Browsing by Author "Gu, HF"

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    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
    Mertens, KN; Gu, HF; Gurdebeke, PR; Takano, Y; Clarke, D; Aydin, H; Li, Z; Pospelova, V; Shin, HH; Li, Z; Matsuoka, K; Head, MJ
    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 everincreasing number of taxa are also being shown to produce distinctive and geologically preservable cysts, potentially enhancing 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.
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    Cyst-theca relationship and phylogenetic positions of Scrippsiella plana sp nov and S-spinifera (Peridiniales, Dinophyceae)
    Luo, ZH; Mertens, KN; Bagheri, S; Aydin, H; Takano, Y; Matsuoka, K; McCarthy, FMG; Gu, HF
    Species belonging to the dinophyte genus Scrippsiella are frequently reported in marine waters, but information on their distribution in brackish environments is limited. Here we describe a new species, S. plana, through incubation of non-calcified cysts from sediments collected in the South China Sea and Caspian Sea. The vegetative cells consist of a conical epitheca and a rounded hypotheca with the plate formula of Po, X, 4, 3a, 7, 5C+t, 5S, 5, 2. It differs from other Scrippsiella species by its flattened body in dorsoventral view and a small first anterior intercalary (1a) plate (half the size of plate 3a). Scrippsiellaplana strains from the South China Sea and Caspian Sea share identical internal transcribed spacer (ITS) sequences, and show phenotypic plasticity and local adaptation in growth rate at various salinities, consistent with the environments in which they originated. In addition, two strains of S. spinifera were obtained by incubating ellipsoid cysts with calcareous spines from sediments collected along the Turkish and Hawaiian coast. They also share identical ITS sequences and differ from Duboscquodinium collinii (a parasite of tintinnids) only at two base pair positions (in the ITS2 region). Molecular phylogeny based on ITS and large subunit ribosomal DNA (LSU rDNA) sequences revealed that S. plana was nested within the Calciodinellum (CAL) clade and S. spinifera within the S. trochoidea (STR) clade. The phylogenetic position of Peridinium' wisconsinense is reported for the first time, which supports multiple transitions of the Peridiniales to freshwater.
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    The dinoflagellate cyst genera Achomosphaera Evitt 1963 and Spiniferites Mantell 1850 in Pliocene to modern sediments: a summary of round table discussions
    Mertens, KN; Van Nieuwenhove, N; Gurdebeke, PR; Aydin, H; Bogus, K; Bringué, M; Dale, B; De Schepper, S; de Vernal, A; Ellegaard, M; Grothe, A; Gu, HF; Head, MJ; Heikkilä, M; Limoges, A; Londeix, L; Louwye, S; Marret, F; Masure, E; Matsuoka, K; Mudie, PJ; Penaud, A; Pospelova, V; Price, AM; Ribeiro, S; Rochon, A; Sangiorgi, F; Schreck, M; Torres, V; Uzar, S; Versteegh, GJM; Warny, S; Zonneveld, K
    We present a summary of two round-table discussions held during two subsequent workshops in Montreal (Canada) on 16 April 2014 and Ostend (Belgium) on 8 July 2015. Five species of the genus Achomosphaera Evitt 1963 and 33 of the genus Spiniferites Mantell 1850 emend. Sarjeant 1970 occuring in Pliocene to modern sediments are listed and briefly described along with remarks made by workshop participants. In addition, several holotypes and topotypes are reillustrated. Three species previously assigned to Spiniferites are here considered/accepted as belonging to other genera: Impagidinium inaequalis (Wall and Dale in Wall et al. 1973) Londeix et al. 2009, Spiniferites? rubinus (Rossignol 1962 ex Rossignol 1964) Sarjeant 1970, and Thalassiphora balcanica Baltes & 1971. This summary forms the basis for a set of papers that follows, where points raised during the workshops are explored in greater detail.