Xanthoparmelia nodulosa

Xanthoparmelia nodulosa is a little-known species of saxicolous foliose lichen in the family Parmeliaceae. It is only known to occur in Western Australia.

Taxonomy

Xanthoparmelia nodulosa was first described by the lichenologist John Elix in 2006. The specific epithet, nodulosa, comes from the Latin nodulus, meaning "nodule", referring to the, nodule-like isidia characteristic of this species.

Description

Xanthoparmelia nodulosa features a foliose, loosely attached thallus that forms rosettes ranging from 1 to 4 cm wide. The are separate to loosely, linear-elongate, and branched, measuring 0.3 to 1.0 mm wide. The upper thallus surface is yellow to pale yellow-green, transitioning from flat to weakly convex, and becomes and with age, featuring distinctive white towards the lobe tips. This species lacks soredia but produces isidia in small, scattered groups that are spherical at first and then cylindrical or. The medulla is white, while the lower surface is smooth and yellow, turning in parts. Rhizines are sparse,, or often, and black, extending beyond the lobe margin. Chemical tests reveal the presence of usnic acid, fumarprotocetraric acid, and several other trace compounds.

Habitat and distribution

As of its original publication date, Xanthoparmelia nodulosa was known only from its type locality in Western Australia, specifically Boorabbin Rock in the Boorabbin National Park. It grows on soil over granite boulders within Allocasuarina–''Acacia'' woodland.
The cortex reacts K−, while the medulla reacts K+, C−, and P+. Chemical constituents include usnic acid, fumarprotocetraric acid, succinprotocetraric acid, and traces of other acids.