He further noted that the type specimen, collected by Johan Petter Norrlin,[4] was found growing on bark in Etelä-Häme [fi] (Hollola, Finland).

The taxon was transferred to Melanohalea, along with 18 other brown parmelioid species that are primarily distributed on bark and wood in the Northern Hemisphere.

[11] The genus Melanohalea, including M. exasperatula, underwent significant diversification primarily during the Miocene and Pliocene epochs, much earlier than the Pleistocene glacial cycles.

Melanohalea exasperatula's current distribution and population structure are the result of both ancient diversification events and more recent ecological adaptations.

Moderate levels of both haplotype and nucleotide diversity in M. exasperatula suggest that the species has sufficient genetic variation to adapt to various environments, supporting its wide distribution.

[13] A genealogical concordance method used in the study found strong evidence for previously unrecognized species-level lineages within traditional morphology-based species, including M. exasperatula.

This implies that there may be cryptic diversity within what is currently recognized as M. exasperatula, necessitating further morphological and genetic studies to fully resolve the species boundaries.

[14] The shiny upper surface of the thallus varies in colour from pale olive-green to dark olive-brown or red-brown and becomes somewhat transparent when wet.

[14] Melanohalea elegantula is somewhat similar in appearance to M. exasperatula, but the former species can be distinguished by its isidia, which are cylindrical and compact, and its thicker and usually darker thallus.

It can also be found on open hillsides, occasionally growing on rocks (saxicolous), walls, and wooden fence rails under trees.

[14] In Greenland, it occurs on the bark of dwarf shrubs and the wood of Picea, and on both siliceous and basaltic rocks, usually in nutrient-enriched habitats.

[12] Melanohalea exasperatula shows a significant ability for dispersal and is commonly found in nutrient-rich habitats, including urban areas and places with anthropogenic disturbances.

This species, along with M. elegantula, shows potential for broad geographic spread, which is notable as it contrasts with other Melanohalea lineages that have more restricted distributions.

This preference suggests that the absence of chemical defenses in M. exasperatula influences its distribution and abundance, leading to heavier grazing in natural habitats.

Demonstrating the impact of herbivory on lichen community dynamics and ecological niches, M. exasperatula is as a consequence often found in more sun-exposed areas with lower gastropod activity.