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.

[2] Phlyctis communis, found in India, also has transversely septate ascospores, but they typically have 7–14 septa and measure 18–33 by 6–9 μm.

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).