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Heterosphaeridium spinaconjunctum

Heterosphaeridium spinaconjunctum Yun, 1981

Holotype: Yun, 1981, pl.3, fig.11; Fensome et al., 1991, fig.2 - p.749
Paratype: Yun, 1981, pl.3, fig.8
Locus typicus: Timmermann brickyard near Esbeck, Germany
Stratum typicum: early Santonian
Translation Yun, 1981: Fensome, 1991, p. 750

Original diagnosis: Yun, 1981, p.47
Proximate-proximochorate cyst with a central body of round to rounded-quadrangular outline. Spines simple, variously forked, with widened and truncated distal ends and partly with groups of two or three spines interconnected distally by a short membrane. An apical archeopyle occurs at 2/3-3/4 the central body height.

Original description: Yun, 1981, p. 47
The cyst has a smooth endophragm (in one specimen 1.2 Ám thick) and a perforated periphragm (1.5 Ám thick in the same specimen). The oval to teardrop-shaped perforations are "fibrously" arranged. The solid flattened, imperforate spines are formed by the periphragm; their length varies in places, depending on their position on the central body. In the antapical and paracingular areas the spines are usually longer. They are sometimes of constant uniform width, simple or forked into two or three branches differing in thickness. Apart from these isolated spines, there are occasionally spines which are interconnected by distal widenings or strands in the form of an archway. The distal widenings are asymmetrical and of varying size.
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