[2] Nesolechia fungi typically develop gall-like structures on their hosts that may be roughly spherical to lobe-like or leafy.

[3] The genus was circumscribed in 1856 by Italian lichenologist Abramo Bartolommeo Massalongo, with Nesolechia oxyspora assigned as the type species.

He also included N. inquinans, N. thallicola, N. heeri, and N. punctum in the genus;[4] these are now placed in the genera Micarea, Phacopsis, Scutula, and Bachmanniomyces, respectively.

[5] In 2017, Divakar and colleagues used a then-recently developed "temporal phylogenetic" approach to identify temporal bands for specific taxonomic ranks in the family Parmeliaceae, suggesting that groups of species that diverged within the time window of 29.45–32.55 million years ago represent genera.

[7] As of July 2021[update], Species Fungorum accepts three species in Nesolechia:[8] Index Fungorum lists 62 taxa that have been named Nesolechia, but as Paul Diederich and colleagues explained in their 2018 review of lichenicolous fungi, "A high morphological plasticity, sometimes correlated with host selection, has led to the description of many poorly characterized taxa", and many of those published names are not accepted by taxonomic authorities,[3] or have been transferred to other genera.