Caloplaca oleicola (J. Steiner) van den Boom & Breuss
in van den Boom & Etayo, Mycotaxon, 56: 131, 1995. Basionym: Blastenia oleicola J. Steiner - Verh. zool.-bot. Ges. Wien, 61: 61-62, 1911.
Distribution: N - Lig (van den Boom & Etayo 1995).
Description: Thallus crustose, thinly episubstratic, white to grey-white. Apothecia biatorine, sessile, 0.2-0.4 mm across, with a black, epruinose disc and a thin proper margin. Proper exciple prosoplectenchymatous, brown to grey brown in outer part, colourless within, the pigmented parts K+ violet, N+ orange-red; epithecium grey-brown, K+ strongly violet, N+ orange-red; hymenium colourless, 45-75 µm high, K/I+ blue; paraphyses simple or sparingly branched in upper part, 1-1.5 µm thick at base, the apical cells up to 3 µm wide; hypothecium colourless. Asci 8-spored, clavate, functionally unitunicate, apically thickened with a broad internal beak, the inner part of apex and external cap I+ blue, Teloschistes-type. Ascospores 2-celled, polarilocular, hyaline, ellipsoid, 11-15 x 6-8 µm, the equatorial thickening (“septum”) 4-7 µm; lumina of immature spores sometimes sandglass-shaped. Photobiont chlorococcoid. Spot tests: thallus K-, C-, KC- P-. Chemistry: exciple and epithecium with unidentified anthraquinones.
Note: this is one of the few black-fruited epiphytic caloplacoid lichens. The type material is from Liguria. I have also seen samples from Greece and Turkey: it could be more widespread in the Mediterranean Region, but it is certainly not common in Italy. The species is included in the Italian red list of epiphytic lichens as “Data Deficient” (Nascimbene & al. 2013c).