Arthonia molendoi
≡*Tichothecium molendoi Heufl. ex Frauenf., in F.G.C. Arnold, Verhandl. Zool.-bot. Ges. Wien 14: 462 (1864).
Description : Lichenicolous. Apothecia rounded, 0.1–0.3 mm diam., strongly convex, dull, black or dark-brown. Hymenium I+ red, IKI+ blue, to 40 μm tall, colourless, with upper parts brownish to blackened. Paraphysoids branched, end cells enlarged to 4 μm diam., and brownish to brown-black. Hypothecium colourless. Ascospores, colourless, 1-septate with somewhat unequal cells, constricted at septum, 8–12 × 4–6 μm.
S: Otago. On high-alpine schist rocks and occasionally also on concrete walls and fence posts in alpine habitats. Known also from Greenland, Europe, Macaronesia, Asia, North America and Antarctica (Alstrup & Hawksworth 1990; Goward et al. 1996; Alstrup & Cole 1998; Cole & Hawksworth 2001; Øvstedal & Lewis Smith 2001; Triebel & Scholz 2001; Hafellner et al. 2002; Nimis & Martellos 2003).
Bipolar
Hosts : Caloplaca saxicola and Xanthoria elegans.
Illustration : Gams et al. (2004: 357, fig. 17.6).
* Arthonia molendoi is characterised by: the lichenicolous habit; black apothecia 0.1–0.3 mm diam.; pale hypothecium; distinct paraphyses; I+ wine-red reaction of the hymenium; black epithecium; 1-septate ascospores with unequal cells, 8–12 × 4–6 μm.
