Lambiella isidiata is a species of saxicolous (rock-dwelling) lichen in the family Xylographaceae. Found in Venezuela, it was formally described as a new species in 2015 by Dutch lichenologist André Aptroot. The type specimen was collected from the Sierra Nevada de Santo Domingo (Merida) at an altitude of 3500m (11,500feet), where it was found growing on siliceous rock. The species differs from other Lambiella species, as well as Rimularia species (a similar genus), in its long, slender, and sometimes branched isidia.