From Williams et al., 2017:

[Hyalosphaera, Prauss, 1989, p. 23
Name illegitimate: senior homonym: Hyalosphaera Volkheimer and Salas, 1976, an acritarch genus.

Type species: Hyalosphaera ephemera, Prauss, 1989 (pl.5, fig.11; text-fig.6)]

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Original description: [Prauss, 1989]:

Diagnosis:
Cyst scolochorate/cavate. Endoblast sphaeroidal, periblast obovoidal to subpolygonal. Areation because of the extremely thin wall and intensive folding usually difficult to distinct. It may be peridinoid: XPR, X`, ?a, ?7``, Xc, ?5```, ?2````/3````, Xs.
Archeopyle not indicated.
The on the periblast developed areation consists of finate, long, thin processes. These are brod at the base and often connected by low, finate ridges. Processes massive. Ornamented with peniareate scabrae and one larger granulum at the apex.

Affinities:
Hystrichodinium Deflandre emend. Clarke and Verdier is scolochorate/acavate and gonyaulacoid.