Life habit: non-lichenized, lichenicolous Thallus: absent Apothecia: plane, with a thin margin when young, becoming immarginate and convex, epruinose, up to 0.5 mm in diam. exciple: reddish brown throughout, K-, N+ purple epithecium: pale to dark olive green, K-, N+ pale purple hymenium: pale olive-green with vertical dark streaks, 50-65 µm tall; paraphyses: simple, 2.5-4 µm in diam. below, apically up to 6 µm wide, slightly conglutinated, K-, N+ pale purple hypothecium: dark brown asci: clavate, (12-)15-20 x 35-50 µm, 8-spored ascospores: hyaline, 1-septate, sometimes constricted at septum, broadly ellipsoid, 15-18(-20) x 8-10 µm Pycnidia: not seen Secondary metabolites: none detected. Substrate and ecology: on Lecania over soil or rocks at low elevations in open habitats Host: Lecania dudleyi World and Sonoran distribution: known from two localities in the Channel Islands of southern California and from Baja California Sur. Notes: Toninia subtalparum resembles T. talparum Tim-dal, another lichenicolous species on Lecania, but differs by having a dark brown hypothecium, longer and wider ascospores (respectively 15-18(-20) x 8-10 µm vs. 10-14.5 x 4-5.5) a reddish brown (vs. greenish brown) exciple. Both have a different host range: Toninia talparum is known from Lecania pacifica, L. brunonis, L. fructigena and L. subdispersa, while T. subtalparum is known only from L. dudleyi, growing on soil among stones (type locality) or on soft calcareous outcrops in a grassland (Santa Rosa Island). Another non-lichenized Toninia species with 1-septate ascospores is T. episema (Nyl.) Timdal, that differs from T. subtalparum in its host (Aspicilia calcarea), in having plane to weakly convex apothecia with a +persistent margin, much smaller ascospores (10-13 x 3.5-5.5 µm) and a reddish brown hypothecium. Currently, T. episema is only recorded from Europe.