From Fensome et al., 2019:
Achomosphaera hyperacantha, (Deflandre and Cookson, 1955, p.264–265, pl.6, fig.7) Davey and Williams, 1969, p.4.
Holotype: Deflandre and Cookson, 1955, pl.6, fig.7.
NOW Spiniferites.
Originally Hystrichosphaera, subsequently Achomosphaera, thirdly (and now) Spiniferites.
Taxonomic junior synonym (at specific rank): Hystrichosphaera furcata var. multiplicata, according to Matsuoka (1985a, p.35) — however, Londeix et al. (2009, p.66) and Mertens et al. (2018a, p.23,34) retained both taxa.
Motile equivalent: Gonyaulax spinifera complex, according to Matsuoka et al. (1989, p.94).
Age: Miocene.

Locus typicus: Balcombe Bay, Victoria

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Original description as Hystrichosphaera hyperacantha: [Deflandre and Cookson, 1955, p. 264]:

Diagnosis:
Shell globular, spherical or almost spherical; polygonal fields characteristic of the genus with fine, sometimes almost indistinguishable outlines, the equatorial series recognizable by the alignment of the processes Stalks of processes long, stiff, often slender, divided unto 3 distinct branches with simple or bifurcate apices, inserted both at the angles of the fields and along their sides, the usual arrangement being 1 process to each angle of the field and 2 along each side.

Dimensions:
Diameter of shell 54-59 µm, overall diameter 92-97 µm, length of processes 13-20 µm.