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Dissiliodinium caddaense

Dissiliodinium caddaense (Filatoff, 1975, p.89-90, pl.29, figs.7-9) Stover and Helby, 1987a, p.107.

Originally Chytroeisphaeridia, subsequently (and now) Dissiliodinium.

Holotype: Filatoff, 1975, pl.29, fig.7; Helby et al., 1987, figs.16A-B.
Locus typicus: Perth Basin Western Australia
Age: Bajocian.

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

Dissiliodinium caddaense (Filatoff, 1975) Stover and Helby, 1987a. According Stover and Helby (1987a), this species has a small antapical bulge or nipple-like protrusion up to 12 µm long. The autophragm is shagreenate, scabrate to granulate. Compound archeopyle formed from the release of 3-5 precingular paraplates, the apical series remaining attached to the hypocyst by a relatively wide isthmus consisting of paraplate 6" and the sulcal tongue. Paraplates 1" through 5" are usually freed during archeopyle formation, however, they may be adherent. Dissiliodinium caddaense differs from D.globulum in having the antapical bulge and in being larger. Size: width 95-150 µm.
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Orignal description: Filatoff 1975, p. 89-90: Chytroeisphaeridia caddaensis
Vesicle shape difficult to determine because the specimens are normally fragmented and only rarely complete. Shape apparently ovoid with an apical archaeopyle and a small antapical horn. Wall thin (0.5 Ám thick) commonly folded and torn. Sculpture granulate with rare spinulae; grana 0.5--1 Ám in diameter and about 1 Ám apart. Tabulation is not evident.

Dimensions: Length: 82(98)120 Ám. Breadth: 48(57)67 Ám.

Remarks: Chytroeisphaeridia caddaensis is distinguished by its large size, thin granulate wall, and small antapical horn. The sculpture of C. caddaensis is similar to that of Canningia colliveri COOKSON & EISENACK, 1960, but the latter has a broad base with two antapical horns.

Occurrence: Chytroeisphaeridia caddaensis is abundant in many samples from the Cadda Formatation
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