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.

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

Southwest of San Quintín in the Punta Mazo Reserve (managed by Terra Peninsular), on E side of Bahía Falsa in shoreline boulder outcrops. Leavitt et al. 16-863, Dec 2016

Southwest of San Quintín in the Punta Mazo Reserve (managed by Terra Peninsular), on E side of Bahía Falsa in shoreline boulder outcrops. Leavitt et al. 16-847, Dec 2016

Southwest of San Quintín in the Punta Mazo Reserve (managed by Terra Peninsular), on E side of Bahía Falsa in shoreline boulder outcrops. Leavitt et al. 16-857, Dec 2016

Morro Bay, CA, Hale 33688,
July 1965, holotype

San Cruz Island, CA
Bratt 4475

Bahía de San Quintín, BCN,
Spjut 9329D, May 1986 (scanned
from a black & white photocopy of specimen at US)

Los Angeles Co., Palo Verdes, CA
Darrow 314 (COLO)

San Clemente Island, CA
Murbarger 151 (COLO)

Santa Cruz Island, CA
Schuster 15a (COLO)

+

Santa Barbara Island, CA
Bratt 3712

San Luis Obispo Co., CA
Riefner 86-25 (COLO, p.p., mixed
with Vermilacinia laeviagata)

     Niebla cornea is a lichen occurring mostly in California along the Pacific Coast south of San Francisco on the mainland and in the Channel Islands.  It is occasionally found  at scattered locations further south into Baja California as far south as near Punta Santa Rosalillita. The species is recognized by the flat ribbon-like branches—that unlike most other species of Niebla—hardly twist.  This is generally evident by the cortical ridges that define the primary branch margins ± in the same plane. The primary branches frequently dilate and digitately divide near apex into short to long terminal flattened branchlets.  The cortex is ± smooth and glossy, appearing stretched in some thalli to the extent that varicose-like ribs become apparent.  Another distinctive feature of Niebla cornea is the development of cup-like (cupular) apothecia in small aggregates near ends of branchlets, often in 4's. 

     Niebla cornea is most similar to N. eburnea, especially the type specimens, which are from relatively distant locations, Cerro Solo (BCN) and Morro Bay (CA).  Niebla eburnea is generally distinguished by the primary branches half-twisted near base and again near apex, by narrower terminal branchlets, by having a paler cream-like cortex (rarely dark green), by the presence of the lichen substance divaricatic acid (as opposed to sekikaic acid in N. cornea), and by the solitary disciform apothecia that form terminally, or develop on short subterminal branchlets.  The epithets for both species were chosen for their distinct but similar cortical features.

     Niebla cornea may be confused with Vermilacinia laevigata.  Vermilacinia laevigata often has terminal apothecia, in contrast to N. cornea apothecia positioned just below the apex near the branch margin often on a short lobe extension. Another similar species, V. johncassadyi, differs in having spreading recurved branches with apothecia that apparently abort development in terminal aggregates and below along branch margins. It also lacks medullary chondroid strands and depsides that characterizes Niebla.

       Niebla cornea might also be confused with N. homalea, which differs by the narrower branches that twist from base to apex, and which have transverse cracks developing at frequent intervals, and by the lichen substance of divaricatic acid. 

     Specimens of N. cornea collected by Charis Bratt (3712) from Santa Barbara Island and Riefner (86-25) from Morro Bay differ in having marginal and intermarginal cortical ridges densely covered by pycnidia and/or nodular apothecia.  They are remarkably similar for being collected at disjunct locations.  They appear related to N. lobulata by the lobulate margins, wavy cortical ridges, and by the irregular presence of fringed branchlets. They also appear related to N. dissecta by the thicker cortex and sinuous cortical  ridges, and to a specimen of a divaricatic-acid species, N. laminaria, collected from Pt. Loma in San Diego Co. (Bratt 5631), which has a thallus divided into short rounded lobes that are also similar to the Riefner specimen (86-25) except for spine-like segments.  Niebla images on the Internet shown from the Santa Monica Mts., Mt. Conejo (Hollinger 2011-10-19) with longer narrower branches are also similar in the wrinkled  cortical surface; their chemistry is not known but from all appearances they probably belong to N. lobulata, which has not been reported from California.

     Niebla dissecta differs from N. cornea by its 3–4 longitudinally ribbed branchlets, and by the thallus spreading more at the base than in height. This is in further contrast to the long sublinear branches of  N. disrupta.  The relationships of N. cornea 'variants' are shown in the following dendrogram in comparison with N. dissecta and its variants.