Rimularia maculata Fryday
Biblioth. Lichenol. 88: 142. 2004.
Thallus widespreading, usually in a mosaic of other crustose species, c. 0.3 mm thick; areolate; areoles 0.2-0.5 mm across, pale brown with black ridges of carbonized material (dark brown in section) giving the thallus an overall dark brown appearance; medulla I+ violet. Photobiont chlorococcoid, cells globose, 8.5-12 µm diam.
Apothecia black, lecideine, orbicular, 0.4-0.5 mm diam, immersed in the thallus with concave disc (pale brown when wet) and thick, slightly raised carbonaceous margin 0.08-0.1 mm wide. Exciple massively developed, dark brown, carbonized, cupular. Hypothecium hyaline, 85-100 µm, of mostly vertically orientated hyphae. Hymenium hyaline, I+ blue, 70-85 µm thick; epihymenial zone 15-20 µm, dilute olive-brown (K+ more dilute). Paraphyses slender, 1.5-2.0 µm wide, richly branched and anastomosing, scarcely swollen at the apex (to 3.0 µm) without a pigmented cap. Asci cylindrical-clavate, 50-60 x 17-20 µm, Rimularia -type. Ascospores, hyaline, simple, (11-)12-15(-18) x 6.5-8(-9) µm.
Conidiomata not observed.
Chemistry: K—, C—, Pd—. No substances detected by TLC
Distribution & Ecology: Known only from siliceous rocks on Campbell Island and the Auckland Islands.
Notes: The massively developed exciple of this species is probably not a significant character, as it is frequent in other species in the area. The same applies to the innate apothecia. It is probable that if this species occurs in more temperate areas it will have sessile apothecia with a relatively thin margin.
Rimularia maculata is easily identified by the presence of dark ridges of carbonized material on its thallus. However, even in the absence of these, the species is still separated from all other members of the genus by its I+ violet medulla and lack of lichen substances in the thallus (HERTEL & RAMBOLD 1990).
Associated lichens include Lecanora physcielloides (see above), Lecidea lygomma, Lecidella sp., and Placopsis sp.
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