Impagidinium plicatum Versteegh and Zevenboom, 1995

Holotype: Versteegh and Zevenboom, 1995, pl. III, fig. 1-3
Type Locality: Piston core T20-87, off Crete
Type stratum:

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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.

Impagidinium plicatum Versteegh and Zevenboom in Versteegh, 1995, is ovoid to elongate with suturocavate crenulate crests. The plate formula is 4', 6", 6c, 6"’, 1p, 1"”. The reflected tabulation varies. There are no septa in the sulcal area and between the sulcus and 1"’. Size: height 28-38 µm, maximum diameter 24-34 µm, height of septa 2-4 µm.
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Diagnosis: Versteegh and Zevenboom, 1995, p. 221
Ovoid to elongate Impagidinium cysts with suturocavate crenulate septa. The plate formula is 4', 6'',6c, 6''', 1p, 1''''. The reflected tabulation varies.

Description: Versteegh and Zevenboom, 1995, p. 221, 223
Of this Impagidinium species with crenulate septa, specimens with maximally reflected tabulation lack septa between, the sulcal plates, and sulcus/1'''. Specimens with minimally reflected tabulation lack also septa between 1'/4', sulcus/1p, sulcus/6'', 1''/1c, 1c/2''' and 6c/6'''. Nearly all forms examined are of the type with minimally reflected tabulation, with the exception that weakly developed septa can occur between: sulcus/1p, 6c/6''' and 1''/1c.
Only one specimen with maximally reflected tabulation was encountered. This specimen represents also the earliest record of this species so far.
Dimensions: Holotype: height: 32 µm; maximum diameter: 27 µm; height of septa 2 µm. Range : height: 28-38 µm; maximum diameter: 24-34 µm; height of septa 2-4 µm; specimens measured: 14.

Affinities:
Versteegh and Zevenboom, 1995, p. 223
The crenulate septa differentiate this species from all other species of Impagidinium.

Stratigraphy: Earliest Zanclean (this paper) to Versilian (Zonneveld, in press.)