Niebla eburnea

©The World Botanical Associates Web Page
Prepared by Richard W. Spjut
April 2003, Oct. 2005, Sep 2012, Sep 2021,
Dec 2021, Aug 2022

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
, Ramalina and Vermilacinia
Emmanuel Sérusiaux & Richard  Spjut
Baja California, Jan-Feb 2016

Spjut R, Simon A, Guissard M, Magain N, Sérusiaux E. 2020. The fruticose genera in the Ramalinaceae (Ascomycota, Lecanoromycetes): their diversity and evolutionary history.  MycoKeys. 73: 1–68. published online.
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. DOI: 10.22541/au.161766187.74749853/v1

Additional Discussion and References: See: Introduction to Niebla and its phylogeography


Bahía de San Quintín,
Spjut & Sérusiaux 17044, Jan 2016. DNA 4688

Monterey County,
Pt Lobos
Spjut 17811, July 2017

Marin County,
South of Stinson Beach,
Spjut 17805, July 2017

Bahía de San Quintín,
Spjut & Sérusiaux 17055B, Jan 2016. DNA 5055. TLC: Divaricatic acid with salazinic acid, and triterpenes. 


TLC profile for selected species of Niebla received from Dr. Harinantenaina Liva Romuald Rakotondraibe at the Ohio State University, Oct 2017. Niebla eburnea L2 (17805) and L10 (17811). N. eburnea from the Monterey Peninsula (L10) shows two sky blue spots for Godin Reagent absent in the N. homalea and the other N. eburnea specimen from Stinson Beach, Marin Co. This may be due to differences in triterpenoids. Divaricatic acid shown for both specimens. N. disrupta was reidentified N. homalea based on TLC.

Niebla eburnea ITS and six loci phylogenetic trees in part showing two separate clades with N. homalea in California and in Baja California. Baja specimens collected near Bahía Falsa west of San Quintín. California specimens shown above associated with N. homalea, 17811 from the Monterey Peninsula most closely related to 17805 on the Pt. Reyes Peninsula south of Stinson Beach. 

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Bahía de San Quintín,
Spjut 10234, Mar 1988

eburnea-11386.jpg (79624 bytes)

San José Ranch between Punta Canoas and Punta Blanca,
Spjut & Marin 11386, Apr 1990

eburnea-13016.jpg (37787 bytes)

Puerto Catarina, Spjut
 & Marin 13016
, Apr 1994

eburnea-13034.jpg (157403 bytes)

Puerto Catarina, Spjut
& Marin 13034
, Apr 1994

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Cerro Solo, BCN, Spjut &
Marin 9047
, May 1985, isotype.
Slightly active against MCF7 (hormone dependent breast cancer). NMR of the extract showed isodivaricatic acid instead of divaricatic acid. Other unknowns present.

eburnea-9888B.jpg (141080 bytes)

San Andrés Ranch,
~100 km N of Guerrero Negro, Spjut & Marin 9888B, May 1985


Above Point Pedernales, CA
Bratt 5589



     Niebla eburnea is a common fruticose lichen on rocks along the California coast from Mendocino Co. to San Diego Co., occurring also in the Channel Islands, and less frequently further south in Baja California to near Punta Santa Rosalillita.  The original (type) collection was from a rock outcrop within ocean mist near Cerro Solo along the Pacific Coast of Baja California between San Vicente and Colonet.  It was part of sample submitted for anti-HIV screening that was collected on the vertical face of a isolated 1.5 tall rock on a beach in association with other fog lichens, N. josecuervoi, Vermilacinia laevigata, V. ceruchoides, and V. procera.  Duplicates were later provided to the Lichen Exchange at ASU, in addition to isotypes that may have been distributed by the Smithsonian Institution (intended for BCMEX, LA).  The type collection was reported to have divaricatic acid but later found to actually have isodivaricatic acid as determined by a natural product chemist at Ohio State University (Professor Rakotondraibe) employing NMR.  

     Niebla eburnea is identified by the ± creamy (ivory)-glazed cortex (skin-like or like frosting on a pastry), by its branches half-twisted near apex and near base—in which the margins ± do not alternate (cross or unite), by the terminal part of a main branch often digitately divided into finger-like or claw-like branchlets (fringing branchlets), and by the key lichen substance, divaricatic acid (with triterpenes and basal pigment skyrin), or isodivaricatic acid from the type collection collected just west of Cerro Solo, Baja California in May 1985.

     The type for Niebla eburnea was collected near Colonet, BC. It resembles the type for  N. cornea (sekikaic acid) from Morro Bay in having mostly simple, apical dilated branches uniformly blackened around base (from pigment skyrin).   The two species are distinguished by their chemistry.  Vermilacinia laevigata can be easily confused with these species.  It differs by the absence of chondroid strands, and by the terpenes  zeorin (triterpene) and [-]-16 α-hydroxykaurane (diterpene); N. eburnea has triterpenes nieblastictanes and nieblaflavicanes.

     Occasionally N. eburnea is difficult to distinguish from N. homalea (divaricatic acid) and N. disrupta (sekikaic acid), which generally have narrower branches that twist 90° at frequent intervals between the base and apex, and which have a uniformly glossy cortex transversely cracked at various intervals.  Problem thalli have ±uniformly narrow branches with a transversely cracked cortex (e.g., Bratt 5591 from Point Pedernales, CA, photo 10.3, Spjut 1996). DNA phylogeny shows these in sister clades with N. homalea cryptic species, and also N. testudinarai; thus, phylogenetically unresolved based on phenotypic identifications.

     The phylogeny for N. eburnea in Spjut et al. (2020) included four specimens from three locations, two in northern California (Monterey Peninsula , Pt. Reyes) and one in Baja California near San Quintín for two specimens.  Analyses by BPP and Stacey both delimited three species that likely correspond to three clades. In the phylogenetic tree (Fig. 7), the species in Baja California is monophyletic. In California, the species is not  separated from N. homalea in which both occur together in two separate clades. Thus, in northern California both N. homalea and N. eburnea comprise cryptic species, while N. eburnea may also be viewed as a cryptic hybrid (or allasomorph), phenotypically different but genetically undifferentiated from N. homalea.

     As noted above, the type collection reportedly contains only isodivaricatic acid (Professor Rakotondraibe, pers. comm.), in contrast to divaricatic acid confirmed for specimens collected of N. homalea at the putative type locality at Pt. Reyes (Zhang et al. 2020).  Whether cryptic species relate to differences in isomers remains to be determined while it may be further noted that they can have different physical properties; for example, isodivaricatic acid has shown activity against a cancer cell line, but not divaricatic acid, although reported in literature to have antifungal and antibacterial activities.

      The related N. testudinaria differs by the regular appearance of reticulate cortical ridges resulting in the branches appearing more prismatic than sub-tubular; it occurs from California to Baja California Norte, especially in the Channel Islands, and is also on Isla Guadalupe and on Isla San Martín.  Niebla testudinaria was found in a separate clade from N. eburnea, but not from N. homalea (Spjut et al. Fig. 7). Their differences are summarized in the following table, the bold type indicating the diagnostic features.



N. homalea

N. eburnea

N. testudinaria





Branching general




Terminal bifurcate

Usually not evident.

Usually not evident.


Branch shape lengthwise




Branch shape cross-section



Elliptic, prismatic, or ±4-angled.

Branches twist

Frequent between base and apex.

Half twist near base and apex.

Frequent between base and apex.

Branch margin

Usually well-defined,  acute.

Rounded to acute, usually thickened, wrinkled in upper half of thallus.



Glassy, transversely cracked at various intervals.

Creamy frosting or like a glazed donut, irregularly transversely cracked or pleated.

Dull, transversely cracked and reticulate ribbed between margins.


Subterminal on short branch-like segments, often perpendicular to branch margin.

Usually subterminal, often in plane with the branch.

Usually absent, subterminal in type,  elevated from main branch by a short flattened lobe.

     Niebla eburnea includes variation that might be recognized as distinct varieties but here considered 'variants' as outlined below with reference to geographic locations from where specimens were collected.