Placopsis perrugosa is a saxicolous (rock-dwelling), placodioid lichen in the family Trapeliaceae.

[2] It was formally described as a new species in 1867 by Finnish lichenologist William Nylander, originally as a member of the genus Lecanora.

[3] After the retreat of the Glaciar Frías in the Patagonian Andes, Argentina, Placopsis perrugosa dominated the pioneer stage on newly exposed rock outcrops.

This was followed by a mid-successional stage, in which a lichen-moss mat was dominated by the moss Racomitrium lanuginosum, providing the foundation for a larger diversity of vascular plants in the final successional stage.

[4] Like other members of genus Placopsis, P. perrugosa is a fast-growing crustose lichen; this allows them to dominate as early colonisers on snow-free moraines of exposed land surfaces.