Originally classified as a variety of P. omphalodes in 1803, it is characterised by its small, circular body (thallus) with narrow, highly branched, overlapping lobes, and its grey to brown upper surface contrasting with a black underside.

The lichen typically grows on siliceous (silicon-rich) rocks, and occasionally on moss, plant debris, or tree bark, showing a preference for humid environments.

It has been documented across Europe, North America, and Antarctica, with populations in mountainous regions, though its reported presence in the Southern Hemisphere requires further verification.

Kurokawa's reclassification was based on detailed studies of the lichen's morphology and chemistry, which revealed differences from closely related taxa such as P. omphalodes and P. discordans.

This clade includes several closely related species such as P. discordans, P. ernstiae, P. hygrophila, P. imbricaria, P. mayi, P. omphalodes, P. saxatilis, P. serrana, P. submontana, and P. sulymae.

In 1987, Mason Hale, in his monograph of the genus Parmelia, treated it as a synonym of P. omphalodes, suggesting the morphological differences were insufficient to warrant species status.

Modern phylogenetic analyses, using both ITS (internal transcribed spacer) and β-tubulin gene sequences, have definitively demonstrated that P. pinnatifida and P. omphalodes are genetically distinct taxa, supporting Kurokawa's original classification as separate species.

This taxonomic uncertainty, combined with its morphological similarity to P. omphalodes, has historically led to P. pinnatifida being overlooked or misidentified in field surveys, potentially affecting our understanding of its true distribution.

[6] Additionally, P. omphalodes lacks the distinctive marginal lobules characteristic of P. pinnatifida and contains lobaric acid as part of its chemical profile.

[5] Despite these morphological differences, recent phylogenetic analyses using ITS sequence data have been unable to clearly separate P. pinnatifida and P. omphalodes as distinct evolutionary lineages.

[5] While the species has been documented in Antarctica with molecular confirmation, its reported presence in southern South America and New Zealand requires additional studies to verify these distributions.

[5] In its Italian location, the species was found growing on a schist boulder at the edge of a pathway in a shady, moist and cool montane coniferous forest near a stream, demonstrating its preference for humid microhabitats.