Lecanora cateilea is a member of the L. pallida group which includes species with a pruinose disc and an ecorticate apothecial margin (see Imshaug & Brodo 1966, Magnusson 1932). L. cateilea is distinguished by the polysporous asci and a PD+ Sulphuric yellow apothecial margin caused by the presence of psoromic acid. The present specimens contained atranorin and zeorin in the thallus and the apothecia; psoromic acid (with satellite substances) was found only in the apothecia. L. intumescens is another, more widespread and common species in this group. Some specimens, mainly from central Norway which were studied for comparison had apothecia up to about 2 mm diam. (up to 1 mm in L. cateilea), a distinct, thick and often prominent margin, and octosporous asci. Chemically the two species proved to be similar, but in apothecia of L. intumescens an unidentified major substance - "intumescens unknown" - occurred, which may prove to be diagnostic. It is represented by UV+ vivid white spots on untreated plates, and the Rf-classes are A:4, B:5, C:5. "Intumescens unknown" and psoromic acid overlap in solvent C and partly in solvent A; in solvent B it yields a spot above that of psoromic acid.

In Norway L. cateilea has been collected on smooth bark of Alnus incana and Sorbus aucuparia at altitudes between 130 and 600 m. It seems to prefer somewhat shaded habitats. L. cateilea is a northern species (Magnusson 1932); in Scandinavia it was previously known from Varmland to Lule Lappmark (Santesson 1984).