Vermilacinia rigida is a dark green, rare fruticose lichen that occurs in fog areas along the Pacific Coast of Baja California, known only from two locations about 100 km north of Guerrero Negro.

Vermilacinia rigida is classified in the subgenus Vermilacina in which it is distinguished by the thallus divided into short rigid erect branches blackened to about ¼ the way up from the base.

[1] Vermilacinia rigida—easily recognized at a glance—is most similar in morphology to V. laevigata, a species that is twice its size and often less definite in its shape of the branches, irregularly widened in areas to as much as 3.5 cm across.

Vermilacinia laevigata also differs in its chemistry, lichen substances include the T3 compound, bourgeanic acid, and zeorin that are consistently present.

This particular ridge was observed during May 1985 by Spjut—while he and Marin were collecting samples of lichens in search of new drugs to treat HIV—to have fog lingering around the peaks most of the day[1]).