Xanthidium antilopaeum is a species of unicellular desmid in the family Desmidiaceae.

It is a common, worldwide species found in acidic waters, particularly the edges of large ponds and lakes.

Cell are symmetrical, with a deep constriction (called an isthmus) dividing the cell into two identical halves called semicells.

In each semicell, the four corners are extended into a pair of simple, straight or somewhat curved spines.

This species is distinguished from X. antilopaeum by having spines with a stout base, a central protuberance on the semicells, and a row of the 12-14 small pits located next to the isthmus.