Taxonomic Notes: This species has been the subject of much recent taxonomic work, including splitting off the segregate species Parmelia ernstiae, P. serrana, P. mayi and P. rojoi (Feuerer and Thell 2002, Molina et al. 2004, Molina et al. 2011, Crespo et al. 2020), and investigations into the diversity in the genus (Divakar et al. 2016). None of these segregate species can be diagnosed confidently using morphology only (Corsie et al. 2019). Nevertheless, we suspect P. saxatilis s. str. remains an abundant macrolichen on rocks and trees throughout the northern temperate and boreal zone.
Parmelia saxatilis is common and abundant in many forests, heaths, and uplands outside the tropics and does not qualify for any threat categories. It is, therefore, listed as Least Concern.
Assessor/s: Yahr, R., Allen, J., Lymbery, C., Batallas-Molina, R., Bungartz, F., Dal Forno, M., Howe, N., Lendemer, J., McMullin, T., Mertens, A., Paquette, H., Petix, M., Reese Næsborg, R., Roberts, F., Sharrett, S. & Villella, J.; Reviewer/s: Divakar, P.; Contribu(s): Anderson, F., Calabria, L., Glew, K., Hollinger, J., Hodges, M., Kaminsky, L., Noell, N., Parrinello, C., Ramos, D., Restrepo, A., Root, H., Rosentreter, R., Scott, T., Stone, D. & Vargas, R.; Partner(s) and Institution(s): Royal Botanic Garden Edinburgh.
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Find out more about the IUCN Red List Categories and Criteriahere.
Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2002. Lichen Flora of the Greater Sonoran Desert Region. Vol 1.
Thallus: adnate, foliose, 4-20 cm in diam., lobate lobes: sublinear, contiguous, elongate, plane to subconvex, separate, 2-4 mm wide, apices truncate upper surface: gray (to brown in exposed habitats), smooth to foveolate, shiny, sometimes white pruinose, becoming cracked along prominent, effigurate pseudocyphellae isidia: cylindrical, simple to coralloid, abundant, laminal, dense; soredia and pustulae absent medulla: white with continuous algal layer lower surface: black, rhizinate, rhizines: moderately dense, black, simple to furcate Apothecia: rare, laminal, 2-8 mm wide; margin: usually isidiate; disc: red-brown to dark brown asci: clavate, 8-spored ascospores: ellipsoid, 16-18 x 9-11 µm Pycnidia: not seen Spot tests: upper cortex K+ yellow, C-, KC-, P+ yellow; medulla K+ yellow turning deep red, C-, KC-, P+ orange Secondary metabolites: upper cortex with atranorin and chloroatranorin; medulla with salazinic acid (major) and consalazinic acids (minor). Substrate and ecology: on rocks in open habitats, rarely on trees World distribution: pantemperate and southern boreal Sonoran distribution: relatively rare on scree rocks in upper montane habitats, Arizona.