Ionaspis is a genus of lichen-forming fungi in the family Hymeneliaceae. It contains six species of saxicolous (rock-dwelling), crustose lichens. The genus was originally circumscribed in 1871 by Theodor Magnus Fries. He segregated the genus from Aspicilia based on the presence of Trentepohlia rather than Trebouxia as the partner.
, Species Fungorum (in the Catalogue of Life) accepts 6 species of Ionaspis: