The genus Coppinsia (lichenized Ascomycetes, Agyriaceae) with the single species C. minutissima sp. nov. is described as new from the British Isles. This minute lichen occurs on soil and bryophytes in metal-rich habitats. It is characterized by a minute thallus, biatorine apothecia with an almost reduced but generally cupulate exciple, slightly branched and apically unthickened paraphyses, a Trapelia-type ascus, and non-septate, ovoid ascospores.