogenies based on the SSU rRNA and RuBisCO large subunit (rbcL) gene sequences revealed F. hyalina as an independent lineage within the Fragilariales (Tabularia, Catacombas, and others), consistent with its morphological distinction in the low number of rows (≤6) in the ocellulimbus, among other features. We propose the transfer of F. hyalina to the genus Pseudofalcula gen. nov. Molecular phylogeny suggests a single order for the members of the Cyclophorales and the Protoraphidales, and that the epibioses of araphid diatoms on marine zooplankton have been independently acquired several times. These clades are constituted of both epizoic and epiphytic/epilithic forms that evidence a recent acquisition of the epizoic modus vivendi. [ABSTRACT FROM AUTHOR]

Consortia of the peritrich ciliate Vorticella oceanica and the planktonic diatom Chaetoceros coarctactus are reported from the South Atlantic Ocean. The morphologies of the constituent species were similar to their counterparts from other geographical regions, revealing a widespread distribution in tropical waters. Besides, we describe Pseudovorticella coscinodisci sp. nov. that lives on Coscinodiscus wailesii and other pelagic diatoms off Brazil. The zooids were 34–45 μm long, and 19–30 μm wide with a stalk too short to coil. The cell surface showed a reticulate pellicle with 18–19 and 11–12 rows above and below the aboral ciliary wreath, respectively. In the SSU rDNA phylogeny V. oceanica clustered between the clades of Vorticella and Pseudovorticella/Epicarchesium , and Pseudovorticella coscinodisci sp. nov. clustered as a sister group of Pseudovorticella paracratera and P. sinensis . The V. oceanica-C. coarctactus consortium likely represents an obligate species-specific mutualistic symbiosis as the constituents are not known as free-living forms. In contrast, the diatom hosts are known as free-living forms in the consortia of Pseudovorticella coscinodisci . The new molecular data and species description will be valuable dataset for future research on the diversity and ecological significance of ciliate-diatom epibiotic consortia. [ABSTRACT FROM AUTHOR]

Prorocentrum mexicanum and P. rhathymum are toxicologically important dinoflagellates, but their relationship is not well defined. We investigated strains from Puerto Rico and Brazil by light and scanning electron microscopies. We provide molecular data from a strain isolated near the type locality of P. rhathymum, and the first morphological and molecular data from the South Atlantic Ocean. The rRNA gene ( rDNA) sequences of the Puerto Rican and Brazilian strains were identical, and their morphologies fit the description of P. rhathymum. In the molecular phylogenies, the globally distributed populations under the names P. mexicanum and P. rhathymum are intermixed and branched together, except for several divergent strains from Florida and Cuba. We examined the original descriptions and iconotypes of the species Prorocentrum maximum, P. brochii, P. mexicanum, and P. rhathymum. We conclude that P. maximum sensu Schiller's figure 41a corresponds to the earlier description of this species; the split of P. mexicanum and P. rhathymum was based on a misidentification because P. mexicanum sensu Cortés-Altamirano & Sierra-Beltrán corresponds to P. texanum var. cuspidatum; and P. rhathymum is a junior synonym of P. mexicanum. Several Floridian and Cuban strains correspond to a new species, which we describe as Prorocentrum steidingerae sp. nov. [ABSTRACT FROM AUTHOR]

The dinoflagellate genera Oxytoxum and Corythodinium that account for more than fifty species are widespread in warm oceans. These genera have been considered synonyms and thecal plate designations varied among authors. Several planktonic and sand-dwelling genera have been placed within the Oxytoxaceae. We obtained the first molecular data based on small subunit (SSU) rRNA gene sequences of Oxytoxum and Corythodinium, including the type species (O. scolopax and C. tessellatum) and C. frenguellii and C. cristatum. The three species of Corythodinium branched together a strong support [bootstrap (BP) of 98%]. This formed a sister clade with moderate support (BP 75%) with O. scolopax that supported the generic split. Oxytoxaceae should exclusively remain for Oxytoxum and Corythodinium, as an independent group, unrelated to any other known dinoflagellate. Oxytoxum was characterized by spindle-shaped cells with an anterior narrow epitheca, an apical spine and little cingular displacement. Corythodinium exhibits relatively broad cell shapes, with wider epitheca and greater cingular displacement, and an obovate or pentangular anterior sulcal plate that noticeably indented the epitheca. This suggested the need of new combinations for species that were described as Oxytoxum and possessed the characteristics of Corythodinium. [ABSTRACT FROM AUTHOR]

SUMMARY The dinoflagellate genus Coolia, which contains potentially toxic species, is an important component of epiphytic assemblages in marine ecosystems. The morphology of C. malayensis has been illustrated from strains isolated in Asia and Oceania. In this study, strains of C. malayensis isolated from the Caribbean Sea in Puerto Rico, and for the first time from the South Atlantic Ocean in Brazil, were investigated by light, epifluorescence and scanning electron microscopies. No significant morphological differences between these new strains and other geographically distant strains of C. malayensis were observed. In the LSU r DNA phylogeny, the C. malayensis sequences from Brazil and Puerto Rico branched within the clade of strains from Oceania and Asia. The recently described species C. santacroce branched as a sister group of C. monotis, and C. palmyrensis was basal to the combined group of C. monotis/C. malayensis/C. santacroce. A tentative undescribed species from Florida and New Zealand branched as a sister group of C. malayensis. Our results confirm that C. malayensis showed a cosmopolitan distribution in tropical to subtropical waters, while the type species C. monotis remains endemic for the Mediterranean Sea and the temperate North Atlantic. [ABSTRACT FROM AUTHOR]

We investigated the morphology and evolutionary relationships ofTorodiniumspp. andKatodinium glaucum, unarmoured dinoflagellates characterized by a small hyposome. An emended generic description ofTorodiniumwas proposed based on light and scanning electron microscopy.Torodiniumexhibited a unique combination of morphological features including a minute hyposome, a long episome with longitudinal ribs and a canal of unknown function on the dextro-lateral side. Unlike any known dinoflagellate both cingulum and sulcus extended in the episome. The apex surface showed ribs that converged in a bill-like projection. The shape of the apical groove was a circular spiral that extended around the apex running in 2.5 turns in an anticlockwise direction. The type speciesT. teredowas usually longer thanT. robustum. The longitudinal outline ofT. teredowas linear, with almost parallel margins, a circular transversal section, a relatively large hyposome and a conspicuous bill-like projection. The longitudinal outline ofT. robustumwas oblong, widened in the middle, with an ellipsoidal transversal section, a small hyposome and a less prominent bill-like projection. Several morphological features ofKatodinium glaucum(=Gyrodinium glaucum) resembledGyrodinium, such as the cingular displacement, longitudinal ribs, trichocysts, rod-shaped and refractile bodies and a capsule that surrounded the spherical nucleus. Distinctive features ofK. glaucumwere the horseshoe-shaped apical groove under a tongue-shaped notch pointed towards the dorsal side, and a bifurcated proximal end of the cingulum. Phylogenetic analysis revealed thatTorodiniumspp. andK. glaucumformed two independent lineages with no close relationships with other known dinoflagellates. The morphology ofK. glaucumwas distant from the type species ofKatodinium. We propose the new genus and combinationLebouridinium glaucumgen. nov., comb. nov. for the speciesKatodinium glaucum. [ABSTRACT FROM PUBLISHER]

The genus Balechina (=subgenus Pachydinium) was established for heterotrophic gymnodinioid dinoflagellates with a thick cell covering. The type species, B. pachydermata (=Gymnodinium pachydermatum), showed numerous fine longitudinal striae, whereas B. coerulea (=G. coeruleum) showed ~24 prominent longitudinal surface ridges or furrows and a distinctive blue pigmentation. We have investigated the morphology and molecular phylogeny of these taxa and the species Gymnodinium cucumis, G. lira and G. amphora from the western Mediterranean, Brazil and Japan. Sudden contractions at the cingulum level were seen in B. pachydermata, which also showed a high morphological variability which included morphotypes that have been described as Amphidinium vasculum, G. amphora, G. dogielii and G. gracile sensu Kofoid and Swezy. Molecular phylogeny based on small subunit rRNA gene sequences revealed that Balechina coerulea, G. cucumis and G. lira formed a clade distantly related to the clade of the type species, B. pachydermata, and G. amphora. We propose the new genus Cucumeridinium for the species with longitudinal ridges and a circular apical groove (Cucumeridinium coeruleum comb. nov., C. lira comb. nov. and C. cucumis comb. nov.), and Gymnodinium canus and G. costatum are considered synonyms of C. coeruleum. The genus Balechina remains for the species with a double-layer cell covering, bossed surface with fine striae, and an elongated elliptical apical groove. At present, the genus is monotypic containing only B. pachydermata. [ABSTRACT FROM AUTHOR]

The speciesAmphidinium eludens, as described by Herdman (1922;Proc. Trans. Liverpool Biol. Soc.36: 18) based on her drawing in fig. 1, has been investigated for the first time by scanning electron microscopy and phylogenetic analysis. The morphological and molecular data reveal that this species is distantly related to other known dinoflagellates. Balech [1956,Rev. Algol., n. ser. 2(1–2): 30] citedAmphidinium eludensHerdman (1922, fig. 1) as the basionym of the type ofAdenoides, while he described and illustratedAmphidinium kofoidiiHerdman (1922, fig. 2) asAdenoides eludens. As the nomenclatural rules do not allow the change of basionym, we have re-defined the genusAdenoidesbased on the characteristics ofAmphidinium eludensHerdman (1922, fig. 1). The thecal plate formula ofAdenoides eludensis Po, 5′, 6″, 0c, 3+s, 5′″, 3p, 1″″. This species lacks a cingulum. The apical pore complex resembles that of peridinioid dinoflagellates, while the absence of a cingular groove is reminiscent of desmokont prorocentroids. We also proposePseudadenoides kofoidiigen. & comb. nov. based on Herdman’s 1922 fig. 2 ofAmphidinium kofoidiiwhich was described by Balech in 1956 and re-namedAdenoides eludens. [ABSTRACT FROM AUTHOR]

The dinoflagellate genus Chytriodinium, an ectoparasite of copepod eggs, is reported for the first time in the North and South Atlantic Oceans. We provide the first large subunit rDNA (LSU rDNA) and Internal Transcribed Spacer 1 (ITS1) sequences, which were identical in both hemispheres for the Atlantic Chytriodinium sp. The first complete small subunit ribosomal DNA (SSU rDNA) of the Atlantic Chytriodinium sp. suggests that the specimens belong to an undescribed species. This is the first evidence of the split of the Gymnodinium clade: one for the parasitic forms of Chytriodiniaceae ( Chytriodinium, Dissodinium), and other clade for the free-living species. [ABSTRACT FROM AUTHOR]

Dinoflagellates (Alveolata, Dinophyceae) are protists with a truly remarkable diversity in lifestyles (free-living, parasites and mutualistic symbionts), habitats (marine, freshwater, plankton, benthos), and trophic modes (heterotrophic, plastid-containing). Here Dinoflagellates are used to evaluate biases in the availability of molecular markers in relation to the variety of functional and ecological characteristics of protists. A large number of dinoflagellate sequences are available in GenBank, at least one for 56% of the 264 described genera. The most common marker is the small ribosomal subunit ribosomal DNA (49%). At the species level, SSU rDNA or the large subunit rDNA are available for 15% of the 2,386 described species. Availability of sequences of the internal transcribed spacers (ITS) and cytochrome oxidase I (COI) show a strong bias towards cultivable species. Relative to trophic mode, while about half of the known Dinoflagellates are heterotrophic, only 12% of them have been sequenced compared to 29% of the plastid-containing species. For the COI marker availability is 10 times greater for plastid-containing compared to heterotrophic species. Freshwater species are underrepresented (13%) relative to the marine forms (22%). A high proportion of benthic species have been sequenced (46%) reflecting interest in Symbiodinium and harmful epiphytic taxa. Most of the relatively few described mutualistic species have been sequenced (> 80%). In contrast, only 17% of the described parasitic species have been sequenced, and most of the available sequences were not identified at the species level. In recent years, new species have been described mostly from coastal blooms or cultures. These studies are favored by the availability of abundant material for detailed studies of ultrastructure and multi-gene molecular phylogenies. Many methods are difficult to apply for the scarce specimens available from the open ocean. The requirement of these protocols, easy to apply with cultured species, is an obstacle in our knowledge of the open ocean diversity because it discourages studies based on sparse material. Consequently, in recent years descriptions of new species from the open ocean have declined considerably. [ABSTRACT FROM AUTHOR]

We investigated the phylogeny of tintinnids (Ciliophora, Tintinnida) with 62 new SSU-rDNA sequences from single cells of 32 marine and freshwater species in 20 genera, including the first SSU-rDNA sequences for Amphorides, Climacocylis, Codonaria, Cyttarocylis, Parundella, Petalotricha, Undella and Xystonella, and 23 ITS sequences of 17 species in 15 genera. SSU-rDNA phylogenies suggested a basal position for Eutintinnus, distant to other Tintinnidae. We propose Eutintinnidae fam. nov. for this divergent genus, keeping the family Tintinnidae for Amphorellopsis, Amphorides and Steenstrupiella. Tintinnopsis species branched in at least two separate groups and, unexpectedly, Climacocylis branched among Tintinnopsis sensu stricto species. Tintinnopsis does not belong to the family Codonellidae, which is restricted to Codonella, Codonaria, and also Dictyocysta (formerly in the family Dictyocystidae). The oceanic genus Undella branched close to an undescribed freshwater species. Metacylis, Rhabdonella and Cyttarocylis formed a well supported clade with several Tintinnopsis species at a basal position. Petalotricha ampulla and Cyttarocylis cassis SSU-rDNA and ITS sequences were identical or almost identical. Therefore, we propose Cyttarocylis ampulla comb. nov. for them. Intensive use of single-cell isolation and sequencing revealed unexpected complexity in the evolutionary history of these relatively well-studied ciliates. Notably, the diversity of freshwater forms suggests multiple marine-freshwater invasions. [ABSTRACT FROM AUTHOR]

The dinoflagellate genus Heterodinium has unusual morphological characters such as a mid-ventral intercalary plate with a pore, a small plate in the left side of the dorsal epitheca, three antapical plates, and a well-developed anterior cingular list. We obtained the first SSU rDNA sequences from single cells of six species of Heterodinium from Mediterranean coastal and open waters. They included the type species H. scrippsii and H. rigdeniae and representatives of the other subgenera, Sphaerodinium (H. doma, H. milneri, H. globosum) and Platydinium (H. pavillardii). SSU rDNA phylogeny showed that Heterodinium spp. formed a well-supported monophyletic group (100% bootstrap support) composed of two subclades: one comprising H. doma, H. pavillardii, H. globosum and H. rigdeniae, and another comprising H. milneri and H. scrippsii. This whole heterodiniacean clade branched among the poorly resolved short-branching sequences of the lineage comprising groups of Gymnodiniales, Peridiniales, Dinophysales and Prorocentrales. The current classification into subgenera, and even into morphological groups, is not supported by the molecular data. In contrast to previous classifications, our SSU rDNA phylogeny suggests that the genus Heterodinium is divergent from the clade of Gonyaulacales. Accordingly, the supposed homology of pores and plate patterns of Heterodinium and gonyaulacoids may require revision. In Heterodinium, the first antapical and postcingular plates may be interpreted as sulcal plates, suggesting a more typical hypothecal tabulation (5′′′, 2′′′′). Our new data and analysis indicate that the systematic position of Heterodinium is uncertain at present. [ABSTRACT FROM PUBLISHER]

The dinophysoid dinoflagellates are currently divided into three families: Amphisoleniaceae, Dinophysaceae (mainly Dinophysis Ehrenb. and Phalacroma F. Stein), and Oxyphysaceae, the latter including only one member, Oxyphysis oxytoxoides Kof. Phalacroma has been recently reinstated separately from Dinophysis, and its amended description is currently restricted to cells whose epithecae were large but <1/4 of the cell length. With the aim of improving the phylogeny of Dinophysales, we obtained 54 new SSU rRNA gene sequences of 28 species. Taxon-rich SSU rDNA phylogenetic analysis showed that Dinophysales split into two major clades, one containing the Amphisoleniaceae ( Amphisolenia F. Stein- Triposolenia Kof.) and the other containing the Dinophysaceae. The latter are divided into two well-supported sister groups, the Dinophysaceae sensu stricto (s.s.) ( Dinophysis, Ornithocercus F. Stein, Histioneis F. Stein) and, tentatively, a separate family for the clade of the type and most of the Phalacroma species . Based on combined phylogenies of new SSU rDNA and available LSU rDNA data, O. oxytoxoides (elongated epitheca, >1/4 of the cell length) branched with a strong support with the type of Phalacroma. We therefore propose Phalacroma oxytoxoides comb. nov. for O. oxytoxoides. Our SSU rDNA phylogeny also suggests that the assumed high intraspecific variability of Dinophysis hastata F. Stein hides a number of cryptic species. According to their distinct phylogenetic placement, the forms D. hastata f. phalacromides Jørg. and D. hastata f. uracanthides Jørg. should be erected at the species level. We propose for them the names Dinophysis phalacromoides comb. nov. and Dinophysis uracanthoides comb. nov. [ABSTRACT FROM AUTHOR]

The order Noctilucales or class Noctiluciphyceae encompasses three families of aberrant dinoflagellates (Noctilucaceae, Leptodiscaceae and Kofoidiniaceae) that, at least in some life stages, lack typical dinoflagellate characters such as the ribbon-like transversal flagellum or condensed chromosomes. Noctiluca scintillans, the first dinoflagellate to be described, has been intensively investigated. However, its phylogenetic position based on the small subunit ribosomal DNA (SSU rDNA) sequence is unstable and controversial. Noctiluca has been placed either as an early diverging lineage that diverged after Oxyrrhis and before the dinokaryotes -core dinoflagellates- or as a recent lineage branching from unarmoured dinoflagellates in the order Gymnodiniales. So far, the lack of other noctilucoid sequences has hampered the elucidation of their phylogenetic relationships to other dinoflagellates. Furthermore, even the monophyly of the noctilucoids remained uncertain. We have determined SSU rRNA gene sequences for Kofoidiniaceae, those of the type Spatulodinium (=Gymnodinium) pseudonoctiluca and another Spatulodinium species, as well as of two species of Kofoidinium, and the first gene sequence of Leptodiscaceae, that of Abedinium (=Leptophyllus) dasypus. These taxa were collected from their type localities, the English Channel and the NW Mediterranean Sea, respectively. Phylogenetic analyses place the Noctilucales as a monophyletic group at a basal position close to parasites of the Marine Alveolate Group I (MAGI) and the Syndiniales (MAGII), before the core of dinokaryotic dinoflagellates, although with moderate support. [Copyright &y& Elsevier]

In contrast to the typical peridinioid dinoflagellates, the podolampadaceans are characterised by the absence of both a cingulum and a depressed sulcus. Until now, gene sequences for typical core podolampadaceans were not available. Despite this, two genera that appeared related in small subunit rRNA gene (SSU rDNA) trees, the sand-dwelling Roscoffia and Lessardia, which was previously considered an unarmoured taxon, were ascribed to this group since they showed coincidences in the plate formula with the podolampadaceans. However, the classification of Lessardia and Roscoffia as podolampadaceans remains controversial. To test whether these two genera are actually podolampadaceans, we obtained the first SSU rDNA sequences of four species of Podolampas (the type P. bipes, and P. elegans, P. palmipes and P. spinifera) and a Blepharocysta species, morphologically similar to the type B. splendor-maris, from the type locality, western Mediterranean Sea. SSU rDNA phylogenies showed that podolampadaceans and Roscoffia formed a well-supported monophyletic group composed of two subclades: one for Roscoffia and Blepharocysta and one other for Podolampas species. The whole podolampadacean clade branched in the lineage comprising Gymnodiniales, Peridiniales and Prorocentrales. By applying different methods and taxon sampling, we obtained alternative obtained alternative branching topologies. Either the podolampadaceans branched with low statistical support with Heterocapsa, Scrippsiella and Peridinium, while Lessardia branched relatively far with other peridinioids, or Lessardia branched as sister clade of the podolampadaceans with moderate support. The position of Lessardia appeared to be very instable, largely depending on the taxonomic sampling used. Although members of the Diplopsalis group have been suggested as ancestors of the podolampadaceans, our SSU rDNA phylogenies did not support a close relationship between both clades. [ABSTRACT FROM AUTHOR]

The dinoflagellate genus Ceratium contains marine and freshwater species. Freshwater species possess six cingular plates, thick plates in the concave ventral area and usually develop a third hypothecal horn. The marine Ceratium species (>62 species) possess five cingular plates and thin plates in the concave ventral area; a third hypothecal horn is atypical. Resting cysts, a common feature in the freshwater species, are unreported in marine species. We illustrate for the first time resting cysts in marine Ceratium species (C. furca and C. candelabrum). We obtained small subunit ribosomal RNA gene (SSU rDNA) sequences of 23 Ceratium species (more than one third of the total marine species described so far), with representatives of the four acknowledged subgenera. Phylogenetic analyses including the type species, the freshwater C. hirundinella, showed that the four available sequences of freshwater species formed a strongly supported subclade, very distant from the marine cluster. Our data support the splitting of Ceratium sensu lato into two genera. Ceratium sensu stricto should be reserved for freshwater species possessing six cingular plates (three cingular plates in dorsal view). The new genus name, Neoceratium gen. nov. should be applied to the marine species of Ceratium sensu lato that possess five cingular plates (two cingular plates in dorsal view). [Copyright &y& Elsevier]

Abstract: The dinoflagellates Chytriodinium affine, C. roseum and Dissodinium pseudolunula are ectoparasites of crustacean eggs. Here, we present new observations regarding their life cycle based on coastal plankton samples and incubations and analyze their molecular phylogeny using the small subunit ribosomal RNA gene (SSU rDNA) as a marker. In contrast to the typical stages already documented for its life cycle, we observed that D. pseudolunula dinospores may exceptionally differentiate inside a globular cyst. Despite its parasitic life style, the cysts and dinospores of D. pseudolunula contain chlorophyll a. We obtained the first SSU rDNA sequences for the genera Chytriodinium (the type C. roseum and C. affine) and Dissodinium (D. pseudolunula). Classical taxonomical schemes have ascribed these genera to the order Blastodiniales. However, our SSU rDNA-based phylogenetic analysis shows that these ectoparasites form a clade in the Gymnodinium sensu stricto group, unarmored dinokaryotic dinoflagellates of the order Gymnodiniales. They branch in a subgroup composed of warnowiids, polykrikoids, the type of Gymnodinium, G. fuscum and G. aureolum. Although Chytriodinium and Dissodinium appear to be relatives based on SSU rDNA phylogeny, feeding and host specificity, their life cycles are substantially different. Based on these data we consider that the type of life cycle is a poor criterion for classification at the family level. We suggest that the morphology of the infective cell is probably the most reliable phenotypic characteristic to determine the systematic position of parasitic dinoflagellates. [Copyright &y& Elsevier]

Members of the family Warnowiaceae are unarmored phagotrophic dinoflagellates that possess an ocelloid. The genus Erythropsidinium (= Erythropsis) has also developed a unique dynamic appendage, the piston, which is able to independently retract and extend for at least 2 min after the cell lyses. We provide the first small subunit ribosomal RNA gene sequences of warnowiid dinoflagellates, those of the type Erythropsidinium agile and one species of Warnowia. Phylogenetic analyses show that warnowiid dinoflagellates branch within the Gymnodinium sensu stricto group, forming a cluster separated from the Polykrikos clade and with autotrophic Pheopolykrikos beauchampii as closest relative. This reinforces their classification as unarmored dinoflagellates based on the shape of the apical groove, despite the strong ecological and ultrastructural diversity of the Gymnodinium s.s. group. Other structures, such as the ocelloid and piston, have no systematic value above the genus level. [ABSTRACT FROM AUTHOR]

ABSTRACT Dinophysoid dinoflagellates are usually considered a large monophyletic group. Large subunit and small subunit ( SSU) rDNA phylogenies suggest a basal position for Amphisoleniaceae ( Amphisolenia, Triposolenia) with respect to two sister groups, one containing most Phalacroma species plus Oxyphysis and the other Dinophysis, Ornithocercus, Dinophysoid dinoflagellates are usually considered a large monophyletic group. Large subunit and small subunit ( SSU) rDNA phylogenies suggest a basal position for Amphisoleniaceae ( Amphisolenia, Triposolenia) with respect to two sister groups, one containing most Phalacroma species plus Oxyphysis and the other Dinophysis, Ornithocercus, Histioneis, Citharistes and some Phalacroma species. We provide here new SSU rDNA sequences of Pseudophalacroma (pelagic) and Sinophysis (the only benthic dinophysoid genus). Molecular phylogenies support that they are very divergent with respect to the main clade of Dinophysales. Additional molecular markers of these two key genera are needed to elucidate the evolutionary relations among the dinophysoid dinoflagellates. Histioneis, Citharistes and some Phalacroma species. We provide here new SSU rDNA sequences of Pseudophalacroma (pelagic) and Sinophysis (the only benthic dinophysoid genus). Molecular phylogenies support that they are very divergent with respect to the main clade of Dinophysales. Additional molecular markers of these two key genera are needed to elucidate the evolutionary relations among the dinophysoid dinoflagellates. [ABSTRACT FROM AUTHOR]

• The parasite Syltodinium listii is first reported since the original description. • Syltodinium undulans comb. nov. is proposed for Gyrodinium undulans. • Syltodinium SSU rRNA gene sequence clusters with Chytriodinium and Dissodinium. • Chytriodiniaceae contain free-living taxa (G. aureolum , G. corollarium , G. plasticum). The parasitic dinoflagellate Syltodinium listii was investigated from the open waters of the English Channel, southern North Sea and the NW Mediterranean Sea. Syltodinium listii has been unreported since its original description in the North Sea. Cells of S. listii were able to infect copepod eggs of different species, and even nauplii, and after each infection formed up to 32 cells embedded in a mucous envelope. Infection of the same host by more than one dinoflagellate was frequent; although overall, the progeny were reduced in number. Molecular phylogeny based on the small subunit ribosomal RNA (SSU rRNA) gene revealed that S. listii clusters with a group of environmental sequences from the cold North Atlantic region as a sister group of Gymnodinium aureolum. The large subunit ribosomal RNA (LSU rRNA) gene sequences of S. listii from the English Channel and cf. Gyrodinium undulans from the Mediterranean Sea were identical. Thus, we propose Syltodinium undulans comb. nov. for Gyrodinium undulans. The first internal transcribed spacer (ITS) and complete SSU rRNA gene sequences of Dissodinium pseudolunula are provided. The parasitic species of Chytriodinium , Dissodinium and Syltodinium cluster together within the family Chytriodiniaceae, including the free-living species Gymnodinium aureolum , G. corollarium and G. plasticum. [ABSTRACT FROM AUTHOR]