A quantitative prediction of global species richness in the lichenized family Trypetheliaceae employing a grid method previously used in similar approaches for the family Graphidaceae and the genus Cora (Hygrophoraceae) is provided. 421 currently known taxa were used as a base for the calculation and we predict a total of nearly 800 species, corresponding to an increase of almost 100%. Most of the unrecognized taxa are predicted to occur in the Neotropics, which have the highest known species richness. The Palaeotropics are less diverse. In contrast to Graphidaceae, which are mostly confined to rainforests, Trypetheliaceae show substantial species richness in dry forest and savannah ecosystems, and future collection efforts should take well-preserved areas representing such ecosystems into consideration.
