Niebla eburnea

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

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.

 

eburnea-10234.jpg (84957 bytes)

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

eburnea-9047E.jpg (42727 bytes)

Cerro Solo, BCN, Spjut &
Marin 9047
, May 1985, isotype


eburnea-9888B.jpg (141080 bytes)

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

Pt Lobos St Park
Monterrey Co., CA
image, Chris Parrish 69357
no chemical data

Above Point Pedernales, CA
Bratt 5589

Pt Lobos St Park
Monterrey Co., CA
image, Chris Parrish 69359
no chemical data

 

     Niebla eburnea is a common 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 rock 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 distribution of types by the Smithsonian Institution (to BCMEX, LA). 

     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) in between, 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).

     Niebla eburnea at the type location resembles N. cornea (sekikaic acid) at Morro Bay (type) in having mostly simple, apical dilated branches that are also uniformly blackened around base (from pigment skyrin).   The two species are best separated by chemistry, although N. cornea may be recognized by the small clusters of cupular apothecia, usually four in number near branch apex, in contrast to solitary, lenticular apothecia in N. eburnea, or more numerous apothecia on nodular branchlets along lower branch margins, or apothecia sometimes terminally aggregate.  It is interesting to note that Vermilacinia laevigata, which can be easily confused with these species, also occurs with both species further north along the Pacific Coast to Marin Co., California. Vermilacinia laevigata is easily distinguished by its lichen substances (zeorin, [-]-16 α-hydroxykaurane), and by the absence of chondroid strands in the medulla.

     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; Curtis Björk photo from Jughandle State Preserve in Mendocino Co. 7-9-2011), but are referred to N. eburnea by the branches appearing thicker along margins and near apex, in contrast to ± thinner acute margins of N. homalea.  Other larger more openly branched thalli are recognized by the branch margins remaining in the same plane; i.e., by not twisting (e.g., Curtis Björk photo from Jughandle State Preserve, 7-9-2011).  Terminal branch segments of N. eburnea often appear lobulate; the lobules thicker much like soralia as seen in species of Parmotrema, or occasionally densely lined with immature apothecia (Chris Parrish, Pt Lobos St Park, Sea Lion Pt; 2011-5-19).

     Another related species, N. testudinaria, differs by the regular appearance of reticulate cortical ridges in which the branches appear 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.  Their differences are summarized in the following table, the bold type indicating the diagnostic features.

 

 

N. homalea

N. eburnea

N. testudinaria

 

 

 

 

Branching general

Anisotomic.

Anisotomic.

Isotomic.

Terminal bifurcate
branches

Usually not evident.

Usually not evident.

Frequent.

Branch shape lengthwise

Sublinear.

Variable.

Variable.

Branch shape cross-section

Elliptic.

Elliptic.

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.

Variable.

Cortex

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.

Apothecia

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.