Buellia arida

Buellia arida grows up to 40 mm (1.6 in) wide, either hidden within rocks or visible on rock surfaces. Its visible form appears as small, broken, skin-like patches around the lichen's fruiting bodies or in rock crevices. The thallus is off-white and dull, with algae cells measuring 8–19 μm wide. The lichen's fruiting bodies, known as apothecia, are numerous, black, and can become convex with age, surrounded by a thin outer layer. The spore-bearing tissue is colourless, while the supporting tissue beneath ranges from brown to deep red-brown. Buellia arida has sparsely branched thread-like structures (paraphyses) in its fertile tissue, with brown-tipped branches, and produces two-part spores that are ellipsoid and change from pale to dark brown, with a finely decorated outer surface. Rarely, the lichen has pycnidia, which have black openings and produce rod-shaped spores. The spores themselves are of the Buellia type, divided into two parts by a single septum, change from pale brown to dark brown as they mature, and are ellipsoid in shape, measuring 11–17 by 5–7 μm.^[1]

Buellia arida is similar to Buellia abstracta, but is distinguished by larger ascospores and longer conidia.^[1]

The species is found in far-western New South Wales and southern parts of the Northern Territory. Commonly associated lichens include Buellia dispersa, B. spuria var. amblyogona, Filsoniana australiensis, Sarcogyne iridana, and Xanthoparmelia cravenii.^[1]