From Williams et al., 2017:

[Adnatosphaeridium, Williams and Downie, 1966c, p. 215; Emendations: Stancliffe and Sarjeant, 1990, p. 199-200

Type species: Adnatosphaeridium vittatum, Williams and Downie, 1966c (pl.24, fig.7; text-fig.56)]

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Original description: [Williams and Downie, 1966]:

Diagnosis: Chorate cyst bearing tubular or solid intratabular processes varying in number on a single plate. Processes united distally by interconnecting trabeculae. Archaeopyle apical.

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Modified description:

Stover and Evitt 1978, p. 14-15:

Synopsis: Cysts skolochorate, body subspherical with solid or hollow processes, tubular to funnelform, intratabular processes; adjacent processes connected distally by ribbonlike to fenestrate trabeculae; archeopyle apical, Type tA.

Description:
Shape: Body subspherical.
Wall relationships: Autophragm forms body and processes; ectophragm forms slender and smooth to relatively wide and fenestrate trabeculae that extend between the distal ends of processes.
Wall features: No parasutural features. Processes solid or more commonly hollow, tubular to funnelform, distally branched or fenestrate; adjacent processes connected distally by trabeculae. Autophragm smooth to faintly ornamented.
Paratabulation: Apparently indicated by intratabular processes; formula not yet documented, presumably gonyaulacacean.
Archeopyle: Apical, Type tA; operculum free.
Paracingulum: Generally indistinguishable, occasionally discernible by alignment of the more slender processes or by relationship to archeopyle margin.
Parasulcus: Usually not discernible.
Size: Intermediate to large.

Affinities:
Adnatosphaeridium differs from Glaphyrocysta in having a spherical rather than a lenticular body, and in generally lacking the process-free areas normally present on Glaphyrocysta.

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Emended description:


Stancliffe and Sarjeant, 1990:

Diagnosis:
A trabeculate dinoflagellate cyst. Central body spherical to ellipsoidal, with a smooth to granular phragma, thin or of moderate thickness. Intratabular processes isolated or in clusters, reflecting a probable paratabulation of 4`, 6", 6c, 5-6```, 1p, 1````, 1-5s. Processes solid or open, medium to long, slender, often distally flared, and sometimes taeniate. Branching occurs distally, though it may also be developed medially, two stages of branching being common. Trabeculae of variable thickness, distally smooth to finely denticulate, are frequently developed, occasionally linking processes into clusters.
Cingulum and sulcus commonly marked by isolated, long thin processes.
Archeopyle apical, type (tA), operculum free, often with a sulcal notch.