As of February 2022[update], it contained a single species, Polyedriopsis spinulosa.

[1] Polyedriopsis spinulosa consists of solitary or sometimes clustered cells, 12–25 μm in diameter.

They are four- or five-sided with concave sides; the corners are rounded off and bear a tuft of 3-10 thin tapering spines, 25–50 μm long.

Cells are uninuclate (with one nucleus and contain a single parietal chloroplast with one pyrenoid.

[1][2] Polyedriopsis spinulosa reproduces asexually via the formation of zoospores, of which 4 to 8 are produced per cell.