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Microdinium irregulare

Microdinium irregulare Clarke and Verdier, 1967

Tax. jr. synonym of Rhiptocorys (as Phanerodinium) ueligera (Deflandre, 1937) Lejeune-Carpentier and Sarjeant, 1983, according to Below, 1987.

Holotype: Davey and Verdier, 1967, pl.7, fig.5
Locus typicus: Isle of Wight, Southern Cliff, England
Stratum typicum: Cenomanian-Santonian

Original diagnosis: Clarke and Verdier, 1967, p.65
This species is characterized by the possession of granae on the plates and well developed smooth ledges.

Description: Clarke and Verdier, 1967, p.66
Outline rounded with a flattened apex. A distinct, broad girdle divides the body into two very unequal parts, the epitheca being much smaller than the hypotheca. The girdle is interrupted but hardly displaced. Longitudinal furrow is well developed. Tabulation distinct, plates bordered by smooth, undulating ledges. Sculpture of the plates consists of granae or verrucae, often densely packed to form a rugulate pattern. However, the spacing of the granae may differ from one plate to another. An archaeopyle is nearly always visible and formed by the loss of the apical plate (or plates).
Dimensions: Holotype: Overall length 34 Ám, overall breadth 36 Ám, width of girdle 4 height of ledges (max.) 5 Ám. Range: Overall length 30-38 Ám, overall breadth 32-39 Ám, width of girdle 4-6 Ám, height of ledges (max.) 4-5 Ám.
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