Description.Thallus typically thin, sometimes thick, citrine, continuous or rimose; surface plane, or rugose in thicker thalli, matt; margin indeterminate; prothallus lacking; vegetative propagules absent. Apothecia erumpent and subinnate at first, remaining broadly attached, frequent, commonly contiguous, to 0.50‑0.85 mm in diam.; disc black, persistently plane; thalline margin concolourous with thallus, entire, sometimes becoming flexuose, persistent, 0.05‑0.10 mm wide; excipular ring absent or confluent. Apothecial Anatomy. Thalline exciple 30‑85 µm wide; cortex; 5‑10 µm wide, epinecral layer 10‑15 µm wide; crystals in cortex and medulla; cortical cells to ca. 4.0 µm wide, not pigmented; algal cells to 8.0‑11.0 µm long; proper exciple 10‑15 µm wide laterally, expanding to 15‑25 µm above, frequently pigmented yellowish‑brown; hypothecium hyaline or pigmented like exciple, 35‑80 µm deep; hymenium 90‑115 µm high, not inspersed; paraphyses 1.5‑2.0 µm wide, conglutinate, apices to 2.5‑4.0 µm wide, lightly pigmented, immersed in dispersed pigment forming a red‑brown epihymenium; asci 60‑85 x 18‑33 µm. Ascospores 8 spores/ascus, Type A development, Pachysporaria‑type I, (18.0-)22.5-24.5(-29.0) x (9.0-)11.5‑13.0(-15.5) µm, l/b ratio 1.8-2.1, lumina irregularly rounded at first (subpolygonal), lacking well defined canals, with persistently thick walls; torus narrow, darkly pigmented; walls not ornamented. Pycnidia not seen.
Chemistry. Spot tests, K+ gold-yellow, C‑, KC-, P‑; secondary metabolites, thiomelin and zeorin (major), with 2‑dechlorothiomelin (minor), 4‑dechlorothiomelin (trace), 5,7‑dichloro-8-hydroxy‑2‑methoxy‑1,3‑dimethylxanthone (minor or trace), 5,7‑dichloro‑2,8‑dihydroxy-1,3-dimethylxanthone (trace) (Elix, personal communication).
Substrate and Ecology. Corticolous and lignicolous. Collected on Quercus alba and Q. velutina but substrate rarely reported.
Distribution. A pantropical species (Zahlbruckner 1931), limited to Florida and coastal regions of the Gulf states in North America. shows that the species was once more widely distributed than it currently is. Together with R. colobinoides and R. intrusa, this species represents the tropical Rinodina flora in North America.
Notes. Rinodina lepida is well characterized by the citrine pigmentation of the thallus and medulla, its erumpent apothecia, and Pachysporaria-type I spores. Rinodina chrysomelaena, a saxicolous species with a similarly pigmented thallus, is distinguished by the presence of secalonic acid W, narrowly attached apothecia and Physcia‑type spores.
This species is closely related by both spore type and chemistry to the saxicolous R. thiomela (Nyl.) Müll. Arg. and R. xanthomelana Müll. Arg., two other tropical species. The latter species is here reported for the first time from the western hemisphere (Jamaica, Imshaug 13920, 13944, 13995 MSC).
Specimens examined. U.S.A. ALABAMA. Mobile Co., Mobile, C. Mohr (US); 1880, C. Mohr (FH). FLORIDA. Alachua Co., Gainsville, H.W. Ravenel (BM); H.W. Ravenel 64 (FH); Broward Co., South Wind, J.D. Smith (US); Duval Co., Jacksonville (FH); Lake Co., Eustis, G.S. Mead (FH, US); Lee Co., Caloosahatchee River, 1879, R.A. Austin (FH); Marion Co., Hughes Island, R.C. Harris 1995 (MIN, MSC); 1998 (CANL, MSC); 2019 (MSC); Sarasota Co., Myakka River State Park, R.C. Harris 2609b (MSC); Seminole Co., Sanford, 1910, S. Rapp (US); 1919, S. Rapp (FH, US); 1924, S. Rapp (FH); Wakulla Co., Spring Creek, S. Apfelbaum 347 (MOR). GEORGIA. Ware Co., Mims Island, C.M. Wetmore 64563 (MIN). LOUISIANA. St. Landry Par., Opelousas, A.B. Langlois 131 (US).