Niebla testudinaria is a fruticose lichen that grows on rocks along the foggy Pacific Coast of North America, from Marin County, California to just south of Tijuana in Baja California, in the Channel Islands (Santa Cruz Island) in California, and Isla San Martín and Guadalupe Island in Baja California The epithet, testudinaria given by William Nylander in 1870, is probably in reference to the dilated branch with a reticulated surface, similar to a tortoise shell.