Inoderma and related genera in Arthoniaceae with elevated white pruinose pycnidia or sporodochia

The genus Inoderma (Ach.) Gray is lectotypified with Inoderma byssaceum and resurrected for a small group of species in Arthoniaceae with elevated, white pruinose pycnidia, immersed to adnate white pruinose apothecia and a weakly gelatinized hymenium. Inoderma nipponicum is described from Japan, I. afromontanum from Uganda and the European Lecanactis subabietina is transferred to the genus. Sporodophoron is described for a small group of species in Arthoniaceae related to Inoderma but with a unique type of sporodochia instead of pycnidia. Sterile specimens of this new genus resemble species of Tylophoron but differ in the rounded angular to elliptical to short cylindrical, 0-2-septate sporodochial conidia with unevenly thickened walls which are formed apically in zigzag-shaped and occasionally branched chains. Sporodophoron further differs in thallus chemistry and is genetically distinct. Tylophoron americanum and Schismatomma cretaceum are transferred to Sporodophoron, and the new species S. gossypinum from Japan and S. primorskiense from eastern Russia are described. The genus Glomerulophoron is described for a single species from Mauritius, G. mauritiae, differing from Sporodophoron in the tightly coiled chains of sporodochial conidia and being genetically distinct. A phylogenetic tree showing the position of Inoderma, Sporodophoron and Glomerulophoron in Arthoniaceae is presented. A key to all species of Arthoniaceae with sporodochia or elevated white pruinose pycnidia is presented. Arthothelium spectabile, the type of the large heterogeneous genus Arthothelium, is confirmed for the cryptothecioid subclade in Arthoniaceae.