A world monograph of the lichen genus Gyalectidium (Gomphillaceae)

Seventeen new species of Gyalectidiumhave been discovered in various parts of the world, and those unexpected findings formed the starting point for a survey of the taxonomy and ecogeography of the genus. The following species are described as new in this paper: G. areolatumFerraro & Lucking (Neotropics), G. atrosquamulatumLucking & Kalb (Kenya), G. australeLücking (Australia), G. conchiferumLücking& Wirth (Chile), G. den‐ticulatumLücking (Costa Rica), G. fantasticumFerraro & Lücking (Neotropics), G. flabellatumSérus. (Australasia), G. fuscumLücking & Sérus. (Africa and Papua New Guinea), G. gahavisukanumSérus. (Papua New Guinea), G. kenyanumLücking & Kalb (Kenya). G. laciniatumLücking (Costa Rica), G. maracaeLücking (Neotropics), G. membranaceumSérus. & Lücking (Canary Islands), G. minusSérus (Canary Islands and southern Italy), G. novoguineenseSérus. (Australasia), G. puntilloiSérus. (south‐west Europe), and G. verruculosumSérus. (Australasia). Calenia microcarpaVzda [Syn.: Bullatina microcarpa(Vda) Brusse] is included in Gyalectidiumas G. microcarpum(Vzda) Lücking, Sérus. & Vzda comb, nov., and G. catenulatum(Cavalc. & A. A. Silva) Ferraro, Lücking & Sérus. is treated as a species different from G. ftlicinum. Gyalectidium corticolaHenssen is transferred to Caleniaas Calenia corticola(Henssen) Ferraro, Lücking & Sérus. comb. nov. A key to all 29 accepted species of Gyalectidiumis provided. The infrageneric phylogeny is constructed by means of a phenotype‐based cladistic analysis, and the systematic affinities of the genus are discussed, accompanied by notes on the distribution and ecology of the species. Apothecia are not yet known in several species, including new ones.