A world-wide key to the thelotremoid Graphidaceae, excluding the Ocellularia-Myriotrema-Stegobolus clade

In the course of an ongoing systematic and taxonomic revision of the lichen family Graphidaceae (including Thelotremataceae), we present world-wide keys to the currently accepted thelotremoid genera and species, excluding the columellate taxa and their relatives of the Ocellularia-Myriotrema-Stegobolus clade (Melanotrema, Myriotrema, Ocellularia, Ocellularia clandestina group, Redingeria, Stegobolus), which will be treated in a forthcoming paper. The keys include all genera and species with chroodiscoid, lepadinoid, and topeliopsidoid apothecia and other taxa featuring periphysoids or fibrils, and their relatives. Taxa keyed out to genus and species level are Acanthotrema, Chapsa, Chroodiscus, Diploschistes, Fibrillithecis, Gyrotrema, Leptotrema, Leucodecton, Melanotopelia, the ‘Ocellularia’ cruentata group, Pseudoramonia, Reimnitzia, Schizotrema, Thelotrema, Topeliopsis and Wirthiotrema. Over 260 species are treated, including a few yet unnamed taxa. The following taxonomic and nomenclatural novelties are introduced: Acanthotrema frischii Lücking sp. nov., Chapsa aggregata (Hale) Sipman & Lücking comb. nov., C. albida (Nyl.) Lücking & Sipman comb. nov.; C. albomaculata (Sipman) Sipman & Lücking comb. nov., C. boninensis (Tat. Matsumoto) Rivas Plata & Mangold comb. nov., C. elabens (Müll. Arg.) Rivas Plata & Mangold comb. nov., C. imperfecta (Hale) Rivas Plata & Lücking comb. nov., C. laceratula (Müll. Arg.) Rivas Plata & Lücking comb. nov., C. magnifica (Berk. & Broome) Rivas Plata & Lücking comb. nov., C. meghalayensis (Patw. & Nagarkar) Lumbsch & Divakar comb. nov., C. meridensis (Kalb & Frisch) Lücking, Lumbsch & Rivas Plata comb. nov., C. mirabilis (Zahlbr.) Lücking comb. nov., C. neei (Hale) Mangold & Lücking comb. nov., C. paralbida (Riddle) Rivas Plata & Lücking comb. nov., C. pseudoexanthismocarpa (Patw. & C. R. Kulk.) Rivas Plata & Lücking comb. nov., C. pulvereodisca (Hale) Rivas Plata & Mangold comb. nov., C. scabiomarginata (Hale) Rivas Plata & Lücking comb. nov., C. waasii (Hale) Sipman & Lücking comb. nov., Fibrillithecis argentea (Müll. Arg.) Rivas Plata & Lücking comb. nov., F. carneodisca (Hale) Rivas Plata & Lücking comb. nov., F. confusa Lücking, Kalb & Rivas Plata spec. nov., F. diminita (Hale) Rivas Plata & Lücking comb. nov., F. eximia (R. C. Harris) Rivas Plata & Lücking comb. nov., F. fissurata (Nagarkar & Hale) Rivas Plata & Lücking comb. nov., F. gibbosa (H. Magn.) Rivas Plata & Lücking comb. nov., Leucodecton desquamescens (Vain.) Lücking comb. nov., L. oxysporum (Redinger) Lücking comb. nov., Schizotrema cryptotrema (Nyl.) Rivas Plata & Mangold comb. nov., Thelotrema patwardhanii (Hale) Rivas Plata & Mangold comb. nov., Topeliopsis guaiquinimae (Sipman) Rivas Plata & Mangold comb. nov., and T. tuberculifera (Vain.) Rivas Plata & Mangold comb. nov. Using the examples of Fibrillithecis halei s. lat., Leucodecton compunctellum s. lat., and Thelotrema monosporum s. lat., we show how difficult species complexes can be flexibly treated in a key, allowing for either a broad concept or the distinction of several individual taxa.