Recent studies of the global diversity of the lichenized fungal family Graphidaceae suggest that there are a large number of species remaining to be discovered. No less than 640 species have been described since 2002, including 175 new species introduced in a collaborative global effort led by Field Museum curators Thorsten Lumbsch and Robert Lücking in a single issue in the journal Phytotaxa. To estimate whether the discovery of 175 new species is a significant step forward in cataloguing extant diversity in this family, the team employed a parametric method to predict global species richness of Graphidaceae using a GIS-based grid map approach. The model employs linear regression between observed species richness and sample score and vegetation composition per grid to predict individual grid species richness, and interpolation of species grid distributions to predict global species richness. The approach resulted in a prediction of 4,330 species of Graphidaceae. Currently, nearly 2,500 species are known in the family, including species not yet formally described. Thus, the model suggests that even after describing 175 species in a single issue of Phytotaxa and with another approximately 140 awaiting publication, the number of species still to be discovered and described is more than 1,800, and much work remains to be done to close this substantial gap. Based on this approach, the team predicts that most of this undiscovered diversity is to be found in Mexico, the northern Andean region, the eastern Amazon and central and southern Brazil, tropical West Africa, continental Southeast Asia, Indonesia, and Papua New Guinea.
The study by Lücking and colleagues is based on two newly assambled, large datasets, which are provided here as online supplements to the published paper:
Online Supplement T1. Species of Graphidaceae (excluding subfamily Gomphilloideae) and their observed distribution in a global grid map spanning tropical and subtropical regions.
Online Supplement T2: GIS-based assessment of vegetation diversity for global grid map spanning tropical and subtropical regions.