This lichen was growing on siliceous rock within a late snow bed in a low alpine heath environment.

[2] The thallus of Lecidea toensbergii is areolate (cracked into small, separate pieces), spreading and can exceed 10 cm (4 in) in diameter.

The areolae (small areas of the thallus) are roughly equal in size, irregular in shape, ranging from angular to rounded, and can be flat to moderately convex.

The thallus has soralia (reproductive propagules) on the margins of the areolae, which are rounded, sharply defined, and white to pale grey, reacting with PD reagent to turn orange.

The disc of the apothecia is flat to slightly convex, black, dull, and faintly white with PD+ orange pruina (a powdery coating).

The excipulum (a cup-like structure around the apothecia) is dark brown throughout or slightly lighter inside, without crystals, and is unreactive to K and KI.

The epihymenium (the upper part of the hymenium) is dark olive brown and contains crystals that do not dissolve in K but react with PD to turn orange.

[2] In 2024, it was reported from Sweden, where it was found on an iron-rich, schistose boulder on a ridge along the northwestern part of the lake Ikesjávrre, near the Norway–Sweden border.