A New Marine Species of Amphidinium (Dinophyceae) from Thermaikos Gulf, Greece

Genus Amphidinium Claparède et Lachmann (Gymnodiniales, Dinophyceae) sensu lato has recently undergone a reappraisal using extended microscopical methods and genetic comparisons, with the type species and morphologically similar species used for the redescription of the genus Amphidinium sensu stricto. Within the latter concept of the genus, the new species Amphidinium thermaeum is established using light and scanning electron microscopy in combination with LSU rDNA phylogeny. This species was isolated from the Thermaikos Gulf in Greece, and its description is largely based on observations of cultured material. The main diacritic features distinguishing A. thermaeum from related taxa were: shape, size and plasticity of the cell, position of distal and proximal cingulum ends, site of longitudinal flagellar insertion, sulcal course, pusule details, plastid characteristics, and mode of cell division. Genetic phylogeny applying Bayesian Inference, Maximum Likelihood, and Neighbor-Joining analyses, places A. thermaeum in an independent position within the Amphidinium sensu stricto monophyletic group, and the new species is closely related to its small and morphologically similar siblings (A. massartii, A. klebsii, A. trulla, A. gibbosum, A. carterae)

Morfología y filogenia del rDNA de una subespecie mediterránea de Coolia Monotis (Dinophyceae) de Grecia

Sequences of LSU and SSU ribosomal RNA genes and phylogeny have not been widely investigated for the dinoflagellate Coolia monotis Meunier, and no information is available on the small and large rDNA subunits of Mediterranean strains. A strain isolated from the Thermaikos Gulf in northern Greece was identified as C. monotis—a new record for the Greek algal flora—using thecal morphology by light, epifluorescence and scanning electron microscopy. The small subunit and partial (D1/D2) large subunit sequences were analyzed and compared to other strains of C. monotis and dinoflagellates from various regions. Thecal architecture showed that the Greek strain of C. monotis was phenotypically similar, but not identical, to other strains reported in literature. The partial LSU sequence (700 bp) was found to vary by 113 bp positions (16%) from the C. monotis strain from New Zealand, whereas the SSU (1757 bp) had 15 bp differences (0.85%) from the strain from Norway. Phylogenetic tree construction showed that the Greek strain fell within the Coolia clade and had a close relationship with the families Ostreopsidaceae and Goniodomaceae of the order Gonyaulacales. Preliminary findings suggest the existence of different genotype strains of C. monotis with large intraspecific genetic variability and minimal morphological differentiation (similar phenotypes). Certain ecological and evolutionary implications of these findings are discussed.Las secuencias de los genes del RNA de las subunidades ribosomales grandes y pequeñas (LSU y SSU, respectivamente) y la filogenia del dinoflagelado Coolia monotis Meunier han sido poco investigadas, y no hay información disponible sobre los genes LSU y SSU de subespecies mediterráneas. Una subespecie aislada del golfo de Thermaikos en el norte de Grecia fue identificada como C. monotis –una nueva aportación a la flora algal griega– por medio de la morfología de la teca observada a través de microscopía óptica, de epifluorescia y electrónica. Las secuencias correspondientes a la subunidad pequeña y a la parte (D1/D2) de la subunidad grande fueron analizadas y comparadas a las de otras subespecies de C. monotis y otras especies de dinoflagelados de diversas regiones. La arquitectura de la teca mostró que la subespecie griega de C. monotis era fenotípicamente similar, pero no idéntica, a otras subespecies registradas en la literatura. Se encontró que la secuencia parcial de la LSU (700 pares de bases o bp) difería de la de C. monotis de Nueva Zelanda en las posiciones de 113 bp (16%), mientras que la SSU (1757 bp) se diferenciaba en 15 bp (0.85%) de la subespecie de Noruega. La construcción del árbol filogenetico demostró que la subespecie griega se situaba dentro de la rama de Coolia y presentaba una relación cercana con las familias Ostreopsidaceae y Goniodomaceae del orden Gonyaulacales. Resultados preliminares sugieren la existencia de diversos genotipos de la subespecie de C. monotis con una importante variabilidad genética intraespecífica y una mínima diferenciación morfológica (fenotipos similares). Se comentan diversas implicaciones ecológicas y evolutivas de estos resultados

Genetic Diversity, Morphological Uniformity and Polyketide Production in Dinoflagellates (Amphidinium, Dinoflagellata)

Dinoflagellates are an intriguing group of eukaryotes, showing many unusual morphological and genetic features. Some groups of dinoflagellates are morphologically highly uniform, despite indications of genetic diversity. The species Amphidinium carterae is abundant and cosmopolitan in marine environments, grows easily in culture, and has therefore been used as a ‘model’ dinoflagellate in research into dinoflagellate genetics, polyketide production and photosynthesis. We have investigated the diversity of ‘cryptic’ species of Amphidinium that are morphologically similar to A. carterae, including the very similar species Amphidinium massartii, based on light and electron microscopy, two nuclear gene regions (LSU rDNA and ITS rDNA) and one mitochondrial gene region (cytochrome b). We found that six genetically distinct cryptic species (clades) exist within the species A. massartii and four within A. carterae, and that these clades differ from one another in molecular sequences at levels comparable to other dinoflagellate species, genera or even families. Using primers based on an alignment of alveolate ketosynthase sequences, we isolated partial ketosynthase genes from several Amphidinium species. We compared these genes to known dinoflagellate ketosynthase genes and investigated the evolution and diversity of the strains of Amphidinium that produce them

A New Marine Species of Amphidinium (Dinophyceae) from Thermaikos Gulf, Greece

Genus Amphidinium Claparède et Lachmann (Gymnodiniales, Dinophyceae) sensu lato has recently undergone a reappraisal using extended microscopical methods and genetic comparisons, with the type species and morphologically similar species used for the redescription of the genus Amphidinium sensu stricto. Within the latter concept of the genus, the new species Amphidinium thermaeum is established using light and scanning electron microscopy in combination with LSU rDNA phylogeny. This species was isolated from the Thermaikos Gulf in Greece, and its description is largely based on observations of cultured material. The main diacritic features distinguishing A. thermaeum from related taxa were: shape, size and plasticity of the cell, position of distal and proximal cingulum ends, site of longitudinal flagellar insertion, sulcal course, pusule details, plastid characteristics, and mode of cell division. Genetic phylogeny applying Bayesian Inference, Maximum Likelihood, and Neighbor-Joining analyses, places A. thermaeum in an independent position within the Amphidinium sensu stricto monophyletic group, and the new species is closely related to its small and morphologically similar siblings (A. massartii, A. klebsii, A. trulla, A. gibbosum, A. carterae)