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Vectensia varians
Vectensia varians Batten and Lister, 1988
Holotype: Batten and Lister, 1988, fig.3c
Locus typicus: Barnes High Sandstone Member of the Vectis Formation, Isle of Whight
Stratum typicum: Barremian
Original diagnosis: Batten and Lister, 1988, p.349
Small, spherical, variably cavate cyst; maximum diameter 30(37)45 x 32(37)45 µm (20 specimens). Endophragm thin (< 1µm) and of very finely granular, microperforate texture, rarely a finely meshed reticulum. Periphragm also thin (< 1 µm), membraneous, often developed only over part of cyst, may balloon out or form folds against endocyst, usually at apex, antapex and bordering parasulcal area; closely adpressed to endocyst or undeveloped elsewhere. Folds of periphragm can suggest incipient development of muri or crests, sometimes with associated small reticulate structures. Unornamented ridges present on surface of periphragm which, when this is closely adpressed to endocyst, delineate large subcircular to subpolygonal fields that may approximately coincide with some postcingular paraplate boundaries. A full paratabulation is not, however, outlined and frequently these periphragm features are poorly developed or show no obvious association with it. Archeopyle type (tA) or (tAtI), operculum usually adherent, rarely detached, possibly adnate. ?Six or seven camerate precingular paraplates and a deep sulcal notch, separated by deep splitting of accessory sutures, may be visible.
Holotype: Batten and Lister, 1988, fig.3c
Locus typicus: Barnes High Sandstone Member of the Vectis Formation, Isle of Whight
Stratum typicum: Barremian
Original diagnosis: Batten and Lister, 1988, p.349
Small, spherical, variably cavate cyst; maximum diameter 30(37)45 x 32(37)45 µm (20 specimens). Endophragm thin (< 1µm) and of very finely granular, microperforate texture, rarely a finely meshed reticulum. Periphragm also thin (< 1 µm), membraneous, often developed only over part of cyst, may balloon out or form folds against endocyst, usually at apex, antapex and bordering parasulcal area; closely adpressed to endocyst or undeveloped elsewhere. Folds of periphragm can suggest incipient development of muri or crests, sometimes with associated small reticulate structures. Unornamented ridges present on surface of periphragm which, when this is closely adpressed to endocyst, delineate large subcircular to subpolygonal fields that may approximately coincide with some postcingular paraplate boundaries. A full paratabulation is not, however, outlined and frequently these periphragm features are poorly developed or show no obvious association with it. Archeopyle type (tA) or (tAtI), operculum usually adherent, rarely detached, possibly adnate. ?Six or seven camerate precingular paraplates and a deep sulcal notch, separated by deep splitting of accessory sutures, may be visible.