# Pyxine petricola

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Species of lichen

Pyxine petricola Conservation status Apparently Secure (NatureServe)[1] Scientific classification Kingdom: Fungi Division: Ascomycota Class: Lecanoromycetes Order: Caliciales Family: Caliciaceae Genus: Pyxine Species: P. petricola Binomial name Pyxine petricola Nyl. (1876) Synonyms[2] Pyxine meissneri var. endoleuca Müll.Arg. (1879) Pyxine endoleuca (Müll.Arg.) Vain. (1898) Pyxine subvelata Stirt. (1898)

***Pyxine petricola*** is a species of [saxicolous](/source/Saxicolous_lichen) (rock-dwelling), [foliose lichen](/source/Foliose_lichen) in the family [Caliciaceae](/source/Caliciaceae).[3] The distribution of the lichen includes Australia, East Africa, North and Central America, and the Philippines.[4]

## Taxonomy

The lichen was [formally described](/source/Species_description) as a new species in 1876 by the Finish lichenologist [William Nylander](/source/William_Nylander_(botanist)). In Nylander's brief description, he mentions that *Pyxine petricola* has a slightly blue-green [thallus](/source/Thallus), spreading thinly and attaching closely to surfaces. Its reproductive structures, [apothecia](/source/Apothecia), are black, flat, and edged, with dark, oblong, two-compartment spores. The top cell layer of the apothecium is bluish-black, contrasting with the nearly colourless layer beneath. He further notes that the species typically grows on rocks.[5]

## Description

The [thallus](/source/Thallus) of *Pyxine petricola*, the lichen typically does not exceed a diameter of 40 mm (1.6 in) and features a thallus with irregular or radially arranged [lobes](/source/Glossary_of_lichen_terms#lobes). These lobes, measuring between 0.3 and 1.2 mm in width, are white or greyish white in colour and have a branching pattern that is somewhat [dichotomous](/source/Glossary_of_lichen_terms#dichotomous) (splitting into two parts) and often overlapping ([imbricate](/source/Glossary_of_lichen_terms#imbricate)), lying flat against or slightly raised from the surface. The thallus may be smooth or slightly convex, with [pseudocyphellae](/source/Pseudocyphella)—specialised pores allowing [gas exchange](/source/Gas_exchange)—visible as white lines along the margins and upper surface, sometimes forming a network ([reticulate](/source/Glossary_of_lichen_terms#reticulate)). Unlike some lichens, *Pyxine petricola* does not develop [isidia](/source/Isidia) (outgrowths for reproduction and dispersal) or [pustules](/source/Glossary_of_lichen_terms#pustules), and may or may not be covered in a fine powder ([pruina](/source/Glossary_of_lichen_terms#pruina)). The inner tissue ([medulla](/source/Medulla_(lichenology))) of the lichen is white.[4]

Reproductive structures ([apothecia](/source/Apothecia)) are commonly found within the lichen, often incorporating algae within their outer rim ([exciple](/source/Glossary_of_lichen_terms#exciple)) and featuring an internal structure (stipe) that turns red when treated with a [potassium hydroxide](/source/Potassium_hydroxide) solution (i.e., the K [spot test](/source/Spot_test_(lichen))). The [ascospores](/source/Glossary_of_lichen_terms#ascospores) measure 12–20 by 6–8 [μm](/source/%CE%9Cm).[4]

Chemically, *Pyxine petricola* is distinguished by the presence of [lichexanthone](/source/Lichexanthone) and [triterpenes](/source/Triterpene). The outer layer (cortex) of the lichen [fluoresces](/source/Fluoresce) yellow under [ultraviolet light](/source/Ultraviolet_light) but is K− and Pd−.[4]

## References

1. **[^](#cite_ref-NS_1-0)** [NatureServe](/source/NatureServe). ["*Pyxine petricola*"](https://explorer.natureserve.org/Taxon/ELEMENT_GLOBAL.2.122872/). *NatureServe Explorer*. Arlington, Virginia. Retrieved 5 November 2025.

1. **[^](#cite_ref-Species_Fungorum_synonymy_2-0)** ["GSD Species Synonymy. Current Name: *Pyxine petricola* Nyl., in Crombie, J. Bot., Lond. 14: 263 (1876)"](https://www.speciesfungorum.org/GSD/GSDspecies.asp?RecordID=355845). [Species Fungorum](/source/Species_Fungorum). Retrieved 24 February 2024.

1. **[^](#cite_ref-CoL_3-0)** ["*Pyxine petricola* Nyl"](https://www.catalogueoflife.org/data/taxon/7928R). *[Catalogue of Life](/source/Catalogue_of_Life)*. [Species 2000](/source/Species_2000): Leiden, the Netherlands. Retrieved 24 February 2024.

1. ^ [***a***](#cite_ref-Rogers_1986_4-0) [***b***](#cite_ref-Rogers_1986_4-1) [***c***](#cite_ref-Rogers_1986_4-2) [***d***](#cite_ref-Rogers_1986_4-3) Rogers, R.W. (1986). "The genus *Pyxine* (Physciaceae, lichenized ascomycetes) in Australia". *Australian Journal of Botany*. **34** (2): 131–154. [doi](/source/Doi_(identifier)):[10.1071/BT9860131](https://doi.org/10.1071%2FBT9860131).

1. **[^](#cite_ref-Crombie_1876_5-0)** Crombie, J.M. (1876). ["New Lichens from the Island of Rodriguez"](https://www.biodiversitylibrary.org/page/9103457). *Journal of Botany, British and Foreign*. **14**: 262–265.

Taxon identifiers Pyxine petricola Wikidata: Q10647724 Wikispecies: Pyxine petricola AusLichen: 30019594 BioLib: 208567 CoL: 7928R GBIF: 2609311 iNaturalist: 229700 IndexFungorum: 355845 IRMNG: 10397873 ITIS: 191017 MycoBank: 355845 NatureServe: 2.122872 NCBI: 205638 Open Tree of Life: 354561 PLANTS: PYPE SpeciesFungorum: 355845

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