A review of rare, poorly known, and morphologically problematic extant marine organic-walled dinoflagellate cyst taxa of the orders Gymnodiniales and Peridiniales from the Northern Hemisphere

Abstract

Dinoflagellates are a major component of the modern plankton. Of the 2192 species of marine free-living dinoflagellates presently described, an increasing number are being shown to produce resting cysts (probably hypnozygotes) within their life cycle. With rare exception, only the resting cysts fossilize, so they are of central importance in tracing the history of dinoflagellates through geological time. Cysts of many of the more common dinoflagellate species have distinctive morphologies allowing their geographic and stratigraphic occurrences to be traced. An ever-increasing number of taxa are also being shown to produce distinctive cysts, potentially increasing our knowledge of the diverse representation of dinoflagellates through time. Here the organic-walled cysts of 73 rare, poorly known or morphologically problematic marine dinoflagellate cyst species belonging to the orders Gymnodiniales (nine species) and Peridiniales (64 species) are reviewed, described and illustrated, and their stratigraphic ranges assessed. The names Echinidinium aculeatum and Echinidinium transparantum are validated herein. Highlights ► 73 rare and endemic marine dinoflagellate cyst species are reviewed, described and illustrated. ► 9 belong to Gymnodiniales and 64 to Peridiniales. ► Echinidinium aculeatum and Echinidinium transparantum are validated.

Paleoceanography and dinoflagellate cyst stratigraphy across the Lower–Middle Pleistocene Subseries (Calabrian–Chibanian Stage) boundary at the Chiba composite section, Japan

“…The present study largely follows the taxonomy of Van Nieuwenhove et al (2020), Mertens et al (2020), and Limoges et al (2020) for the dinoflagellate cysts, except that the cosmopolitan cyst morphotype (Fig. 8j-l, Fig.…”

“…Owing to variable preservation, all smooth-walled round brown acavate cysts were labeled as "round brown cysts." They are assumed to belong overwhelmingly to the genus Brigantedinium but because of folding, an archeopyle was seldom clearly observed and we cannot exclude the possibility that diplopsalid species bearing theropylic archeopyles (e.g., see Mertens et al 2020) are also represented. On rare occasion where the archeopyle could be seen clearly, Brigantedinium simplex and Brigantedinium cariacoense (Fig.…”

Laboratory Culture-Based Characterization of the Resting Stage Cells of the Brown-Tide-Causing Pelagophyte, Aureococcus anophagefferens

“…RSCs of A. anophagefferens have a relatively smooth cell surface, which is different from the resting cysts or spores of many species that undergo more substantial changes in cell surface and/or surface structures including thickened walls or modified enclosing inorganic or organic thecae, as seen in dinoflagellates and some diatoms [27,[47][48][49][50][51]. Similar to vegetative cells, RSCs of A. anophagefferens are spherical in shape, but are so different from vegetative cells in cell size: RSCs are significantly larger (doubled in cell diameter).…”

Dinoflagellate cysts production, excystment and transport in the upwelling off Cape Blanc (NW Africa)

“…Cyst concentrations were calculated by multiplying the cyst counts with the aliquot fraction and dividing through the volume pumped (L) by the ISP. Taxonomy of organic dinoflagellates was according to Zonneveld and Pospelova (2015); Mertens et al (2020) and van Nieuwenhoven et al (2020). The count data were deposited in the PANGAEA database.…”