![]() | Madanidinium loirii gen. et sp nov. (Dinophyceae), a new marine benthic dinoflagellate from Martinique Island, Eastern Caribbean Auteur(s) : Chomerat, Nicolas Bilien, Gwenael Éditeur(s) : Taylor & Francis Ltd Résumé : A new benthic phototrophic dinoflagellate is described from sediments of a tropical marine cove at Martinique Island and its micromorphology is studied by means of light and electron microscopy. The cell contains small golden-brown chloroplasts and the oval nucleus is posterior. It is laterally compressed, almost circular in shape when viewed laterally. It consists of a small epitheca tilted toward the right lateral side and a larger hypotheca. In the left view, the cingulum is more anterior and the epitheca is reduced. The cingulum is displaced and left-handed. This organism is peculiar in having no apical pore and its thecal plate arrangement is 2 ' 1a 7 '' 5c 3s 5 ''' 1 ''''. The plates are smooth with small groups of pores scattered on their surface. An area with 60-80 densely arranged pores is found near the centre of the 2 ''' plate, on the left lateral side. Morphologically, these features are different from all other laterally compressed benthic genera. In addition, molecular genetic sequences of SSU and partial LSU form a distinct and well-supported clade among dinoflagellates and support the erection of a new genus. However, molecular phylogenies inferred from ribosomal genes failed to confirm any clear relationship with other benthic taxa and affinity with other laterally compressed dinoflagellates has not been demonstrated. Hence, the taxonomic affinity of Madanidinium loirii with a defined order and family is unclear at the moment. European Journal Of Phycology (0967-0262) (Taylor & Francis Ltd), 2014-04 , Vol. 49 , N. 2 , P. 165-178 Droits : 2014 British Phycological Society http://archimer.ifremer.fr/doc/00195/30622/29458.pdf DOI:10.1080/09670262.2014.898797 http://archimer.ifremer.fr/doc/00195/30622/ | Partager |
![]() | Morphology and molecular phylogeny of prorocentrum consutum sp. nov. (dinophyceae), a new benthic dinoflagellate from south Brittany (northwestern France) Auteur(s) : Chomerat, Nicolas Sellos, Daniel Y. Zentz, Frederic Nezan, Elisabeth Éditeur(s) : Wiley / Blackwell Résumé : A new marine benthic Prorocentrum species from sandy habitats of South Brittany (northwestern France), P. consutum sp. nov., is described using LM and SEM and molecular phylogenetic analyses. Cells have a subcircular to broadly ovoid shape and are plainly flattened. They are 57-61 lm long and 52-55 lm wide. A central pyrenoid is present, and the kidney-shaped nucleus is positioned in the posterior region. In right valve view, the periflagellar area is deeply excavated, and the left valve forms a prominent apical ridge. The periflagellar area consists of nine platelets, and a small narrow collar is present around the flagellar pore. The ornamentation of this new species is very peculiar and is characterized by a ring of round areolae located at the periphery of the valves, each areola containing three or four pores. Apart from this ring of areolae, the cell surface is smooth and with scattered pores. Pores are not present in the center of the right or left valve. The intercalary band is generally narrow and faintly striated horizontally. The molecular phylogenetic position of P. consutum sp. nov. was inferred using SSU and LSU rDNA. In both analyses, this species branched with high support in the clade comprising species with a symmetric shape and appeared to be a sister group to that formed by P. lima and other tropical benthic species, such as P. arenarium, P. belizeanum, P. hoffmannianum, and P. maculosum. Journal of Phycology (0022-3646) (Wiley / Blackwell), 2010-02 , Vol. 46 , N. 1 , P. 183-194 Droits : 2010 Wiley Blackwell Publishing, Inc. Phycological Society of America http://archimer.ifremer.fr/doc/2010/publication-7449.pdf DOI:10.1111/j.1529-8817.2009.00774.x http://archimer.ifremer.fr/doc/00000/7449/ | Partager Voir aussi Taxonomy SSU rDNA SEM Prorocentrum Nuclear DNA Molecular phylogeny LSU rDNA Dinoflagellates Télécharger |
![]() | Prorocentrum bimaculatum sp nov (Dinophyceae, prorocentrales), a new benthic dinoflagellate species from Kuwait (Arabian gulf) Auteur(s) : Chomerat, Nicolas Saburova, Maria Bilien, Gwenael Al-yamani, Faiza Éditeur(s) : Wiley-blackwell Résumé : A new benthic dinoflagellate species, Prorocentrum bimaculatum sp. nov., is studied from Kuwaits marine sediments, based on detailed morphological and molecular data. Cells are large, oblong oval in shape. They are 49.955.3 mu m long and 38.443.2 mu m wide. The ornamentation of this new species is peculiar, and characterized by smooth valves with large pores (0.320.50 mu m) scattered on their surface, except in two circular patches of similar to 15 mu m in diameter, devoid of ornamentation and located on both sides of the valve centers. The periflagellar area is widely triangular, located in a moderate excavation of the right valve, and comprises nine platelets. The intercalary band of P. bimaculatum is smooth. The molecular phylogenetic position of this new taxon was inferred from SSU and LSU rDNA genes. In both phylogenetic analyses, P. bimaculatum branched with high support with Prorocentrum consutum and formed a clade sister to the one including P. lima and related species such as P. arenarium, P. belizeanum, P. hoffmannianum, and P. maculosum. From the phylogenetic study, since most species related to P. bimaculatum are known for their toxic effects and production of okadaic acid, this new species can be considered as a potential toxin producer, but this has to be analyzed. Journal Of Phycology (0022-3646) (Wiley-blackwell), 2012-02 , Vol. 48 , N. 1 , P. 211-221 Droits : 2012 Phycological Society of America http://archimer.ifremer.fr/doc/00066/17756/15698.pdf DOI:10.1111/j.1529-8817.2011.01102.x http://archimer.ifremer.fr/doc/00066/17756/ | Partager Voir aussi Arabian Gulf benthic dinoflagellates Kuwait molecular phylogeny morphology nuclear DNA Prorocentrum rDNA SEM taxonomy Télécharger |
![]() | The Protist Ribosomal Reference database (PR2): a catalog of unicellular eukaryote Small Sub-Unit rRNA sequences with curated taxonomy Auteur(s) : Guillou, Laure Bachar, Dipankar Audic, S Bass, David Berney, Cedric Bittner, Lucie Boutte, Christophe Burgaud, Gaetan Éditeur(s) : Oxford Univ Press Résumé : The interrogation of genetic markers in environmental meta-barcoding studies is currently seriously hindered by the lack of taxonomically curated reference data sets for the targeted genes. The Protist Ribosomal Reference database (PR2, http://ssurrna. org/) provides a unique access to eukaryotic small sub-unit (SSU) ribosomal RNA and DNA sequences, with curated taxonomy. The database mainly consists of nuclear-encoded protistan sequences. However, metazoans, land plants, macrosporic fungi and eukaryotic organelles (mitochondrion, plastid and others) are also included because they are useful for the analysis of hightroughput sequencing data sets. Introns and putative chimeric sequences have been also carefully checked. Taxonomic assignation of sequences consists of eight unique taxonomic fields. In total, 136 866 sequences are nuclear encoded, 45 708 (36 501 mitochondrial and 9657 chloroplastic) are from organelles, the remaining being putative chimeric sequences. The website allows the users to download sequences from the entire and partial databases (including representative sequences after clustering at a given level of similarity). Different web tools also allow searches by sequence similarity. The presence of both rRNA and rDNA sequences, taking into account introns (crucial for eukaryotic sequences), a normalized eight terms ranked-taxonomy and updates of new GenBank releases were made possible by a long-term collaboration between experts in taxonomy and computer scientists. Nucleic Acids Research (0305-1048) (Oxford Univ Press), 2013-01 , Vol. 41 , N. D1 , P. D597-D604 Droits : The Author(s) 2012. Published by Oxford University Press. http://archimer.ifremer.fr/doc/00114/22492/20174.pdf DOI:10.1093/nar/gks1160 http://archimer.ifremer.fr/doc/00114/22492/ | Partager |