{{Short description|Species of lichen}} {{Use dmy dates|date=March 2021}} {{Speciesbox | image = | image_caption = | taxon = Punctelia negata | authority = (Nyl.) Krog (1982) | synonyms_ref = <ref name="Species Fungorum synonymy"/> | synonyms = *''Parmelia negata'' {{small|Nyl. (1872)}} }}

'''''Punctelia negata''''' is a little-known species of foliose lichen in the family Parmeliaceae. It is found in South America.

==Taxonomy== The lichen was described as a new species by Finnish lichenologist William Nylander in 1872. Giving a brief diagnosis in a footnote, he distinguished it from the similar species ''P.&nbsp;rudecta'' and ''P.&nbsp;borreri'' by its longer ascospores and conidia, and its more wrinkled amphithecia (the inner layer of the perithecium next to the hymenium).<ref name="Nylander 1872"/> The original specimens were collected by Alexander Lindig in "Nova Granata" (i.e. [= Republic of New Granada], specifically Bogotá, Colombia), at an altitude of {{convert|2600|m|ft|abbr=on}}.<ref name="Canêz et al. 2016"/> In 1982, Norwegian botanist Hildur Krog transferred the taxon to the newly circumscribed ''Punctelia'', a segregate genus from ''Parmelia'' created to contain species with rounded pseudocyphellae.<ref name="Krog 1982"/>

The lichen is not well understood and has rarely been gathered since it was described. Specimens reportedly collected from Rio Grande do Sul and from Paraná in 1999 and 2001 were examined later and determined to have been misidentified, representing instead the species ''Punctelia borrerina''. Consequently, the only verified material of ''Punctelia negata'' is the holotype and isotypes collected from the type locality in Colombia.<ref name="Canêz et al. 2016"/>

==Description== Major characteristics of ''Punctelia negata'' include the presence of small lobes (lobules) on the upper thallus surface, a pale brown lower thallus surface, long threadlike (filiform) conidia, ascospores measuring 19–23&nbsp;μm long, and a medulla that reacts C− in a lichen spot test.<ref name="Canêz et al. 2016"/>

A high-pressure liquid chromatography analysis of the type specimen revealed several secondary chemicals, including protoconstipatic acid and constipatic acid as major products, and dehydroconstipatic acid, protodehydroconstipatic acid, atranorin, and chloroatranorin as minor products.<ref name="Canêz et al. 2016"/>

==References== {{Reflist|refs=

<ref name="Canêz et al. 2016">{{cite journal |last1= Canêz |first1=Luciana S. |last2=Spielmann |first2=Adriano A. |last3=Marcelli |first3=Marcelo P. |last4=Elix |first4=John A. |year=2016 |title=An accurate circumscription of the poorly known ''Punctelia negata'' (Nyl.) Krog |journal=Iheringia, Série Botânica |volume=71 |issue=3 |pages=257–260}}</ref>

<ref name="Krog 1982">{{cite journal |last1=Krog |first1=Hildur |year=1982 |title=''Punctelia'', a new lichen genus in the Parmeliaceae |journal=Nordic Journal of Botany |volume=2 |issue=3 |pages=287–292 |doi=10.1111/j.1756-1051.1982.tb01191.x}}</ref>

<ref name="Nylander 1872">{{cite journal |last1=Nylander |first1=William |year=1872 |title=Observata lichenologica in Pyrenaeis orientalibus. I. Forca-Réale; II. La Preste-Costabonne |journal=Flora Regensburg |volume=55 |pages=545–554 |url=https://www.biodiversitylibrary.org/page/61305 |language=la}}</ref>

<ref name="Species Fungorum synonymy">{{cite web |title=Synonymy: ''Punctelia negata'' (Nyl.) Krog, Nordic Jl Bot. 2(3): 291 (1982) |url=http://www.speciesfungorum.org/Names/SynSpecies.asp?RecordID=110974 |publisher=Species Fungorum |access-date=22 March 2021}}</ref>

}}

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negata Category:Lichen species Category:Lichens of Colombia Category:Lichens described in 1872 Category:Taxa named by William Nylander (botanist)