Cameronia pertusarioides

The lichen forms a thick, pale lemon-yellow crust (the thallus) that can spread into extensive, irregular patches (sometimes tens of centimetres across). The surface is usually smooth to slightly glossy and tends to become strongly cracked into an irregular mosaic. Thallus margins that are actively growing may be a little thickened and somewhat folded. The thallus is typically about 0.7–1 mm thick and lacks a distinct outer cortex (it is "ecorticate"). Internally, it has a white, chalky medulla packed with minute crystals; these crystals are conspicuous under polarised light and dissolve slowly in potassium hydroxide. In the field the thallus often sheds water rather than wetting easily, an effect Kantvilas linked to the dense, crystal-rich tissues.^[2]

The photobiont is a coccoid green alga. The fruiting bodies are perithecioid (flask-shaped) and are deeply embedded in the thallus, often betrayed only by tiny greyish depressions or pinhole-like perforations at the surface. Inside, the asci occur in small clusters and are four-spored; they are broadly obovate and have a strongly iodine-reactive ("hemiamyloid") outer wall but a well-developed tholus that is essentially non-amyloid. The ascospores are hyaline and muriform (divided by many cross-walls into a brick-like pattern), broadly ellipsoid to ovate, and large (about 48–72 micrometres long). Asexual reproduction occurs via immersed pycnidia that produce bacilliform to bone-shaped conidia. Chemically, the species produces the 9-O-methylpannaric acid chemosyndrome; the thallus is UV+ (bright lemon-yellow).^[2]

Cameronia pertusarioides is known only from Tasmania, where it occurs at alpine elevations on Jurassic-era dolerite. It is especially frequent on exposed rock plates and the upper surfaces of boulders in alpine heathland, where it can form broad, conspicuous patches in sites subject to wind abrasion, driving rain, snow and intense sun. Iit can also occur on more sheltered, vertical faces. The type collection is from the Hartz Mountains Plateau near Lake Osborne (about 890 m elevation), and additional records span multiple Tasmanian alpine summits and plateaux.^[2]

In these dolerite alpine communities, the yellow crust often forms a visual mosaic with other large, colourful crustose lichens. Kantvilas recorded it growing alongside species such as Trapelia lilacea, several Lecanora species, and with common saxicolous genera including Rhizocarpon, Umbilicaria, Stereocaulon and Placopsis. Some specific associates include Hymenelia gyalectoidea^[4][5] and Rimularia psephota.^[6] Black tufts of the rock-moss Andreaea may also be prominent nearby.^[2] Fertile asci appear to be uncommon in herbarium material (many collections are sterile), so field recognition usually relies on the thick, cracked, lemon-yellow thallus and the minute crater-like surface pits that mark immersed reproductive structures.^[2]