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Trivalvadinium formosum
From Fensome et al., 2019:
Trivalvadinium formosum Islam, 1983b, p.346, pl.4, fig.9.
Holotype: Islam, 1983b, pl.4, fig.9; Fensome et al., 1995, fig.1 — p.1487.
Locus typicus: Hampshire Basin, S England
Stratum typicum: Middle Eocene
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Original diagnosis: Islam, 1983, p. 346
Cyst peridinioid, rounded pentagonal, laterally to dorsoventrally compressed, proximochorate, acavate, cornucavate or discontinuously circumcavate, and biphragmal; both phragma mildly chagrinate; horns, if present, vestigial, apical and two antapical horns only; many or relatively fewer solid, tubular or thinly tubular nontabular processes all distally aculeate and open when hollow, sometimes proximally joined in pairs; paracingulum sometimes partially indicated by periphragmal folds; archeopyle intercalary type 3I/3I, sometimes enlarged with irreqular margins.
Dimensions: Holotype: cyst body 55 x 56 µm, length of processes 5-10 µm. Range: cyst length 58(53)47 µm, breadth 60(52)42 µm, length of processes 3-11 µm. Specimens measured: 10.
Affinities:
Islam, 1983, p. 346: In process morphology, the species resembles Apectodinium sumissum Harland 1980 and A. folliculum Islam but differs in possessing 3I/3I archeopyle. The species appears to favor a brackish water environment.
Trivalvadinium formosum Islam, 1983b, p.346, pl.4, fig.9.
Holotype: Islam, 1983b, pl.4, fig.9; Fensome et al., 1995, fig.1 — p.1487.
Locus typicus: Hampshire Basin, S England
Stratum typicum: Middle Eocene
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Original diagnosis: Islam, 1983, p. 346
Cyst peridinioid, rounded pentagonal, laterally to dorsoventrally compressed, proximochorate, acavate, cornucavate or discontinuously circumcavate, and biphragmal; both phragma mildly chagrinate; horns, if present, vestigial, apical and two antapical horns only; many or relatively fewer solid, tubular or thinly tubular nontabular processes all distally aculeate and open when hollow, sometimes proximally joined in pairs; paracingulum sometimes partially indicated by periphragmal folds; archeopyle intercalary type 3I/3I, sometimes enlarged with irreqular margins.
Dimensions: Holotype: cyst body 55 x 56 µm, length of processes 5-10 µm. Range: cyst length 58(53)47 µm, breadth 60(52)42 µm, length of processes 3-11 µm. Specimens measured: 10.
Affinities:
Islam, 1983, p. 346: In process morphology, the species resembles Apectodinium sumissum Harland 1980 and A. folliculum Islam but differs in possessing 3I/3I archeopyle. The species appears to favor a brackish water environment.