Diacrocanthidium pumile (O. Wetzel, 1932 ex 0. Wetzel, 1933) emend. Sarjeant, 1985

Name illegitimate; nomencl. jr. synonym of Hystrichosphaera (now Baltisphaeridium) longispinosa forma longispinosa, the potential autonym since, in validating Hystrichosphaera longispinosa forma longispinosa, O. Wetzel, 1933, included in synonymy the holotype of the species. See also Hystrichosphaera longispinosa forma pumilis (name illegitimate), Hystrichosphaera pumile (name illegitimate), Micrhystridium pumile (name illegitimate) and Baltisphaeridium pumile (name illegitimate).
Deflandre, 1937, proposed the elevation of this taxon to specific rank as Hystrichosphaeridium pumile.
Sarjeant, 1985, emended the diagnosis of this species and questionably included it in Diacrocanthidium.
The name Hystrichosphaera longispinosa forma pumilis, although accompanied by a description, was not validly published by O. Wetzel, 1932, since the generic name Hystrichosphaera was not validated until 1933. In validly publishing, but not legitimizing, the name Hystrichosphaera longispinosa forma pumilis, O. Wetzel, 1933, illustrated only one specimen but listed in synonymy several more, including the holotype of the species; he did not designate any of these specimens as holotype. Based on reexamination of the single specimen illustrated by O. Wetzel, 1933, which he indicated as holotype, Sarjeant, 1985, proposed the transfer of this taxon (questionably) to Diacrocanthidium.
Holotype: O. Wetzel, 1933, pl.4, fig.23 (designated by Sarjeant, 1985)
Age: Late Cretaceous (based on material from an erratic)