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Fromea staveia
From Fensome et al., 2019:
Fromea staveia Elsik, 1977, p.100,102, pl.2, figs.12–14. Holotype: Elsik, 1977, pl.2, fig.12. Age: Late Eocene.
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Original description (Elsik, 1977):
Fromea staveia n. sp.
Plate 2, figures 12-14
Description: Robust, 65-80 by 65-90 um, oval to circular specimens with a large apical archeopyle 14-22 pm wide. Wall psilate, ± 1 um, of two layers; endophragm thin, often folded and sometimes obscure; periphragm thicker and of generally uniform thickness except at the rim of the apical archeopyle where the periphragm is thickened—the extreme distal margin may be extremely thin. Single equatorial faint scar or suture apparently developed on inner surface of periphragm and apparently represents a cingulum. No evidence of tabulation.
Remarks: Several hundred specimens in the sample exhibit a consistent morphology consisting of a thick periphragm and a very thin and occasionally wrinkled endophragm. None of the specimens exhibited a thin and loosely folded outer layer although the morphology is otherwise as in Ascostomocystis hydria Drugg and Loeblick 1967 (see also illustration in Drugg and Stover, 1975, pi. 1, fig. 7). Differentiated from Fromea amphora Cookson and Eisenack 1958 by possessing a less distinct cingulum, this new species is included here as documentation for the type of obscure cingula possible in some dinocysts.
Occurrence: Late Eocene; abundant in sample from Bandy (1949) collecting locality #55, middle part of Yazoo Clay as exposed at Little Stave Creek, Clarke County, Alabama.
Fromea staveia Elsik, 1977, p.100,102, pl.2, figs.12–14. Holotype: Elsik, 1977, pl.2, fig.12. Age: Late Eocene.
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Original description (Elsik, 1977):
Fromea staveia n. sp.
Plate 2, figures 12-14
Description: Robust, 65-80 by 65-90 um, oval to circular specimens with a large apical archeopyle 14-22 pm wide. Wall psilate, ± 1 um, of two layers; endophragm thin, often folded and sometimes obscure; periphragm thicker and of generally uniform thickness except at the rim of the apical archeopyle where the periphragm is thickened—the extreme distal margin may be extremely thin. Single equatorial faint scar or suture apparently developed on inner surface of periphragm and apparently represents a cingulum. No evidence of tabulation.
Remarks: Several hundred specimens in the sample exhibit a consistent morphology consisting of a thick periphragm and a very thin and occasionally wrinkled endophragm. None of the specimens exhibited a thin and loosely folded outer layer although the morphology is otherwise as in Ascostomocystis hydria Drugg and Loeblick 1967 (see also illustration in Drugg and Stover, 1975, pi. 1, fig. 7). Differentiated from Fromea amphora Cookson and Eisenack 1958 by possessing a less distinct cingulum, this new species is included here as documentation for the type of obscure cingula possible in some dinocysts.
Occurrence: Late Eocene; abundant in sample from Bandy (1949) collecting locality #55, middle part of Yazoo Clay as exposed at Little Stave Creek, Clarke County, Alabama.