The fungus produces small pinkish-buff fruit bodies up to 0.6 cm (0.24 in) in diameter, with distantly spaced narrow gills.

[1] The holotype material was collected by Desjardin in January, 1996 in the Kamakou Forest Preserve on Molokaʻi island.

The specific epithet hapuuarum refers to the name of the hāpuʻu tree fern upon which the fungus grows.

[1] The thin-walled spores are ellipsoid with a prominent hilum, smooth, hyaline (translucent), and measure 8–10 by 4.2–4.8 μm.

The basidia (spore-bearing cells) are club-shaped, hyaline, clamped, and are attached to anywhere from one to four spores; they measure 20–24 by 7–8 μm.