Phlyctis psoromica

Phlyctis psoromica was first scientifically described by Australian lichenologists John Elix and Gintaras Kantvilas. The species is similar to Phlyctis subuncinata, P. sordidae, and P. uncinatae but contains psoromic acid and has smaller ascospores. The type specimen was collected by the first author from the Stockyard Creek Rest Area in Cottan-Bimbang National Park (New South Wales) at an altitude of 685 m (2,247 ft); there, in a wet Eucalyptus forest, it was found growing on Acacia.[2]

The thallus of Phlyctis psoromica is crustose, 40–80 μm thick, and whitish to very pale blue-grey or greenish-grey in colour. It is rimose (cracked), scurfy or furfuraceous (covered in small flakes), and typically forms irregularly spreading patches 3–10 cm (1.2–3.9 in) wide. The lichen lacks isidia and soredia but often becomes ulcerous, eroded and granular near the apothecia. The photobiont is chlorococcoid with more or less spherical cells 6–12 μm wide.[2]

Apothecia are 0.1–0.4 mm wide and usually aggregated in clusters. Ascospores are hyaline, fusiform, and transversely septate, measuring 30–52 μm long and 4–6 μm wide. The lichen's secondary chemistry includes psoromic acid, which is unique to this species among its close relatives.[2]

Phlyctis psoromica is known only from several locations in New South Wales, Australia. It is found on smooth bark of various hosts, such as Doryphora sassafras, Atherosperma moschatum, and species of Elaeocarpus and Pomaderris. The lichen thrives in shaded habitats on the trunks of understory trees in wet upland forests at elevations between 680 and 1,500 m (2,230 and 4,920 ft).[2]