# Psiloparmelia

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***Psiloparmelia*** is a [genus](/source/Genus) of [lichen](/source/Lichen) belonging to the family [Parmeliaceae](/source/Parmeliaceae). It contains 13 Southern Hemisphere species, most of which are found [growing on rocks](/source/Saxicolous_lichen) at high elevations in South America. There are several characteristic features of the genus that are used to distinguish it from the [morphologically](/source/Morphology_(biology)) similar genera, such as *[Arctoparmelia](/source/Arctoparmelia)*, *[Flavoparmelia](/source/Flavoparmelia)*, and *[Xanthoparmelia](/source/Xanthoparmelia)*. These include a dark, velvety lower [thallus](/source/Thallus) surface that usually lacks [rhizines](/source/Rhizine), a negative test for [lichenan](/source/Lichenan), and a high concentration of [usnic acid](/source/Usnic_acid) and [atranorin](/source/Atranorin) in the [cortex](/source/Cortex_(botany)).

## Taxonomy

*Psiloparmelia* was [circumscribed](/source/Circumscription_(taxonomy)) by [Mason Hale](/source/Mason_Hale) in 1989 with two species: *[Psiloparmelia arhizinosa](/source/Psiloparmelia_arhizinosa)*, and the [type species](/source/Type_species), *[Psiloparmelia distincta](/source/Psiloparmelia_distincta)*. Hale had previously placed this [taxon](/source/Taxon) (as *Parmelia distincta*) in the genus *[Xanthoparmelia](/source/Xanthoparmelia)*. He also considered placement in *[Arctoparmelia](/source/Arctoparmelia)* due to similarities in lobe configuration, cortical chemistry, and the presence of a velvety lower surface. However, other differing characteristics precluded this classification, including a complete lack of [rhizines](/source/Rhizine) and the presence of [isolichenan](/source/Isolichenan) in the [cell walls](/source/Cell_wall). Hales' subsequent discovery of a species similar to *P. distincta* in [Lesotho](/source/Lesotho) convinced him that these two species were sufficiently distinct from both *Arctoparmelia* and *Xanthoparmelia* to warrant the creation of a new genus, *Psiloparmelia*, to contain them. Some taxonomic inspiration was drawn from [Vilmos Gyelnik](/source/Vilmos_Gyelnik)'s *Parmelia* sect. *Xanthoparmelia* subsect. *Endocoerulea*, which he created in 1931;[1] it was in this [subsection](/source/Section_(biology)) that *Parmelia distincta* was originally classified.[2] [Scanning electron microscopy](/source/Scanning_electron_microscopy) was used in a 1992 study to evaluate the structure of the epicortex in *Psiloparmelia*, revealing the presence of a rudimentary pored epicortex, which established another [character](/source/Phenotypic_trait) of the genus.[3]

Nine newly [described](/source/Species_description) species and one [new combination](/source/New_combination) were added to the genus in 1992 by John Elix and Tom Nash, who published a synopsis of the genus.[4] In 2006, [molecular](/source/Molecular_phylogenetics) data supported the transfer of *Xanthoparmelia peruviensis* to *Psiloparmelia*, despite it not sharing all the [morphological](/source/Morphology_(biology)) features characteristic of other species in the genus, particularly in having a densely rhizinate lower surface.[5]

## Description

*Psiloparmelia* species are [foliose](/source/Foliose_lichen) lichens growing on rocks, to which they can be tightly or loosely attached, depending on the species. The [thallus](/source/Thallus), which reaches a diameter of 3–14 cm (1.2–5.5 in), is made of irregularly shaped lobes whose margins lack [cilia](/source/Cilia).[4] The upper cortex of *Psiloparmelia* is a palisade [plectenchyma](/source/Plectenchyma) – comprising [hyphae](/source/Hypha) arranged perpendicular to the surface. It is partly covered by a rudimentary epicortex (a thin homogeneous [polysaccharide](/source/Polysaccharide) layer on the surface of the cortex) with pores.[3] The texture of the upper cortex ranges from smooth to wrinkled, and it is [pruinose](/source/Pruinose). [Pustules](/source/Pustule) and [soredia](/source/Soredia) may be present or absent, depending on the species, while [pseudocyphellae](/source/Pseudocyphella) and [isidia](/source/Isidia) are always absent. The [cell walls](/source/Cell_wall) contain the [alpha glucan](/source/Alpha_glucan) molecule [isolichenan](/source/Isolichenan). [Green algae](/source/Green_algae) are the [photobiont](/source/Photobiont) partner in *Psiloparmelia*.[4]

The lower surface of the thallus is black and velvety. It is covered with tiny bumps (minutely papillate), and usually lacks [rhizines](/source/Rhizine). Most species have an even finer velvety zone around the margin that is yellowish-grey or mouse-grey. The [apothecia](/source/Apothecia) are either attached directly to the thallus surface (adnate), or are mounted on a small stalk (substipitate); they measure 2–5 mm in diameter. The [ascospores](/source/Ascospore), which number eight per [ascus](/source/Ascus), have a spherical to elliptical shape, and measure 9–12 by 5–9 [μm](/source/Micrometre).[4]

*Psiloparmelia* has a relatively diverse [secondary chemistry](/source/Secondary_metabolite). Metabolites that have been recorded from the genus include [usnic acid](/source/Usnic_acid), [atranorin](/source/Atranorin), and the following [β-orcinol](/source/Orcinol) derivatives: [constipatic acid](/source/Constipatic_acid), [protoconstipatic acid](/source/Protoconstipatic_acid), [diffractiac acid](/source/Diffractiac_acid), [fumarprotocetraric acid](/source/Fumarprotocetraric_acid), [hypostictic acid](/source/Hypostictic_acid), [4-O-methylhypoprotocetraric acid](/source/4-O-methylhypoprotocetraric_acid), [isousnic acid](/source/Isousnic_acid), [norstictic acid](/source/Norstictic_acid), and [salazinic acid](/source/Salazinic_acid). There are several other lichen acids that are found in trace amounts. The presence of these lichens compounds helps to distinguish between morphologically similar species in the genus.[4]

## Habitat and distribution

*Psiloparmelia* is a genus of [saxicolous lichens](/source/Saxicolous_lichen), although *Psiloparmelia distincta* was recently recorded growing on old bones, the first reported time on that substrate.[6] The genus has a Southern Hemisphere distribution, with most of the species located in South America. Twelve of the thirteen species in the genus are found in high altitudes on the [Andes Mountains](/source/Andes_Mountains), ranging from Ecuador and Peru south to Bolivia and northern Argentina. They are typically the most common saxicolous foliose lichens that are collected in these locales. *Psiloparmelia arhizinosa* is the only species to break this distributional pattern; it is found at [alpine](/source/Alpine_climate) habitats at high elevations 3,000–3,300 ft (910–1,010 m) in Lesotho.[4]

## Species

- *[Psiloparmelia arhizinosa](/source/Psiloparmelia_arhizinosa)* Hale (1989) – Lesotho
- *[Psiloparmelia denotata](/source/Psiloparmelia_denotata)* Elix & T.H.Nash (1992) – Argentina; Peru
- *[Psiloparmelia dichotoma](/source/Psiloparmelia_dichotoma)* Elix & T.H.Nash (1992) – Peru
- *[Psiloparmelia diffractaica](/source/Psiloparmelia_diffractaica)* Elix & T.H.Nash (1992) – Argentina
- *[Psiloparmelia distincta](/source/Psiloparmelia_distincta)* (Nyl.) Hale (1989) – Argentina; Bolivia; Chile; Ecuador; Peru
- *[Psiloparmelia flavobrunnea](/source/Psiloparmelia_flavobrunnea)* (Müll.Arg.) Elix & T.H.Nash (1992) – Argentina; Bolivia; Chile; Ecuador; Peru
- *[Psiloparmelia hypostictica](/source/Psiloparmelia_hypostictica)* Elix & T.H.Nash (1992) – Argentina; Bolivia
- *[Psiloparmelia norstictica](/source/Psiloparmelia_norstictica)* Elix & T.H.Nash (1992) – Argentina; Ecuador; Peru
- *[Psiloparmelia peruviensis](/source/Psiloparmelia_peruviensis)* (Hale) Feuerer (2006)[5] – Peru; Bolivia
- *[Psiloparmelia pustulata](/source/Psiloparmelia_pustulata)* Elix & T.H.Nash (1992) – Argentina
- *[Psiloparmelia salazinica](/source/Psiloparmelia_salazinica)* Elix & T.H.Nash (1992) – Argentina; Chile
- *[Psiloparmelia sorediosa](/source/Psiloparmelia_sorediosa)* Elix & T.H.Nash (1992) – Argentina
- *[Psiloparmelia subcrustosa](/source/Psiloparmelia_subcrustosa)* Elix & T.H.Nash (1992) – Peru

## References

1. Gyelnik, V. "Additamenta ad cognitionem Parmeliarum II". *Feddes Repertorium Specierum Novarum Regni Vegetabilis*. **29**: 272–291.

1. Hale, Mason (1989). ["A new lichen genus, *Psiloparmelia* Hale (Ascomycotina: Parmeliaceae)"](http://www.cybertruffle.org.uk/cyberliber/59575/0035/001/0041.htm). *Mycotaxon*. **35** (1): 41–44.

1. Lumbsch, H. Thorsten; Schuster, Günter; Elix, John A.; Nash III, Thomas H. (1992). ["The epicortical structure of the lichen genus *Psiloparmelia* (Parmeliaceae : Ascomycotina)"](http://www.cybertruffle.org.uk/cyberliber/59575/0045/0489.htm). *Mycotaxon*. **45**: 489–494.

1. Elix, John A. & Nash, Thomas H. (1992). "A synopsis of the lichen genus *Psiloparmelia* (Ascomycotina, Parmeliaceae)". *The Bryologist*. **95** (4): 377–391. [doi:10.2307/3243562](https://doi.org/10.2307/3243562). [JSTOR 3243562](https://www.jstor.org/stable/3243562)

1. Thell, Arne; Feurerer, Tassilo; Elix, John A.; Kärnefelt, Ingvar (2006). ["A contribution to the phylogeny and taxonomy of *Xanthoparmelia* (Ascomycota, Parmeliaceae)"](https://www.jstage.jst.go.jp/article/jhbl/100/0/100_797/_pdf/-char/en). *Journal of the Hattori Botanical Laboratory*. **100**: 797–807. [doi:10.18968/jhbl.100.0_797](https://doi.org/10.18968/jhbl.100.0_797)

1. García, Renato; Magnin, Lucia; Miotti, Laura; Barrientos, Gustavo (2020). "Lichens growing on human bone remains: A case study from continental Patagonia (Deseado Massif, Santa Cruz, Argentina)". *Journal of King Saud University - Science*. **32** (3): 2219–2221. [doi:10.1016/j.jksus.2020.02.029](https://doi.org/10.1016/j.jksus.2020.02.029). [hdl:11336/136600](https://hdl.handle.net/11336/136600). [S2CID 216163263](https://api.semanticscholar.org/CorpusID:216163263)

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Adapted from the Wikipedia article [Psiloparmelia](https://en.wikipedia.org/wiki/Psiloparmelia) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Psiloparmelia?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.