# Letharia

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***Letharia*** is a [genus](/source/Genus) of [fruticose](/source/Fruticose_lichen) [lichens](/source/Lichen) belonging to the family [Parmeliaceae](/source/Parmeliaceae).[1] [Molecular phylogenetics](/source/Molecular_phylogenetics) studies have revealed that what were once considered just two species actually represent at least several distinct evolutionary [lineages](/source/Lineage_(evolution)), with western North America serving as the centre of diversity for the group. These lichens typically grow on sun-exposed wood and bark of [coniferous](/source/Coniferous) trees, growing in dry habitats where they receive moisture from [dew](/source/Dew) or [fog](/source/Fog).

## Taxonomy

Historically only two species were recognised in *Letharia*: *[L. vulpina](/source/Letharia_vulpina)* and *[L. columbiana](/source/Letharia_columbiana)*. The traditional distinction between the two species was treated as a classic lichen , with [sorediate](/source/Soredia) thalli assigned to *L. vulpina* and fertile thalli with abundant [ascomata](/source/Ascoma) assigned to *L. columbiana*. Altermann and colleagues noted, however, that this separation was imperfect, because some *L. columbiana* specimens also produce [isidia](/source/Isidia), while typically sorediate *L. vulpina* can occasionally bear apothecia.[2] A 2016 multi-locus [molecular](/source/Molecular_phylogenetics) study that sequenced three fungal and two algal markers from 302 thalli retrieved at least six well-supported, reproductively independent [lineages](/source/Lineage_(evolution))—two within the traditional *L. vulpina* concept and four within *L. columbiana* *sensu lato*. One of the former was formally described as *[Letharia lupina](/source/Letharia_lupina)*. To stabilise usage of the name *L. columbiana*, Altermann and colleages designated a freshly sequenced specimen from the [Walla Walla River](/source/Walla_Walla_River) valley ([Oregon](/source/Oregon)) as an [epitype](/source/Epitype), because the 1833 [holotype](/source/Holotype) is a degraded, mixed gathering dominated by *L. vulpina* and riddled with contaminants. Three further lineages—*[L. gracilis](/source/Letharia_gracilis)*, *[L. barbata](/source/Letharia_barbata)* and *[L. rugosa](/source/Letharia_rugosa)*—were judged likely to merit species rank once additional diagnostic data become available. Each fungal species partners exclusively with a distinct clade inside *[Trebouxia jamesii](/source/Trebouxia_jamesii)* *sensu lato*, showing that *Letharia* represents several discrete symbioses rather than a single variable [species complex](/source/Species_complex).[3] An earlier multilocus study based on 432 specimens broadly recovered the same six candidate lineages proposed in earlier molecular work, but found that the strongest and most consistent separation was between the sorediate groups later treated as *L. lupina* and *L. vulpina*, while relationships among the apotheciate lineages remained less certain.[2]

The same work shows that western North America is the centre of diversity for the group: *L. lupina* alone accounted for 88% of nearly 300 North American collections and ranges from valley bottoms to the alpine [tree line](/source/Tree_line), extending east of the [Continental Divide](/source/Continental_Divide) into [Alberta](/source/Alberta) and the northern [Rocky Mountains](/source/Rocky_Mountains). By contrast, *L. vulpina* is largely confined to lower, drier conifer forests and is much rarer on the continent, though it remains the prevalent *Letharia* in Europe. Traditional [morphological](/source/Morphology_(biology)) characters such as branch density, branch colour and [isidial](/source/Isidia) abundance were found to vary widely within species, rendering them unreliable for routine identification; instead, fixed [nucleotide](/source/Nucleotide) differences in the DNA sequence, or [PCR](/source/Polymerase_chain_reaction)-[RFLP](/source/Restriction_fragment_length_polymorphism) assays, allow rapid discrimination between *L. vulpina* and *L. lupina*.[3]

## Habitat and distribution

*Letharia lupina* occurs across a broad spectrum of habitats and elevations, extending from valley [woodlands](/source/Woodland) at about 190 m to alpine [tree line](/source/Tree_line) near 3370 m. It is most frequently encountered on sun-bleached, decorticated [conifer](/source/Conifer) timber—old fence posts, fallen [trunks](/source/Trunk_(botany)) and branches of *[Pinus](/source/Pinus)* in particular—and also spreads to the bark of *[Abies](/source/Abies)*, *[Picea](/source/Picea)*, *[Calocedrus](/source/Calocedrus)* and *[Pseudotsuga](/source/Pseudotsuga)*. Less commonly it [colonises](/source/Colonisation_(biology)) weather-worn [hardwoods](/source/Hardwood) such as *[Arbutus](/source/Arbutus)*, *[Populus](/source/Populus)* and *[Salix](/source/Salix)*, or even [granitic](/source/Granitic) outcrops.[3]

By contrast, *L. vulpina* is confined mainly to drier low-elevation conifer forests and [chaparral](/source/Chaparral), seldom occurring above roughly 800 m in the north or 1600 m in the south of its range. It shares a preference for lignified (woody) [substrates](/source/Substrate_(biology))—fence rails and the wood or bark of *[Pseudotsuga menziesii](/source/Pseudotsuga_menziesii)*, *[Pinus ponderosa](/source/Pinus_ponderosa)* and related conifers are typical—but is otherwise less particular in its choice of [hosts](/source/Host_(biology)). Field observations suggest that both species prosper in sunny, summer-dry habitats where nightly dew or fog provides brief moisture pulses needed for [photosynthesis](/source/Photosynthesis).[3]

Outside western North America, the genus also occurs in continental Europe, northern Africa, Cyprus and the Caucasus, although it is much less common in the Old World and has been reported as declining in northern Europe.[2]

## Species

- *[Letharia columbiana](/source/Letharia_columbiana)* [4]
- *[Letharia gracilis](/source/Letharia_gracilis)*
- *[Letharia lupina](/source/Letharia_lupina)* [3]
- *[Letharia pirionii](/source/Letharia_pirionii)* [5]
- *[Letharia subdivaricata](/source/Letharia_subdivaricata)*
- *[Letharia vulpina](/source/Letharia_vulpina)*

## References

1. Wijayawardene, Nalin; Hyde, Kevin; Al-Ani, Laith Khalil Tawfeeq; Somayeh, Dolatabadi; Stadler, Marc; Haelewaters, Danny et al. (2020). "Outline of Fungi and fungus-like taxa". *Mycosphere*. **11**: 1060–1456. [doi:10.5943/mycosphere/11/1/8](https://doi.org/10.5943/mycosphere/11/1/8). [hdl:10481/61998](https://hdl.handle.net/10481/61998)

1. Altermann, Susanne; Leavitt, Steven D.; Goward, Trevor; Nelsen, Matthew P.; Lumbsch, H. Thorsten (2014). "How do you solve a problem like *Letharia*? A new look at cryptic species in lichen-forming fungi Using Bayesian clustering and SNPs from multilocus sequence data". *PLoS ONE*. **9** (5). [doi:10.1371/journal.pone.0097556](https://doi.org/10.1371/journal.pone.0097556). [PMC 4022584](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4022584). [PMID 24831224](https://pubmed.ncbi.nlm.nih.gov/24831224)

1. Altermann, Susanne; Leavitt, Steven D.; Goward, Trevor (2016). "Tidying up the genus *Letharia*: introducing *L. lupina* sp. nov. and a new circumscription for *L. columbiana*". *The Lichenologist*. **48** (5): 423–439. [doi:10.1017/S0024282916000396](https://doi.org/10.1017/S0024282916000396)

1. Thomson, John W. (1969). "*Letharia californica* is *Letharia columbiana* (Lichenes)". *Taxon*. **18** (5): 535–537. [doi:10.2307/1218380](https://doi.org/10.2307/1218380). [JSTOR 1218380](https://www.jstor.org/stable/1218380)

1. Bouly de Lesdain, M. (1935). "Notes lichénologiques. XXVIII" (in French). *Bulletin de la Société Botanique de France*. **82**: 314–317. [doi:10.1080/00378941.1935.10832983](https://doi.org/10.1080/00378941.1935.10832983)

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