Niebla (lichen)

''Niebla'', also known as the sea-fog lichens, is a genus of yellow-green fruticose lichens that grow on rocks, trees, and shrubs within the fog zone of coastal North America,Brodo, I. M., S. D. Sharnoff, and S. Sharnoff. 2001. Lichens of North America. Yale University Press: New Haven. or more narrowly defined to occur on rocks and soil along the Pacific Coast from Mendocino County in California south to Baja California Sur.Spjut, R. W. 1996. ''Niebla'' and ''Vermilacinia'' (Ramalinaceae) from California and Baja California. Sida Miscellany 14, pp. 1-208. Botanical Research Institute of Texas, Inc., Fort Worth.

Taxonomy

The genus name is a substitute nameRundel, P.W. and P.A. Bowler, 1978. ''Niebla'', a new generic name for ''Desmazieria'' (Ramalinaceae). Mycotaxon 6: 497–499 for ''Desmazieria'', a homonym created by Camille Montagne in 1852 who recognized only one species in the genus (''D. homalea''); however, the name ''Desmazeria'', although not spelled exactly the same but nevertheless considered to be the same (homonym), had been given to a genus of grass (Poaceae) by Barthélemy Dumortier in 1822. The earliest name is the one that must be retained unless the later name is conserved, according to the International Code of Botanical Nomenclature. Additionally, the type species name for ''Niebla'' is ''Niebla homalea'', based on the name given to the one species that had been recognized by Montagne for the genus, not ''Niebla ceruchis''.Sérusiaux, E., P. van den Boom, and D. Ertz. 2010. A two-gene phylogeny shows the lichen genus ''Niebla'' (Lecanorales) is endemic to the New World and does not occur in Macaronesia nor in the Mediterranean basin. Fungal Biology 114: 528–37.

The genus ''Niebla'' has also been interpreted broadly to include the genus ''Vermilacinia'',Bowler, P. and J. Marsh. 2004. ''Niebla''. ‘Lichen Flora of the Greater Sonoran Desert 2’: 368–380 although both classifications distinguish species by the presence or absence of chondroid strands. In the broad classification, only three species of ''Niebla'' with chondroid strands are recognized under two arbitrary groups of lichen substances based on their reaction to chemical spot tests of which the most useful in ''Niebla'' appears to be ''para''-phenylenediamine (pd); the nine species in the narrow classification that contain depsidones (pd+) are all placed under ''N. josecuervoi'' in the broad classification. A second group that contains depsides but also includes the acid-deficient chemotype (''N. homaleoides''), collectively treats 32 species under the name ''N. homalea''. The inclusion of the acid-deficient species in ''N. homalea'' disregards the chemotaxonomic attribute of a pigment associated with species that contain salazinic acid. Both classifications recognize ''N. isidiaescens''. Eleven other species that are treated in ''Vermilacinia'' are distinguished by thallus morphology.

Molecular studies on the North American species of ''Niebla'' and ''Vermilacinia'' have been limited and contradictory. An unpublished study mentioned in a 1995 communication indicated that ''Niebla'' was paraphyletic and that by recognizing ''Vermilacinia'' rendered ''Niebla'' monophyletic. A later study—that reported largely on Old World species of ''Ramalina'' and which included collections of ''Niebla'' and ''Vermilacinia'' species—concluded that ''Niebla'' was monophyletic. However, source material (voucher specimens) cited in the later study for the basis of the DNA analysis of ''Niebla'' was reported to be from California and identified ''N. homalea'' with protocetraric acid and triterpenes. But this chemotype had not been known in ''Niebla'', nor are depsidones known to be present in ''N. homalea'', nor are they present in any species of ''Niebla'' in California; protocetraric acid is found only in ''N. pulchribarbara'', which lacks triterpenes, a rare species that occurs in northern Baja California. In the ''Lichen Flora of the Greater Sonoran Desert Region'', the description given for ''N. homalea'' erroneously described the species to have depsidones, including protocetraric acid, which may be confused with salazinic acid when conducting thin-layer chromatography. Salazinic acid is a common lichen substance accessory to triterpenes in species of ''Vermilacinia'', while it may also be noted that the morphology of ''V. laevigata'' is easily confused with that of ''N. homalea''.

In view of the controversial classification of this ''Ramalina'' complex of genera, and that many of the species are common along the Pacific coast of North America, it may be helpful to conservationists to have molecular studies be conducted to correlate the different views of the species concepts with their DNA, which should include representative specimens from the entire geographic range of the species before drawing definitive conclusions about their synonymy.

Description

''Niebla'' has 42 species distinguished by secondary metabolites (lichen substances) and by morphology. ''Niebla'' lichen substances fall into two groups. One group has triterpenes, the other lacks triterpenes. Species of ''Niebla'' that contain triterpenes also contain depsides as major lichen substances, which in a species may be either divaricatic acid or sekikaic acid. The group lacking triterpenes contains depsidones as major lichen substances—protocetraric acid, hyprotocetraric acid, salazinic acid, or none of the acids are present in ''N. homaleoides''. Usnic acid, pigments, and other unknown secondary substances are also produced but have little taxonomic value except for one pigment associated with species that produce salazinic acid. The same pigment occurs in the acid-deficient ''N. homaleoides''.

The morphological characters employed to distinguish species of ''Niebla'' include the orientation of ridges in the lichen cortex, differences in fragmentation branchlets, which often have black carbonized pycnidia, and the development of specialized asexual propagules referred to as soredia and isidia. Most species occur in Baja California, Mexico.

''Niebla'' is related to ''Ramalina'' and ''Vermilacinia'', distinguished from them by the presence of thread-like hyphae intertwined into gelatinized cords called chondroid strands. These strands run lengthwise within the central axis (medulla) of the ''Niebla'' thallus, and are visible to the naked eye when a branch of the thallus is sliced or torn. Chondroid strands also protrude into the cortical surface in various network arrangements in which species are recognized by their particular network structure.

Some ''Ramalina'' species in the Mediterranean Region have medullary chondroid stands unattached to the medulla; however, they differ from ''Niebla'' in having pale pycnidia instead of black pycnidia, and often contain pseudocyphellae and more than one depside or depsidone accompanied by triterpenes and/or bourgeanic acid. Their classification in ''Ramalina'' is supported by molecular phylogeny data.

''Vermilacinia'' differs from both ''Ramalina'' and ''Niebla'' by the absence of chrondroid strands, and by presence of other lichens substances, predominantly terpenes that differ from those in ''Niebla''. Of taxonomic significance is the diterpene (-)-16 α-hydroxykaurane, a rare secondary metabolite in lichens. This diterpene is found only in ''Vermilacinia'' within the Ramalinaceae, and also in ''Roccella'' (Roccellaceae).

Species

The following lists all the species in the genus ''Niebla'' that have been recognized. In bold are those generally accepted. Listed separately are those also treated in the genus ''Vermilacinia''. Species rare or isolated in occurrence are also noted.

*'' Niebla arenaria''
*'' Niebla brachyura'' Rare
*'' Niebla caespitosa''
*'' Niebla contorta''
*'' Niebla cornea''
*'' Niebla dactylifera'' Rare
*'' Niebla dilatata''
*'' Niebla disrupta''
*'' Niebla dissecta''
*'' Niebla eburnea''
*'' Niebla effusa''
*'' Niebla fimbriata''
*'' Niebla flabellata''
*'' Niebla flagelliforma''
*'' Niebla halei'' Rare
*'' Niebla homalea''
*'' Niebla homaleoides'' Rare
*'' Niebla infundibula'' Rare
*'' Niebla isidiaescens''
*'' Niebla isidiosa'' Rare
*'' Niebla josecuervoi''
*'' Niebla juncosa'' var. ''juncosa''
*'' Niebla juncosa'' var. ''spinulifera''
*'' Niebla laminaria''
*'' Niebla limicola''
*'' Niebla lobulata''
*'' Niebla marinii''
*'' Niebla palmeri'' Rare
*'' Niebla podetiaforma''
*'' Niebla pulchribarbara'' Rare
*'' Niebla ramosissima'' Rare
*'' Niebla rugosa''
*'' Niebla siphonoloba''
*'' Niebla sorediata'' Rare
*'' Niebla sorocarpia''
*'' Niebla spatulata'' Rare
*'' Niebla suffnessii''
*'' Niebla tesselata'' Rare
*'' Niebla testudinaria''
*'' Niebla turgida''
*'' Niebla undulata''
*'' Niebla usneoides''
*'' Niebla versiforma'' Rare

Species classified in ''Niebla'' also recognized in Vermilacinia

*'' Niebla cephalota''
*'' Niebla ceruchis''
*'' Niebla cedrosensis''
*'' Niebla ceruchoides''
*'' Niebla combeoides''
*'' Niebla flaccescens''
*'' Niebla granulans''Sipman, H.J.M. 2011. New and notable species of ''Enterographa'', ''Niebla'', and ''Sclerophyton s. lat.'' from coastal Chile. Bibliotheca Lichenologica 106: 297-308.
*'' Niebla laevigata''
*'' Niebla polymorpha''
*'' Niebla procera''
*'' Niebla robusta''
*'' Niebla tigrina''
*''Niebla tuberculata'' Rare

References

External links

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Information on ''Vermilacinia'' subgenus ''Vermilacin''

{{Authority control

Lecanorales genera
Ramalinaceae
Lichen genera
Taxa described in 1978
Fungi of California