''Niebla usneoides'' is a fruticose lichen that grows on rocks in the fog zone along the Pacific Coast of

Baja California Baja California (; 'Lower California'), officially the Free and Sovereign State of Baja California ( es, Estado Libre y Soberano de Baja California), is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mex ...

in the Vizcaíno Desert and Magadalena Desert regions, and reported also from the

Channel Islands The Channel Islands ( nrf, Îles d'la Manche; french: îles Anglo-Normandes or ''îles de la Manche'') are an archipelago in the English Channel, off the French coast of Normandy. They include two Crown Dependencies: the Bailiwick of Jersey, ...

and mainland of southern California.Spjut, R. W. 1996. ''Niebla'' and ''Vermilacinia'' (Ramalinaceae) from California and Baja California. Sida Bot. Misc. 14 The epithet, '' usneoides'' is in reference to the similarity to the lichen genus ''

Usnea ''Usnea'' is a genus of mostly pale grayish-green fruticose lichens that grow like leafless mini-shrubs or tassels anchored on bark or twigs.Field Guide to California Lichens, Stephen Sharnoff, Yale University Press, 2014, The genus is in the f ...

''.

Distinguishing features

''Niebla usneoides'' is distinguished by a

thallus Thallus (plural: thalli), from Latinized Greek (), meaning "a green shoot" or "twig", is the vegetative tissue of some organisms in diverse groups such as algae, fungi, some liverworts, lichens, and the Myxogastria. Many of these organisms wer ...

divided into numerous subtubular more or less linear shaped branches, to 4 cm high and 8 cm across, that are fringed above with spiculiform branchlets and by short coralloid isidia (

isidium An isidium is a vegetative reproductive structure present in some lichens. Isidia are outgrowths of the thallus surface, and are corticated (i.e., containing the outermost layer of the thallus), usually with a columnar structure, and consisting o ...

) along margins. The branches become terminally whip-like, or abruptly curved. Pycnidia and apothecia are absent. Similar species are '' Niebla suffnessii'' and ''

Niebla isidiaescens ''Niebla isidiaescens'' is a species of fruticose lichen in the family Ramalinaceae. It was originally described in 1994 from specimens collected in Baja California. The lichen grows on rocky outcrops in open maritime scrub habitats. Taxonom ...

''. ''Niebla suffnessii'' is viewed as the fertile counterpart of a species pair (''N. suffnessii'' and ''N. usneoides''). They appear to intergrade by isidia in rare thalli occurring sparsely at the base of the thallus of ''N. suffnessii''. ''Niebla isidiaescens'' differs in having divaricatic acid instead of sekikiaic acid and by the presence of pycnidia.

Taxonomic history

''Niebla usneoides'' was first recognized by Richard Spjut as distinct from other species in the genus while collecting samples for chemopreventive agents and for anticancer screening on the Vizcaíno Peninsula near Arroyo San Andrés in May 1986. A 700 gram sample of ''N. usneoides '' was collected in a mixed desert and

coastal sage scrub Coastal sage scrub, also known as coastal scrub, CSS, or soft chaparral, is a low scrubland plant community of the California coastal sage and chaparral subecoregion, found in coastal California and northwestern coastal Baja California. It is w ...

region characterized by '' Pachycormus discolor'', ''

Encelia ''Encelia'' is a genus of the plant family Asteraceae. It consists of shrubs (and one geophyte) of arid environments in southwestern North America and western South America. All have n = 18 chromosomes. All the North American species are obliga ...

stenophylla'', '' Eriogonum encelioides'', ''Eriogonum pondii'', ''

Salvia cedrosensis ''Salvia cedrosensis'', commonly known as the Cedros Sage or Cedros Island Sage is an evergreen fruticose perennial plant that is endemic to the western (Pacific) coast of Baja California in Mexico, native to the Vizcaino peninsula and Cedros Is ...

'', '' Petalonyx linearis'', ''Rhus lentii'' and various lichens and one desert mushroom '' Battarraea phalloides''. The species (''N. usneoides'') was also found growing with '' Niebla lobulata'', and '' Niebla suffnessii'', both also contain sekikaic acid but differ in the absences of isidia (

). ''Niebla usneoides'' has been included under ''

'' on the assumption that differences in the secondary metabolites, sekikaic acid and divaricatic acid, represent different “races” of one species, derived from a highly variable '' Niebla homalea''.Bowler, P. and J. Marsh. 2004. ''Niebla''. ‘Lichen Flora of the Greater Sonoran Desert 2’: 368–380.Bowler, P. A., R. E. Riefner, Jr., P. W. Rundel, J. Marsh & T.H. Nash, III. 1994. New species of ''Niebla'' (Ramalinaceae) from western North America. Phytologia 77: 23–37. However, the term race implies a genetic difference derived from sexually reproducing species. Both ''N. isidiaescens'' and ''N. usneoides'' reproduce primarily by asexual propagules; thus, they can hardly be considered races of an asexually reproducing species (''N. isidiaescens'') as treated by Peter Bowler and collaborators. The two chemotypes (sekikiaic aicd, divaricatic acid) generally do not occur together, or if found in the same region, usually one chemotype is dominant such as reported by Spjut for ''N. usneoides''. This may be viewed as evidence of a genetic difference as opposed to environmentally induced chemical variation. Alternatively, the two isidiate species are races of the fertile (sexual) species, which under a very broad species concept is ''N. homalea'', and if this view is adopted, then both isidiate species would be included under ''N. homalea''.

Notes

References

External links

World Botanical Associates, ''Niebla isidiaescens'', retrieved 11 Jan 2015
{{Taxonbar, from=Q20720467 Lichen species Lichens of North America Ramalinaceae Lichens described in 1996 Taxa named by Richard Wayne Spjut