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Canninginopsis bretonica
From Fensome et al., 2019:
Canninginopsis bretonica Marshall, 1990b, p.84–86, figs.4L–T,5F–H,6L–U.
Holotype: Marshall, 1990b, figs.4N,5F–G,6N–O; Fensome et al., 1996, figs.1–2,7 — p.2069; Fensome et al., 2019a, figs.13S–T.
Age: late Campanian–middle Maastrichtian.
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Original description: [Marshall, 1990, p. 84, 86]:
Description:
Cysts lenticular; ventrodorsal outline subcircular to subpentagonal; modified by an apical and 2 antapical horns forming rounded bulges, or broadly subconical structures with bluntly rounded tips. Lateral margins broadly convex or modified by 2 horns defining equatorial rounded bulges. Autophragm 0.5-1.0 µm thick along lateral margins. Dorsal and edges of ventral surfaces finely foveolate; lacunae discrete, subcircular to oval, up to 1 µm in maximum dimension, or coalescing to form sinuous furrows c. 0.5 µm wide. Furrows isolated or interconnected in irregular networks. Midventral surface smooth and unsculptured.
Paratabulation usually clearly indicated on dorsal and edges of ventral surfaces by parasutural septa up to 7 µm high (Fig. 5G, H); fragments of parasutural boundaries occasionally outlined by 2 close-spaced rows of penitabular septa. Septa bear numerous perforations less than 2 µm in diameter; perforations frequently fragment distal margins of septa, producing irregularly denticulate ridges. Transverse boundaries of equatorial paraplates slightly zigzag. Anterior margin of paraplate 2 planate to camerate.
Paracingulum indicated by parasutural features and a shallow transverse groove 4-6 µm wide.
Dimensions:
Cyst without operculum: length 58(67)76 µm; width 57(82)103 µm (18 specimens).
Holotype: autocyst length 71 µm, width 81 µm.
Affinities:
The ventral surface on C. bretonica is difficult to identify under the optical microscope because of the extreme thinness of the autophragm. The paratabulation on the dorsal surface closely resembles that on Canninginopsis denticulata (Fig. 5). The triple junctions of some paraplates on C. bretonica appear to be marked by two closely spaced, often partially fused rows of septa rather than just a single parasutural row. This apparent definition of paratabulation by one or two rows of sculpture may be analogous to that on C. denticulata.
Canninginopsis bretonica Marshall, 1990b, p.84–86, figs.4L–T,5F–H,6L–U.
Holotype: Marshall, 1990b, figs.4N,5F–G,6N–O; Fensome et al., 1996, figs.1–2,7 — p.2069; Fensome et al., 2019a, figs.13S–T.
Age: late Campanian–middle Maastrichtian.
---------------------------------------------------------------------------------------------------
Original description: [Marshall, 1990, p. 84, 86]:
Description:
Cysts lenticular; ventrodorsal outline subcircular to subpentagonal; modified by an apical and 2 antapical horns forming rounded bulges, or broadly subconical structures with bluntly rounded tips. Lateral margins broadly convex or modified by 2 horns defining equatorial rounded bulges. Autophragm 0.5-1.0 µm thick along lateral margins. Dorsal and edges of ventral surfaces finely foveolate; lacunae discrete, subcircular to oval, up to 1 µm in maximum dimension, or coalescing to form sinuous furrows c. 0.5 µm wide. Furrows isolated or interconnected in irregular networks. Midventral surface smooth and unsculptured.
Paratabulation usually clearly indicated on dorsal and edges of ventral surfaces by parasutural septa up to 7 µm high (Fig. 5G, H); fragments of parasutural boundaries occasionally outlined by 2 close-spaced rows of penitabular septa. Septa bear numerous perforations less than 2 µm in diameter; perforations frequently fragment distal margins of septa, producing irregularly denticulate ridges. Transverse boundaries of equatorial paraplates slightly zigzag. Anterior margin of paraplate 2 planate to camerate.
Paracingulum indicated by parasutural features and a shallow transverse groove 4-6 µm wide.
Dimensions:
Cyst without operculum: length 58(67)76 µm; width 57(82)103 µm (18 specimens).
Holotype: autocyst length 71 µm, width 81 µm.
Affinities:
The ventral surface on C. bretonica is difficult to identify under the optical microscope because of the extreme thinness of the autophragm. The paratabulation on the dorsal surface closely resembles that on Canninginopsis denticulata (Fig. 5). The triple junctions of some paraplates on C. bretonica appear to be marked by two closely spaced, often partially fused rows of septa rather than just a single parasutural row. This apparent definition of paratabulation by one or two rows of sculpture may be analogous to that on C. denticulata.