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Phthanoperidinium tritonium
Phthanoperidinium "tritonium" Eaton, 1976, p.299–300, pl.17, figs.2–3,6–7; text-figs.23C,24A–B.
Taxonomic senior synonym: Hystrichogonyaulax (now Phthanoperidinium) coroides, according to Fensome et al. (2009, p.54–55). Bujak in Bujak et al. (1980, p.72) considered Phthanoperidnium tritonium to be a taxonomic junior synonym of Phthanoperidinim comatum.
Holotype: Eaton, 1976, pl.17, fig.3; text-figs.24A–B; Bujak et al., 1980, pl.5, figs.7–8.
Age: early-middle Eocene (see Aubry, 1986).
Original diagnosis: Eaton, 1976, p. 299
Cyst body has a smooth surface, and a subcircular or rounded polygonal outline modified by a short blunt apical horn. Plate boundaries marked by thin smooth sutural crests of variable height, bearing erect or curved solid spines which may be distally simple or bifurcate. Cingular zone clearly defined and distinctly helicoid. Reflected tabulation 4", 3a, 7", 5""", 2""""; archaeopyle intercalary, formed by displacement of plate 2a.
Dimensions: Holotype: cyst body 44 x 37 µm; length of spines up to 7 µm. Observed range: cyst body 30 x 26 µm to 56 x 46 µm; length of spines up to 13 µm. (n = 22).
Affinities:
Eaton, 1976, p. 299-300: In some specimens, in addition to plate 2a (the operculum), plate 4" is also displaced (Pl.17, fig.7), and in one specimen all three intercalary plates have been lost, probably owing to sutural weakness. In overall form Phthanoperidinium tritonium is similar to P. comatum (Morgenroth 1966), which is distinguished by its consistently longer spines (maximum 28 µm, majority 14-22 µm). The sutural crests in P. tritonium are similar to those of P. alectrolophum, though in the latter species the crests bear numerous short simple spines, while in P. tritonium they are longer, more widely spaced, and may be distally bifurcate.
Taxonomic senior synonym: Hystrichogonyaulax (now Phthanoperidinium) coroides, according to Fensome et al. (2009, p.54–55). Bujak in Bujak et al. (1980, p.72) considered Phthanoperidnium tritonium to be a taxonomic junior synonym of Phthanoperidinim comatum.
Holotype: Eaton, 1976, pl.17, fig.3; text-figs.24A–B; Bujak et al., 1980, pl.5, figs.7–8.
Age: early-middle Eocene (see Aubry, 1986).
Original diagnosis: Eaton, 1976, p. 299
Cyst body has a smooth surface, and a subcircular or rounded polygonal outline modified by a short blunt apical horn. Plate boundaries marked by thin smooth sutural crests of variable height, bearing erect or curved solid spines which may be distally simple or bifurcate. Cingular zone clearly defined and distinctly helicoid. Reflected tabulation 4", 3a, 7", 5""", 2""""; archaeopyle intercalary, formed by displacement of plate 2a.
Dimensions: Holotype: cyst body 44 x 37 µm; length of spines up to 7 µm. Observed range: cyst body 30 x 26 µm to 56 x 46 µm; length of spines up to 13 µm. (n = 22).
Affinities:
Eaton, 1976, p. 299-300: In some specimens, in addition to plate 2a (the operculum), plate 4" is also displaced (Pl.17, fig.7), and in one specimen all three intercalary plates have been lost, probably owing to sutural weakness. In overall form Phthanoperidinium tritonium is similar to P. comatum (Morgenroth 1966), which is distinguished by its consistently longer spines (maximum 28 µm, majority 14-22 µm). The sutural crests in P. tritonium are similar to those of P. alectrolophum, though in the latter species the crests bear numerous short simple spines, while in P. tritonium they are longer, more widely spaced, and may be distally bifurcate.