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Phthanoperidinium multispinum

From Fensome et al., 2019:
Phthanoperidinium multispinum Bujak in Bujak et al., 1980, p.74, pl.19, figs.17–19; text-fig.20F. Holotype: Bujak et al., 1980, pl.19, fig.18. Age: Middle Eocene (see Aubry, 1986).

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Paratype: Bujak in Bujak et al., 1980
Locus typicus: Whitecliff Bay, Isle of Wight, S England
Stratum typicum: Late Eocene

Original description: Bujak in Bujak et al., 1980, p. 74
Diagnosis: Pericyst ovoidal with one apical and one or two unequal antapical horns. An endocyst is rarely visible. The periphragm is chagrinate to granulate, with low membranous crests which delimit a paratablutaion of 4', 3a, 7'', xc, 5''', 2''''. The crests bear closely spaced, solid, simple or bifurcate spines that are up to 6 µm long. Concentration of coarse granules on the periphragm may result in simulate rings within the paraplates. The archaeopyle is formed by the loss of paraplate 2a.

Dimensions: Pericyst length = 35-45 µm, breadth = 30-37 µm. Maximum crest height = 2-4 µm. Maximum spine height = 4-6 µm. 6 specimens measured.

Affinities:
Bujak in Bujak et al., 1980; P. multispinum is distinguished from P. alectrolophum Eaton, 1976, in having longer spines. However, they are not as long as in P. comatum.
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