{{Short description|Species of lichen}} {{Use dmy dates|date=June 2025}} {{Species box | image = Pyxine subcinerea Stirton 420916.jpg | status = G4 | status_system = TNC | status_ref = <ref name=NS>{{cite NatureServe |id=2.124919 |title=''Pyxine subcinerea'' |access-date=5 November 2025}}</ref> | taxon = Pyxine subcinerea | authority = [[Stirt.]] (1898) | synonyms_ref = <ref name="Species Fungorum synonymy"/> | synonyms = *''Pyxine cocoes'' var. ''caesiopruinosa'' {{au|[[Tuck.]] (1869)}} *''Pyxine meissneri'' var. ''sorediosa'' {{au|[[Müll.Arg.]] (1879)}} *''Physcia melanenta'' {{au|[[C.Knight]] (1882)}} *''Pyxine sorediata'' f. ''caesiopruinosa'' {{au|(Tuck.) [[Auguste-Marie Hue|Hue]] (1900)}} *''Pyxine chrysanthoides'' {{au|[[Vain.]] (1915)}} *''Pyxine caesiopruinosa'' {{au|(Tuck.) [[Imshaug]] (1957)}} }}

'''''Pyxine subcinerea''''' is a species of [[foliose lichen]] in the family [[Caliciaceae]]. It has a [[pantropical]] distribution, and typically [[corticolous lichen|grows on bark]], but less commonly [[saxicolous lichen|on rocks]]. The lichen is characterised by its yellow [[medulla (lichenology)|medulla]], [[soralia]] on the margins on the lobes that make up the [[thallus]], and the presence of the chemical [[lichexanthone]] in the [[cortex (botany)|cortex]].

==Taxonomy==

The lichen was first [[species description|formally described]] by the Scottish scientist [[James Stirton]] from specimens collected in [[Queensland, Australia]]. He noted that its thallus was similar to that of ''[[Pyxine sorediata]]'', but Stirton distinguished it from that species by the "internal organization of both the thallus and the apothecia", as well as the negative K reaction of the thallus, compared to the yellow reaction of ''P.&nbsp; sorediata''.<ref name="Stirton 1897"/>

[[Synonym (biology)|Synonyms]] of ''Pyxine subcinerea'' include:<ref name="Species Fungorum synonymy"/> ''Physcia melanenta'', described by [[Charles Knight (doctor)|Charles Knight]] in 1882;<ref name="Knight 1882"/> ''Pyxine chrysanthoides'', described by [[Edvard August Vainio]] in 1915 from material collected in the [[Antilles]];<ref name="Vainio 1915"/> ''Pyxine meissneri'' var. ''sorediosa'', described by [[Johannes Müller Argoviensis]] in 1879;<ref name="Müller 1879"/> and ''Pyxine cocoes'' var. ''caesiopruinosa'', described by [[Edward Tuckerman]] in 1869<ref name="Nylander 1869"/> (and later promoted to distinct species status as ''Pyxine caesiopruinosa'' by [[Henry Andrew Imshaug]] in 1957).<ref name="Imshaug 1957"/>

==Description== [[File:Pyxine subcinerea - Flickr - pellaea.jpg|thumb|upright=0.8|right|Closeup of lobes; the scale bar is 0.5&nbsp;mm.]] The [[thallus]] of ''Pyxine subcinerea'' is {{convert|3|–|8|cm|in|abbr=on}} wide, with an upper surface ranging in colour from yellowish grey to grey to brownish grey or olive-grey. The lobes that comprise the thallus are {{convert|0.3|–|1.5|mm|in|abbr=on|2}} wide, somewhat tightly apressed to the [[substrate (biology)|substrate]] and are more or less flat but often somewhat concave near the tips. The lobe surface are [[pruinose]], with the pruina resembling dense points near the lobe tips.<ref name="Elix 2009"/> These pruina contain [[weddellite]], a mineral form of [[calcium oxalate]].<ref name="Modenesi et al. 2007"/> There are distinct [[pseudocyphella]]e at the margins of the lobes. The soralia are near the lobe margins. The [[medulla (lichenology)|medulla]] is quite thin and yellow above. The lower surface is black in the centre, but becomes paler towards the margin. Rhizines are more or less dense, and divided into branches.<ref name="Elix 2009"/> The upper [[cortex (botany)|cortex]] is paraplectenchymatous (a cell arrangement where the [[hypha]]e are oriented in all directions), while the lower cortex is prosoplectenchymatous (a cell arrangement where the hyphae are all oriented in one direction).<ref name="Moberg 1983"/> [[Apothecia]] (reproductive structures) are common in tropical and subtropical specimens; they measure {{convert|0.3|–|1.5|mm|in|abbr=on|2}} wide and have an indistinct internal [[stipe (mycology)|stipe]].<ref name="Elix 2009"/> In contrast, apothecia are not typically associated with European material.<ref name="Moberg 1983"/> [[Ascospore]]s measure 13–22 by 6–9&nbsp;[[micrometre|μm]]. The [[conidia]] are [[bacilliform]], and measure 3–4&nbsp;μm by about 1&nbsp;μm.<ref name="Elix 2009"/>

The [[secondary metabolite|secondary chemical]] in ''Pyxine subcinerea'' is [[lichexanthone]].<ref name="Elix 2009"/> The presence of this compound results in a golden-yellow colour when illuminated with [[UV light]].<ref name="Amtoft 2002"/> All [[lichen spot test]]s are negative.<ref name="Moberg 1983"/>

==Habitat and distribution==

''Pyxine subcinerea'' has a mostly [[pantropical]] distribution. Although it is generally found [[corticolous lichen|growing on bark]], it has also been found [[saxicolous lichen|growing on rock]],<ref name="Moberg 1983"/> and, in one instance, on [[mortar (masonry)|mortar]].<ref name="Amtoft 2002"/> In Europe, it has been reported from the [[Azores]] and Italy.<ref name="Moberg 1983"/> It has been reported from Africa (Ethiopia, Uganda, Kenya, Tanzania, the Seychelles, Rwanda and Angola),<ref name="Bock et al. 2007"/> throughout Asia (including China),<ref name="Yang et al. 2019"/> Australia,<ref name="Elix 2009"/> New Zealand,<ref name="Hayward & Hayward 1990"/> In the eastern United States, its geographical range covers [[subtropical]] to more [[temperate]] regions, including the states of [[New York (state)|New York]], [[Illinois]], and [[Ohio]] to [[Florida]], [[Louisiana]], and [[Texas]]. ''Pyxine subcinerea'' has been recorded growing on [[hornbeam]], [[hickory]], [[hibiscus]], [[juniper]], [[sweetgum]], [[magnolia]], [[oak]], [[robinia|locust]], [[elm]], and the genus ''[[Prunus]]''. It tends to prefer low elevations, and occurs hardwood-[[pine]] forests as well as more open areas including farms, glades, and gardens.<ref name="Amtoft 2002"/>

''Pyxine subcinerea'' is relatively resistant to [[air pollution]], and has been investigated for use as a candidate for [[biomonitor]]ing. It [[bioaccumulation|bioaccumulates]] toxic [[heavy metals]] that it acquires from the air and retains the pollutants in the thallus, which can then be sampled and [[assay]]ed to determine their concentration.<ref name="Shukla & Upreti 2007"/><ref name="Shukla & Upreti 2011"/>

==References== {{Reflist|colwidth=30em|refs=

<ref name="Amtoft 2002">{{cite journal |last1=Amtoft |first1=Anja |title=''Pyxine subcinerea'' in the Eastern United States |journal=The Bryologist |volume=105 |issue=2 |year=2002 |pages=270–272 |doi=10.1639/0007-2745(2002)105[0270:PSITEU]2.0.CO;2 |url=http://curis.ku.dk/ws/files/33289617/Amtoft_2002_subcinerea.pdf}}</ref>

<ref name="Bock et al. 2007">{{cite journal |last1=Bock |first1=Christina |last2=Hauck |first2=Markus |last3=Fischer |first3=Eberhard |year=2007 |title=The lichen flora of Rwanda: an annotated checklist |journal=Willdenowia |volume=37 |issue=2 |pages=563–575 |doi=10.3372/wi.37.37216 |doi-access=free}}</ref>

<ref name="Elix 2009">{{cite book |author-link=John Alan Elix |last1=Elix |first1=John Alan |year=2009 |title=Flora of Australia |chapter=Physciaceae |volume=57 |page=532 |location=Canberra & Melbourne |publisher=CSIRO Publishing |isbn=978-0-643-09664-6}}</ref>

<ref name="Hayward & Hayward 1990">{{cite journal |last1=Hayward |first1=Bruce W. |last2=Hayward |first2=Glenys C. |title=Lichens of Whale (Motuhora) and Rurima Islands, Bay of Plenty, New Zealand |journal=Tane |year=1990 |volume=32 |pages=61–71 |url=http://www.thebookshelf.auckland.ac.nz/docs/Tane/Tane-32/7%20Lichens%20of%20Whale%20Island.pdf}}</ref>

<ref name="Imshaug 1957">{{cite journal |last1=Imshaug |first1=H.A. |year=1957 |title=The lichen genus ''Pyxine'' in North and Middle America |journal=Transactions of the American Microscopical Society |volume=76 |issue=3 |pages=246–269 |doi=10.2307/3223889 |jstor=3223889}}</ref>

<ref name="Knight 1882">{{cite journal |last1=Knight |first1=C. |year=1882 |title=Contributions to the Lichenographia of New South Wales |journal=Transactions of the Linnean Society of London |series=2nd Series |volume=2 |pages=37–51 |url=https://www.biodiversitylibrary.org/page/784460}}</ref>

<ref name="Moberg 1983">{{cite journal |last1=Moberg |first1=R. |title=Studies on Physciaceae (Lichens) II. The genus ''Pyxine'' in Europe |journal=The Lichenologist |volume=15 |issue=2 |year=1983 |pages=161–167 |doi=10.1017/S0024282983000250}}</ref>

<ref name="Modenesi et al. 2007">{{cite journal |last1=Modenesi |first1=P. |last2=Bombardi |first2=V. |last3=Giordani |first3=P. |last4=Brunialti |first4=G. |last5=Corallo |first5=A. |title=Dissolution of weddellite, calcium oxalate dihydrate, in ''Pyxine subcinerea'' |journal=The Lichenologist |volume=33 |issue=3 |year=2007 |pages=261–266 |doi=10.1006/lich.2001.0321}}</ref>

<ref name="Müller 1879">{{cite journal |last1=Müller |first1=J. |year=1879 |title=Lichenologische Beiträge IX |journal=Flora (Regensburg) |volume=62 |issue=19 |pages=289–298 |language=la}}</ref>

<ref name="Nylander 1869">{{cite book |last=Nylander |first=W. |year=1869 |title=Synopsis Methodica Lichenum Omnium hucusque Cognitorum, Praemissa Introductione Lingua Gallica |volume=2 |page=2 |language=la}}</ref>

<ref name="Shukla & Upreti 2007">{{cite journal |last1=Shukla |first1=Vertika |last2=Upreti |first2=Dalip K. |title=Effect of metallic pollutants on the physiology of lichen, ''Pyxine subcinerea'' Stirton in Garhwal Himalayas |journal=Environmental Monitoring and Assessment |volume=141 |issue=1–3 |year=2007 |pages=237–243 |doi=10.1007/s10661-007-9891-z |pmid=17879139}}</ref>

<ref name="Shukla & Upreti 2011">{{cite journal |last1=Shukla |first1=Vertika |last2=Upreti |first2=Dalip K. |title=Changing lichen diversity in and around urban settlements of Garhwal Himalayas due to increasing anthropogenic activities |journal=Environmental Monitoring and Assessment |volume=174 |issue=1–4 |year=2010 |pages=439–444 |doi=10.1007/s10661-010-1468-6 |pmid=20440642}}</ref>

<ref name="Species Fungorum synonymy">{{cite web |title=Synonymy: ''Pyxine subcinerea'' Stirt. |url=http://www.speciesfungorum.org/Names/SynSpecies.asp?RecordID=403622 |publisher=[[Species Fungorum]] |access-date=21 February 2021}}</ref>

<ref name="Stirton 1897">{{cite journal |last1=Stirton |first1=J. |year=1897 |title=A new classification of the genus ''Pyxine'' |journal=Transactions of the New Zealand Institute |volume=30 |pages=393–398 |url=https://www.biodiversitylibrary.org/page/25449751}}</ref>

<ref name="Vainio 1915">{{cite journal |last1=Vainio |first1=E.A. |year=1915 |title=Additamenta ad lichenographiam Antillarum illustrandum |journal=Annales Academiae Scientiarum Fennicae |volume=6 |issue=7 |page=71 |language=la}}</ref>

<ref name="Yang et al. 2019">{{cite journal |last1=Yang |first1=Mei-Xia |last2=Wang |first2=Xin-Yu |last3=Liu |first3=Dong |last4=Zhang |first4=Yan-Yun |last5=Li |first5=Li-Juan |last6=Yin |first6=An-Cheng |last7=Scheidegger |first7=Christoph |last8=Wang |first8=Li-Song |title=New species and records of ''Pyxine'' (Caliciaceae) in China |journal=MycoKeys |year=2019 |issue=45 |pages=93–109 |doi=10.3897/mycokeys.45.29374|pmid=30733639 |pmc=6363720 |doi-access=free}}</ref>

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[[Category:Pyxine|subcinerea]] [[Category:Lichen species]] [[Category:Lichens of Africa]] [[Category:Lichens of Asia]] [[Category:Lichens of Australia]] [[Category:Lichens of Europe]] [[Category:Lichens of New Zealand]] [[Category:Lichens of the United States]] [[Category:Lichens described in 1898]] [[Category:Taxa named by James Stirton]] [[Category:Lichens of Seychelles]] [[Category:Fungi without expected TNC conservation status]] [[Category:Lichens of Macaronesia]]