[1] Uniquely identified by its sorediate form—a feature not observed in other Rhizoplaca species—it was discovered in Ontario, Canada, specifically within the Ouimet Canyon Provincial Park.

[3] Rhizoplaca ouimetensis has a crustose thallus that is made up of areoles (small, angular sections) that can spread irregularly to cover diameters of several centimetres.

These areoles are typically convex to bullate (blister-like) or pulvinate (cushion-shaped), occasionally presenting a minutely shield-like (peltate) appearance.

This cortex is made up of densely branched, mostly vertically aligned (anticlinal) hyphae, which are fungal filaments with thin walls and short cylindrical spaces inside (lumina).

Another distinctive feature of R. ouimetensis is its well-developed upper cortex and a medulla densely packed with calcium oxalate crystals, setting it apart from the aforementioned Lecanora species.

Except for L. jamesii, which also contains usnic acid along with 2-O-methylsulphurellin, atranorin, and chloroatranorin, the other Lecanora species include zeorin in addition to yellow pigments and possibly other compounds, further differentiating them from R. ouimetensis.

[2] Rhizoplaca ouimetensis is found exclusively in the Lake Nipigon ecoregion of Thunder Bay District, growing on exposed, near-vertical diabase sills amidst a boreal forest backdrop.