Description.Thallus thin, light grey to ochraceous, continuous, becoming rimose; surface plane, matt or shining; margin indeterminate; prothallus lacking; vegetative propagules absent. Apothecia erumpent, then innate or persistently broadly attached, frequent, often contiguous, to 0.30‑0.40(-0.50) mm in diam., not angular by compression; disc brown, becoming black, persistently plane; thalline margin absent or poorly developed, <0.05 mm wide; excipular ring present when thalline margin absent. Apothecial Anatomy. Thalline exciple absent, or 10‑20 µm wide; cortex absent or ca. 5.0 µm wide; epinecral layer 5‑10 µm deep; crystals absent in cortex and medulla; cortical cells to 4.5-5.0 µm wide, not or very lightly pigmented; algal cells to 7.0‑13.0 µm long; proper exciple hyaline, 5‑15 µm wide laterally, expanding to 10‑20 µm at periphery; hypothecium colourless or yellowish, 40‑60 µm deep; hymenium 60‑85 µm high, not inspersed; paraphyses 2.0‑2.5 µm wide, conglutinate, apices to 3.5‑4.0(-5.0) µm wide, lightly pigmented, forming a reddish-brown epihymenium; asci 55‑65 x 16‑19 µm. Ascospores 8/ascus, Type A development, Pachysporaria‑type II, (14.5-)16.5-17.5(-19.0) x (7.5-)9.0-9.5(-10.5) µm, average l/b ratio 1.8-2.0, lumina irregular, becoming rounded; torus very narrow; walls not ornamented. Pycnidia not seen.
Chemistry. Spot tests all negative; secondary metabolites not tested.
Substrate and Ecology. Corticolous, only recorded on Carya.
Distribution. A new species to North America, known only from duplicate collections in Seminole Co., Florida. Rinodina intrusa probably has a pantropical distribution.
Notes.Rinodina intrusa is characterized by its small, erumpent and persistently broadly attached apothecia, and Pachysporaria-type spores. The species is close to R. maculans, differing primarily in its more broadly ellipsoid spores and generally smaller size. Rinodina intrusa, as understood here, does not correspond to material from South America identified as R. intrusa by Malme (1902) which primarily belongs to R. maculans. Other corticolous specimens of R. intrusa listed by Malme belong to R. connectens. Saxicolous specimens of R. intrusa from South America (Malme 1902 and Lich. Austroamericani 72 ‑ H) belong to R. viridis Mull. Arg., a species also characterized by Pachysporaria‑type spores.
Specimens examined. BRAZIL. SANTA CATARINA. Ihla de Santa Catarina, 1980, K. Kalb, Lich. Neotropici 117, 118 (CANL). CUBA. ORIENTE. Near Santiago, H.A. Imshaug 24641. GRAND CAYMAN. Near 'Castle', H.A. Imshaug 24554 (both MSC). U.S.A. FLORIDA. Seminole Co., Sanford, S. Rapp 229 (FH).