| Punctelia rudecta | |
|---|---|
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| In Cataloochee (Great Smoky Mountains), North Carolina; growing on the upper trunk of a red maple tree | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Fungi |
| Division: | Ascomycota |
| Class: | Lecanoromycetes |
| Order: | Lecanorales |
| Family: | Parmeliaceae |
| Genus: | Punctelia |
| Species: | P. rudecta
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| Binomial name | |
| Punctelia rudecta | |
| Synonyms[1] | |
Punctelia rudecta, commonly known as the rough speckled shield or the speckleback lichen, is a North American species of foliose lichen in the family Parmeliaceae. This species can be readily identified by the light color of the thallus underside, the relatively large lobes at the edges of the thallus, and the tiny white pores present on the top of the thallus that are characteristic of the genus Punctelia. The lichen is quite abundant and widespread in the eastern and southeastern United States, although it also occurs in Canada and northern Mexico, but is less common in these regions. The lichen usually grows on bark, and less commonly on shaded rocks. There are several lookalike Punctelia species; these can often be distinguished from P. rudecta by differences in distribution or in the nature of the reproductive structures present on the thallus.
Although Punctelia rudecta was previously thought to have a much more expansive global distribution, phylogenetic analysis revealed a species complex that has subsequently been split into four distinct cryptic lineages with more restricted distributional ranges. Punctelia rudecta is moderately sensitive to air pollution and has been assessed as a suitable candidate for biomonitoring air quality.