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Satyrodinium haumuriense

Satyrodinium haumuriense (Wilson, 1984) Lentin and Manum, 1986

Originally Isabelidinium, subsequently Isabelidinium?, thirdly (and now) Satyrodinium
Holotype: Wilson, 1984, figs.14-15
Locus typicus: Haumuri Bluff, Marlborough, New Zealand, grid reference 032/517505
Stratum typicum: Haumurian Stage, Upper Cretaceous

Original description: Wilson, 1984, p.554: Isabelidinium haumuriense
Cyst elongate, bicavate, rhomboidal, divided into approximately equal epicyst and hypocyst. Apex broadly truncated, though usually with a central notch or short rounded projection. Relatively long pointed left antapical horn developed: right antapical horn absent or poorly developed. Periphragm fairly thin and adorned with numerous small granules, especially near the poles. Endocyst very thin walled, somewhat indistinct, smooth, and usually in close contact only with central part of pericyst; prominent pericoels developed between endocyst and poles. Archeopyle relatively narrow (periarcheopyle index 0.4 to 0.6), elongate, hexagonal; operculum free. Paracingulum is occasionally defined by very faint parallel lineations on periphragm surface. No paratabulation evident although longitudinal lineations sometimes visible on dorsal pericyst.
Dimensions: Holotype: overall length 157 µm, breadth 83 µm, antapical horn 22 µm. Range (20 specimens): length 127(163)205 µm, breadth 70(83)95 µm.

Affinities:
Wilson, 1984, p.554: Isabelidinium haumuriense
Isabelidinium haumuriense is distinguished from other species of Isabelidinium mainly by its distinctive truncated apex and in having a relatively prominent left antapical horn. A specimen (subsequently lost) illustrated by Cookson and Eisenack from Australia appears to be very similar to 1. haumuriense (Cookson and Eisenack 1982, pl.2, fig.11).
The species is fairly widespread and abundant inthe Haumurian (uppermost Cretaceous), including the stratotype, in New Zealand. Its occurrence in the overlying Teunan at certain localities, along with other Late Cretaceous taxa, is attributed to reworking.
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