Operculodinium hirsutum ssp. amplum (W. Wetzel, 1956) Lentin and Williams, 1973; Emendation: Sarjeant, 1984c, p.131, as Operculodinium centrocarpum subsp. amplum.

Name not validly published.
Now Operculodinium centrocarpum ssp. amplum. Originally Hystrichosphaeridium hirsutum ssp. amplum (name not validly published), subsequently Operculodinium hirsutum? ssp. amplum (name not validly published), thirdly (and now) Operculodinium centrocarpum ssp. amplum. See also Baltisphaeridium hirsutum ssp. amplum (name not validly published).

Holotype: W. Wetzel, 1955, text-fig.11; Sarjeant, 1984, pl.3, figs.1-3, text-fig.4
Age: Danian

Original diagnosis: W. Wetzel, 1952, p. 38: Hystrichosphaeridium hirsutum ssp. amplum
An analogous case to the form described above [Hystrichosphaeridium pseudhystrichodinium magnum] exists, since to the small-sized Senonian species may be allocated, as subspecies, the Danian forms, which in terms of dimensions almost equal the subspecies pseudhystrichodinium magnum, [but] which however approach, in their dense and fine spinosity, the older species hirtum [sic]. The maximum diameter attains 132 Ám, with 96 Ám capsule diameter.

Emended diagnosis: Sarjeant, 1984, p. 131
Proximochorate, cryptotabulate dinoflagellate cysts of spherical or very broadly spheroidal ambitus. Spines numerous, around 30 being visible round the periphery in ambital view, the total number being in the range 60 to 70. The spines may be gonal and intergonal in situation or may be nontabular; they are broad-based, but thereafter taper only slightly to a simple, acuminate to evexate tip. Length of spines c. 20-25 % of the diameter of the central body. Surface of phragma granulate. Archaeopyle single-plate precingular (type P).
Dimensions. Diameter of central body 96 Ám, length of spines in the range 19-24 Ám.