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Arthonia farinacea (H. Olivier) R. Sant.
Family: Arthoniaceae
Arthonia farinacea image
Life from: lichenicolous, on soredia of Ramalina spp. Thallus: not apparent photobiont: absent Ascomata: superficial on the host soredia, ±round, up to 0.25 mm wide disc: black, with rough surface, convex epihymenium: brown, 10-20 µm thick; hyphal tips with pigment caps, up to 4 µm thick hymenium: hyaline, 30-35 µm thick; paraphysoids branched and anastomosed, c. 1 µm thick; subhymenium: pale brown, 40-60 µm thick asci: broadly clavate, 24-28 x 12-14 µm, 8-spored ascospores: hyaline, (1-)2-septate, narrowly ellispoidic, 12-16 x 3.5-4.5 µm, without an epispore Pycnidia: not found Chemical reactions: ascomatal gels I+red, KI+ blue, with KI+ blue rings-structure. Substrate and ecology: see host World distribution: probably throughout the range of its host, but likely overlooked Sonoran distribution: southern California (San Luis Obispo Co.).