Williams, Lentin and Fensome 1998 - Lentin and Williams Index of Fossil Dinoflagellates

Achomosphaera grallaeformis, (Brosius, 1963, p.42, pl.5, fig.3; text-fig.2), Davey and Williams, 1969, p. 4.

Originally Hystrichosphaeridium, subsequently (and now) Achomosphaera. This combination was not validly published in Davey and Williams (1966b, p.104), since these authors did not fully reference the basionym.

Holotype: Brosius, 1963, pl.5, fig.3.
Locus typicus: Deute, Mtb. Gudenberg, Germany
Age: Oligocene

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Original description as Hystrichosphaeridium grallaeformis: [Brosius, 1963, p.42] (Translation: LPP):

Diagnosis:
The round, two-layered capsule bears hollow, furcate processes, resembling those of H. ramuliferum. Ends often open or bearing little thorns. Processes build up by outer membrane. Bases of processes stilt-rood shaped, may be joined, wide and thin processes possible on one specimen. Both wall layers regularly perforate.

Dimensions:
Capsule diameter (without processes) 40 µm, length of processes 17 µm. Number of processes 20.