Ionaspis aptrootii is a species of saxicolous (rock-dwelling), crustose lichen in the family Hymeneliaceae.

[4] The type specimen was collected by Aptroot in Varirata National Park, Papua New Guinea, where he found it growing on conglomerate rock at an elevation of 700 m (2,300 ft).

[5] Ionaspis aptrootii has a smooth, cream-white thallus up to 1 mm thick and encircled with a black prothallus.

It has angular to star-shaped (stellate), dark reddish-brown apothecia (fruiting bodies) that are immersed in the thallus, and measure 0.2–0.4 mm wide.

The stellate, dark reddish-brown apothecia distinguish this species from others in the genus Ionaspis.