The epithet vainioi honours lichenologist Edvard Vainio (1853–1929), who did pioneering work on the Brazilian lichens.

[1] The crust-like thallus of Lecanora vainioi ranges in colour from yellowish-white to very pale yellowish grey.

The areolae are initially tightly attached (adnate) and cushion-shaped (pulvinate), but later merge so that the crust surface becomes irregularly wrinkled (verrucose) and partly rimose (containing clefts, cracks, or fissures).

[1] Secondary chemicals produced by the lichen include atranorin, epinorin, and zeorin.

It prefers habitats that are near humid coasts, as well as woodland savannah in drier inland regions.