ASCOMYCOTA | LECANOROMYCETES > LECANORALES > Parmeliaceae

Genus Punctelia, meaning 'dotted' from the shape and positioning of the pseudocyphellae

Common name:            Forest Speckled Shield Lichen

Synonym:                    Parmelia subrudecta

Habitat:                          Open woodland, wayside trees

Substrata:                     Bark, sometimes wood

Growth forms:              Corticolous, lignicolous (saxicolous)

Thallus:                  Foliose

Apothecia:                    Lecanorine, absent or rare

BLS identity rating:        Graded 2/5 (visual identification possible with care)

Foliose thallus typically rosette-forming, growing to around 3-7cm dia; tightly adpressed to the substratum centrally, more loosely at the tips where the lobes are usually slightly raised and wavy; individual lobes 5-10mm broad with somewhat irregular rounded margins, generally smooth and, particularly when young, with dark shiny extreme edges; radiating, contiguous or overlapping, becoming somewhat contorted centrally.

Upper surface pale greenish-grey when fresh, distinctly greener when moist; when young, the lobes are scattered with minute round or sightly elongated white dot-like pseudocyphellae, which are usually limited to the base of the lobes, not at the edge, but becoming sparse or even absent in mature thalli; the surface, and sometimes the lobe margins, have medium grey, quite course, punctiform soralia producing finely granular soredia; the underside of the lobes are creamy white to pale brown, only slightly darker towards the centre; rhizines dense, sometimes clumped together, but not extending to the margins

Apothecia very rare but, where present, hardly stalked, discs to 5mm dia., red-brown, deeply concave with an unevenly crenate margin; pycnidia occasionally present, visible on the thallus surface as tiny black dots.

Punctelia subrudecta is a common and relatively widespread species particularly across central and southern areas, but becoming somewhat rarer further north. It can primarily be found on the bark of well-lit broadleaved trees, but also, more rarely, on weathered wood, or amongst mosses on siliceous rocks, walls, roofing tiles etc.

The species could visually be mistaken for Punctelia borreri as previously described, but can usually be distinguished by the much paler underside. It is also less shiny, less flattened and has more pseudocyphellae towards the ends of the lobes. Also, with Punctelia jeckeri, although that species is more greenish to brownish-grey with an overall duller appearance. And, possibly with smaller specimens of Cetrelia olivetorum, which has a thallus that often grows to 20cm, with much larger, broader lobes.