Dictyonema s in Eight new species of lichenized Basidiomycota in the genera Acantholichen, Cyphellostereum and Dictyonema s.str. (Agaricales, Hygrophoraceae) from northern South America

Dictyonema s.lat. occurring in the various landmasses that once formed Gondwana correlates with inferred high numbers of species, particularly in northern South America, southern Africa and India (Lücking et al. 2013a,b, Jagadesh-Ram & Singh 2014, Dal Forno 2015, Dal Forno et al. 2016, 2017, Lücking & Timdal 2016). Biogeographic evidence seems to support the hypothesis that the large number of Dictyonema s.lat. species which have a restricted distribution (endemism) in the Neotropics and Paleotropics could have evolved after the breakup of Gondwana (Jörgensen 1983, Stevens 1987, 1991, Audley-Charles & Hallam 1988, Galloway 1988, 1991, Kantvilas 2002, Gibbs 2006, Marcano 2021). However, according to molecular clock studies (Lücking et al. 2013b, 2014b, Dal Forno 2015, Dal Forno et al. 2013, 2017), the divergence of Dictyonema s.lat. could have taken place about 45 Mya during the Eocene, i.e., long after the Gondwana breakup, probably from a non-lichenized ancestor related to Eonema pyriformis (M.P. Christiansen 1960: 108) Redhead, Lücking & Lawrey (Lawrey et al. 2009: 1169) (Lodge et al. 2014). Within the Dictyonema clade, Cyphellostereum diverged rather early, about 35 Mya in the late Eocene, with many species now potentially extinct (Dal Forno 2015, Dal Forno et al. 2013, 2016) while Acantholichen is a recent group of species related to Cora and Corella (Lücking et al. 2013b, 2014b, Dal Forno et al. 2013, 2016).