Rimularia austrolimborina Coppins & Fryday
Lichenologist 38: 105. 2007.
Thallus effuse, or weakly delimited, only occasionally partly delimited by a narrow prothalline zone, deeply rimose areolate, with areoles (0.1–)0.2–0.5(–0.6) mm wide, whitish buff, matt. In section to 300 µm tall; cortex c. 24–30 µm tall, hyaline to dilute straw-brown, composed of ± vertically arranged compacted hyphae c. 2.5 µm wide, sometimes overlain by a c. 5 µm tall epinecral layer; algal layer poorly delimited from the medulla, c. 60–75 µm tall; medulla whitish, containing many mineral fragments from the substratum, I–. Photobiont cells ±globose, 7–12 µm diam.
Apothecia arising from between the areoles, often remaining level with the surface of the thallus, but sometimes emergent or even sessile, rounded or irregularly angular in outline, black, 0.6–1.1(–1.3) mm diam.; margin prominent, radially, deeply cracked, c. 0.15–0.2 mm wide; disc concave, but usually mostly obscured by a raised, convex central ‘umbo’; some apothecia becoming irregularly gyrose-contorted. Exciple cupulate, dark reddish brown [blackish in thick sections], K+ brown-red pigment going into solution, N–, 70–300 µm thick at base, 40–50 µm laterally and 120–200 µm thick at the apex [margin, or ‘labium’]. Hymenium 98–170 µm tall, hyaline or dilute brown-red in uppermost part, I+ blue; epihymenium absent. Hypothecium c. 20–25 µm tall, poorly delimited from the hymenium, dilute brown-red, I–. Asci [few healthy examples seen] clavate, c. 95–110 × 24–27 µm, 8-spored; in K/I with an amyloid outer wall, and an apparently non-amyloid tholus [few good preparations obtained]. Ascospores simple, hyaline or contents dilute brown, ellipsoid, 22–27 × 12–16.5 µm; without an obvious perispore. Paraphyses richly branched, distinctly septate but not moniliform, c. 1–1.5 µm wide.
Conidiomata: no healthy pycnidia seen.
Chemistry. Thallus K+ yellow, C–, KC–, P+ orange, UV–; stictic (major), norstictic (minor) and constictic (minor) acids by TLC.
Ecology and distribution. Known from only two localities near the coast in southern Chile between latitudes 49º52´ and 50º39´S. The holotype specimen has accompanying thalli of Lithographa graphidioides.
Notes. With regard to the general appearance of the apothecia, and of ascospore size, Rimularia austrolimborina closely resembles the Northern Hemisphere R. limborina Nyl. However, the latter has somewhat smaller apothecia (0.3–0.8 mm diam.), and a thinner, more darkly coloured, grey or brown thallus, which lacks lichen substances or rarely contains gyrophoric acid.
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