It occurs at high altitudes in Argentina, Ecuador, and Peru, where it grows on acidic rocks in open habitats.

[3] The species epithet lambi honours polar explorer and lichenologist Elke Mackenzie (formerly Lamb),[4] who collected the type specimen from the Tafí del Valle (Tucumán Province, Argentina, in 1947.

There, in an alpine pasture at an altitude of 3,100 m (10,200 ft), it was found growing on a block of schistose rock.

[1] Placomaronea lambii has a distinct rosette-like form, comprising numerous brownish-yellow lobes that can be multi-lobed and overlapping.

Its ascospores are narrowly ellipsoid to nearly oblong, and typically measure 9.0–12.0 long by 3.0–4.5 μm wide.