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  • 1
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    WALTER DE GRUYTER & CO
    In:  EPIC3Botanica Marina, WALTER DE GRUYTER & CO, 56(4), pp. 399-408, ISSN: 0006-8055
    Publication Date: 2019-07-17
    Description: Azadinium spinosum is a planktonic dinoflagellate, and a source of azaspiracids, a group of lipophilic toxins of human health concern. Little is known about the biology of this genus, and its phylogenetic position within the Dinophyceae is not yet fully resolved. Here, we present detailed observations regarding its vegetativecell division. As a first sign of cell division, the round interphase nucleus enlarges and becomes elongate in a slightly oblique orientation. The nucleus then divides along its longitudinal axis. Cytokinesis of A. spinosum occurs in motile cells and is of the desmoschisis type, i.e., the parental theca is shared between the two sister cells. Divided cells completely separate before the thecal plates are fully replaced. The anterosinistral daughter cell keeps the parent cell ’ s apex, including the apical pore complex and all the apical and epithecal intercalary plates, whereas the posterodextral daughter cell keeps, among others, both antapical plates. In general, the course of the fission line follows the plate overlap pattern and is, with a few exceptions, similar to other species of the Gonyaulacales. A literature survey shows that both desmoschisis and eleuteroschisis have been described for Gonyaulacales and Peridiniales, which suggests that mode of division may not be a good ordinal criterion for classification.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 2
    Publication Date: 2023-03-13
    Description: A recently published study analyzed the phylogenetic relationship between the genera Centrodinium and Alexandrium, confirming an earlier publication showing the genus Alexandrium as paraphyletic. This most recent manuscript retained the genus Alexandrium, introduced a new genus Episemicolon, resurrected two genera, Gessnerium and Protogonyaulax, and stated that: “The polyphyly [sic] of Alexandrium is solved with the split into four genera”. However, these reintroduced taxa were not based on monophyletic groups. Therefore this work, if accepted, would result in replacing a single paraphyletic taxon with several non-monophyletic ones. The morphological data presented for genus characterization also do not convincingly support taxa delimitations. The combination of weak molecular phylogenetics and the lack of diagnostic traits (i.e., autapomorphies) render the applicability of the concept of limited use. The proposal to split the genus Alexandrium on the basis of our current knowledge is rejected herein. The aim here is not to present an alternative analysis and revision, but to maintain Alexandrium. A better constructed and more phylogenetically accurate revision can and should wait until more complete evidence becomes available and there is a strong reason to revise the genus Alexandrium. The reasons are explained in detail by a review of the available molecular and morphological data for species of the genera Alexandrium and Centrodinium. In addition, cyst morphology and chemotaxonomy are discussed, and the need for integrative taxonomy is highlighted.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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  • 3
    Publication Date: 2023-03-13
    Description: Gonyaulacales include a considerable number of harmful algae and to understand their origin and rise, knowledge of the evolutionary relationships is necessary. Many scientific names of protists introduced prior to the availability of DNA analytics are ambiguous and impede communication about biological species and their traits in the microbial world. Strains of Lingulodinium polyedra were established from its type locality in the Kiel Fjord (Germany) to clarify its taxonomy. Moreover, the phylogeny of Gonyaulacales was inferred based on 329 rRNA sequence accessions compiled in a curated sequence data base, with as much as possible type material equivalents included. Gonyaulacales were monophyletic and segregated into seven lineages at high systematic level, of which †Lingulodiniaceae constituted the first branch of the Gonyaulacales. Their type species had a plate formula APC (Po, X, cp), 3′ , 3a, 6′ ′ 6c, 6s, 6′ ′ ′ , 2′ ′ ′ ′ and is taxonomically clarified by epitypification. Recommendations for this important taxonomic tool are provided, with a focus on microorganisms. Most gonyaulacalean taxa established at generic rank are monophyletic, with Alexandrium, Coolia and Gonyaulax as notable exceptions. From an evolutionary perspective, gonyaulacalean dinophytes with quinqueform hypotheca are monophyletic and derive from a paraphyletic group showing the sexiform configuration.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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