Niebla and Vermilacinia (Ramalinaceae) from California and Baja California.  
Spjut, R.W., 1996. ISSN 0833-1475, 208 pp.  
Sida, Botanical Miscellany 14. Botanical Research Institute of Texas, Inc.

Evolutionary history of coastal species of fog lichen genera
Niebla, Ramalina and Vermilacinia
Emmanuel Sérusiaux & Richard  Spjut
Baja California, Jan-Feb 2016

Spjut R, Simon A, Guissard M, Magain N, Sérusiaux E. The fruticose genera in the Ramalinaceae (Ascomycota, Lecanoromycetes): their diversity and evolutionary history.  MycoKeys. 2020 Oct 30;74:109-110]. MycoKeys. 2020;73:1-68. Published 2020 Sep 11. doi:10.3897/mycokeys.73.47287

Evolution and diversification of Niebla
Steve Leavitt et al., Baja California, Dec 2016

Jorna J, J Linde, P Searle, A Jackson, M-E Nielsen, M Nate, N Saxton, F Grewe, M de los Angeles Herrera-Campos, R Spjut, H Wu, B Ho, S Leavitt, T Lumbsch.  Species boundaries in the messy middle -- testing the hypothesis of micro-endemism in a recently diverged lineage of coastal fog desert lichen fungi. Ecology and Evolution. Published Online: 20 Dec 2021.  https://onlinelibrary.wiley.com/doi/full/10.1002/ece3.8467.

Road to Punta Baja south of El Rosario; 30°00'075, 115°45.965, 140 m. Low  maritime scrub
      primarily with Ambrosia chenopodiifolia, Aesculus parryi, Euphorbia misera,
      Frankenia palmeri, Mammillaria dioica, Stenocereus. Sérusiaux 17084-4724, Jan 2016

South of El Rosario along road to Punta Baja, on sandy, wind-swept ridgeline. Leavitt et al. 16-1013, Dec 2016

Slopes above Puerto Catarina, Spjut & Marin 13023, Apr 1994

      Niebla undulata is a fruticose lichen often found on pebbles and boulders along beaches and on mesas in the Northern Vizcaíno Desert of Baja California, and also occurs on Santa Cruz Island in California.  It is identified by the lichen substance of divaricatic acid (with triterpenes), by the broad undulating contorted lobes arising from a shorter tubular basal branch, and by the cortical surface appearing smooth and recessed between the ridges.  The cortical ridges are oriented longitudinally near apex, which seems related to the twisted branches.  

     Its closest relative, Niebla podetiaforma, shares the character attributes of divaricatic acid and the small clumps of fistulose branches that arise from a pigmented holdfast, but differs in the  prominently and finely reticulate cortex in which the ridges are transversely oriented, and by the cortical surface appearing more inflated (bulging) between ridges.

     The undulate lobes and aggregate apothecia (when present) of N. undulata are seen in N. sorocarpia, distinguished by the larger thallus in which the tubular basal branches appear longer than the upper contorted branches.  Niebla lobulata, another similar species, differs in having sekikaic acid.

     Niebla undulata is variable in habit as shown above.  The branches may lie on the ground, or they may be erect, or they may spread at wide angles from the base.  They are often irregular in shape, but occasionally appear bladelike as seen above in the image Spjut & Marin 13047. 

     Species delimitation analyses of four specimens of Niebla undulata in Spjut et al (2020) indicated three species, presumably from three different locations.  The type was collected on coastal ridges between Punta Rocosa and Punta Negra.

Additional References: See Niebla.