Pyxidinopsis "spinosus" Zevenboom and Santarelli in Zevenboom, 1995, p.155, pl.9, figs.9–11.
Holotype: Zevenboom, 1995, pl.9, figs.9–11. Name not validly published: considered a manuscript name.
The epithet is correctly rendered as "spinosus", not "spinosis".
Age: middle Miocene–earliest late Miocene.

Original description (Zevenboom, 1995)
Manuscript holotype: Sample Mazza 40, Sg. A 43/2, Plate IX, 9-11
Etmology: In reference to the spinose character of the processes.
Type locality: Cassinasco section, Tertiary Piedmont Basin, North Italy.
Type stratum: Cessole formation.
Diagnosis: An ellipsoidal species of Pyxidinopsis with short hollow distally closed spines.
Dimensions: Height (45(53)60 µm; Width: 30(37)45 µm; Processes 2-4(2-4.5)2-5 µm. N=23.
Description: An ellipsoidal species of Pyxidinopsis with a finely granular periphragm. Endo- and periphragm are closely appressed except beneath the hollow spines. The spines are short, hollow, conical and distally closed. The archaeopyle is formed by the loss of plate 3", operculum free.
Discussion: Pyxidinopsis spinosis differs from the morphologically similar Operculodinium janduchenei Head, 1989b, by being elongate rather than spherical and from all other species of Pyxidinopsis in possessing short hollow conical spines. It differs from Pyxidinopsis protospinosis Zevenboom and Santarelli 1995, by lacking a reticulum and by having hollow rather than solid processes. We attribute this species to Pyxdinopsis rather than to Operculodinium Wall, 1967, in view of the overall shape of the cyst.
Occurrence: Italy (this study)
Stratigraphic range: Middle Miocene to basal Late Miocene (this study).