From Williams et al., 2017:

[Anthosphaeridium, Cookson and Eisenack, 1968, p. 115

Fensome and Williams (2004) were incorrect in listing this as an acritarch genus. It's dinoflagellate affinity was confirmed by Schiøler and Wilson (1998, p323), who described an archeopyle for the type.

Type species: Anthosphaeridium convolvuloides, Cookson and Eisenack, 1968 ( fig.4A)]

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Original description: [Cookson and Eisenack, 1968]:

Description:
Shell typically spherical, completely covered with short, densely arranged, striated, funnel-shaped appendages.