Niebla homalea is a species of fruticose lichen that grows on rocks in foggy areas along the Pacific Coast of North America, from Mendocino County, California south to Bahía de San Quintín on the main peninsula of Baja California, with an isolated occurrence further south on vertical rock faces above Punta Camachos, and other occurrences in the Channel Islands and on Guadalupe Island.

[5] Niebla homalea, which is classified in the family Ramalinaceae, was originally describedin 1810 by Swedish botanist Erik Acharius as a species of Ramalina based on a specimen collected by Archibald Menzies on rocks around San Francisco.

[3] The interpretation of Ramalina ceruchis of South America—over time—was broadened to include morphological variants that grew on rocks, bushes and cactus spines; sometimes classified in other genera such as Evernia, Roccella, and Usnea[8] some recognized as different varieties and species.

A two-gene phylogeny shows the lichen genus Niebla (Lecanorales) is endemic to the New World and does not occur in Macaronesia nor in the Mediterranean basin.

Recall from above that the South American Ramalina ceruchis had also not been clearly defined prior to Montagne, and while the type specimen may not have been recognized to be most similar to species that grew on rocks than on bushes, the interpretation in North America was that the “Ceruchis Group” applied only to thalli that for those that grew on trees and shrubs, and this interpretation then extended to species in South America.

Added to this confusion are many studies that reported on lichen substances for species in the “Ceruchis Group” without a standard reference, the type specimen.

It was not until Spjut’s taxonomic revision of the genus that the types for the North American species were accounted for[3]Niebla had not been clearly defined at the time it was created.

Recall from above that the South American Ramalina ceruchis had also not been clearly defined prior to Montagne, and while the type specimen may not have been recognized to be most similar to species that grew on rocks than on bushes, the interpretation in North America was that the “Ceruchis Group” applied only to thalli that for those that grew on trees and shrubs, and this interpretation then extended to species in South America.

Added to this confusion are many studies that reported on lichen substances for species in the “Ceruchis Group” without a standard reference, the type specimen.