Morph. et Anat.: 117 (1909).

Synonyms: Index Fungorum

Protolog: Data lacking. Acarospora rhabarbarina nom. nov. pro Lecanora bella Nyl. non Lecanora bella Ach., Lichenogr. Univ.: 398 (1810).

Type locality: Chile, Quilmenco, Gay s.n. (PC [sheet 1]). Lectotype designated by Knudsen et al. (2008: 9).

Barcode: Data lacking.

Coordinates: Data lacking.

Thallus: crustose, areolate, verrucose or squamulose. Areoles, verrucae or squamules dispersed or contiguous, 0.5-2.0 mm wide, ca. 0.5-0.7 thick, round and convex to flat and angular, rim down-turned to undulate in some squamules, propagating by vegetative division; broadly attached, areoles in well-developed specimens becoming stipitate and squamulose. Upper surface usually glossy yellow, smooth but becoming fissured, rarely pruinose; syncortex indistinct to 15 µm thick, eucortex 50-130 µm thick. Lower surface corticate, white to yellow or brownish. Algal layer uniform and even of becoming irregular and interrupted by hyphal bundles in well-developed and dividing specimens (Magnusson, 1929a & b; Hue 1909). Apothecia one to three per areole or verruca, but contiguous thalli may comprise multiple units with multiple apothecia, ultimately forming pin-wheel like agglomerations of reduced apothecia (as in type of A. malmeana); disc immersed, deep reddish brown to reddish black (only one specimen seen with pale yellowish apothecia forming pinwheel agglomerations in center), ca. 0.2-0.6 mm in diam., round to rarely slit-like, epruinose, rough. Hymenium 90-110 µm tall, hyaline to pale yellowish. Epihymenium conglutinated in reddish to yellowish brown pigmented gel. Paraphyses ca. 2 µm wide at mid-level, sometimes branching, apices expanded to 3-4 µm. Asci 75-90 x 15-20 µm, clavate; ascospores 100-200 per ascus, broadly ellipsoid, 4-6 x 2-3 µm. Pycnidia unknown (Knudsen et al. 2008: 9).

Photobiont: Trebouxioid green alga.

Chemistry: Spot tests negative. Epanorin (major or trace), and/or rhizocarpic acid (major or trace), + conepanorin (minor), + conrhizocarpic acid (minor), + vulpinic acid (trace). The two chemotypes do not appear to exhibit any differences in geographical distribution, substrate preference or morphological expression (Knudsen et al. 2008: 9).

Ecology: On exposed volcanic and acidic rocks and adjacent soil above 900 meters elevation.

Molecular data: Genbank

Distribution: Argentina, Bolivia, Chile, Peru, rare in Arizona and California. Database

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