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Vesperopsis pseudovitrea
Vesperopsis pseudovitrea (Lister and Batten, 1988) Harding, 1990
Originally Australisphaera, subsequently (and now) Vesperopsis.
Holotype: Lister and Batten, 1988, pl.3, fig.3; text-fig.6B, no.1.
Age: latest Barremian
Original description (batten & Lister, 1988):
Australisphaera pseudovitrea Lister & Batten n.sp. (Pl. 3, Fis. 2, 3; Tekst-fig. 6
1983 A. vitrea Duxbury pars, p. 26, pl. 3, fig. 5, non pl. 2, fig. 11
Derivation of name: Gk. Pseudos – false, with reference to the close relationship of this species to Australisphaera vitrea Duxbury
Diagnosis: proximate, thin-walled dinoflagellate cyst, ceratoid in outline, possessing one apical , two lateral and usually two antapical horns. Apical horn prominent, distally rounded, occasionally pointed and closed. Lateral horns developed as extensions of paracigulum which is distally notched, sometimes displaying rudimentary, slightly tapered projections below lateral post-paracingular margin. Right lateral horn more pronounced than that on left. Conical, left antapical horn usually more prominent than right, which may be very reduced or absent. Horns sometimes present simply as low buldges of autophragm. Autophrgam exhibits a sparse granular ornament which is particularly concentrated at distal extremities of horns and also party defines paracingulum. Isolated short, rod-like processes and linear or vermiculate arrangements of similar, distally linked elements, also observed on some specimens. Parasulcal area occasionally indicated by a ventral furrow lacking ornament. Arcjheopyle apical, type (tA) with a free operculum; margin slightly to moderately zigzag, accessory sutures indicating presence of six precingular paraplates and a deep offset sulcal notch.
Dimensions: Length with operculum, 54 (80) 100 µm; length without operculum, 51 (55) 60 µm; width, 55 (67) 77 µm (20 specimens).
Remarks: This species differs from the holotype of A. vitrea Duxbury 1983 and similar forms in lacking pointed, well-developed digitate projections on the lateral horns and high, granular processes at the distal extremities of these and the other horns.
Occurrence: Weald Clay – Atherfield Clay junction.
Originally Australisphaera, subsequently (and now) Vesperopsis.
Holotype: Lister and Batten, 1988, pl.3, fig.3; text-fig.6B, no.1.
Age: latest Barremian
Original description (batten & Lister, 1988):
Australisphaera pseudovitrea Lister & Batten n.sp. (Pl. 3, Fis. 2, 3; Tekst-fig. 6
1983 A. vitrea Duxbury pars, p. 26, pl. 3, fig. 5, non pl. 2, fig. 11
Derivation of name: Gk. Pseudos – false, with reference to the close relationship of this species to Australisphaera vitrea Duxbury
Diagnosis: proximate, thin-walled dinoflagellate cyst, ceratoid in outline, possessing one apical , two lateral and usually two antapical horns. Apical horn prominent, distally rounded, occasionally pointed and closed. Lateral horns developed as extensions of paracigulum which is distally notched, sometimes displaying rudimentary, slightly tapered projections below lateral post-paracingular margin. Right lateral horn more pronounced than that on left. Conical, left antapical horn usually more prominent than right, which may be very reduced or absent. Horns sometimes present simply as low buldges of autophragm. Autophrgam exhibits a sparse granular ornament which is particularly concentrated at distal extremities of horns and also party defines paracingulum. Isolated short, rod-like processes and linear or vermiculate arrangements of similar, distally linked elements, also observed on some specimens. Parasulcal area occasionally indicated by a ventral furrow lacking ornament. Arcjheopyle apical, type (tA) with a free operculum; margin slightly to moderately zigzag, accessory sutures indicating presence of six precingular paraplates and a deep offset sulcal notch.
Dimensions: Length with operculum, 54 (80) 100 µm; length without operculum, 51 (55) 60 µm; width, 55 (67) 77 µm (20 specimens).
Remarks: This species differs from the holotype of A. vitrea Duxbury 1983 and similar forms in lacking pointed, well-developed digitate projections on the lateral horns and high, granular processes at the distal extremities of these and the other horns.
Occurrence: Weald Clay – Atherfield Clay junction.