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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 in a single issue in this journal. These findings suggest that the largest family of tropical crustose lichens may have an even higher number of species than Parmeliaceae. To estimate whether the discovery of 175 new species is a significant step forward in cataloguing extant diversity in this family, we 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. We also applied a non-parametric species-area curve approach and non-parametric species richness estimators (Chao, Jackknife, Bootstrap) to compare the results from the different methods. Our approach resulted in a prediction of 4,330 species of Graphidaceae, including approximately 3,500 (sub-)tropical species in the core subfamilies Fissurinoideae, Graphidoideae, Redonographoideae, plus 125 species restricted to extratropical regions (outside the zone between 30° northern and 30° southern latitude) and 700 species in subfamily Gomphilloideae. Currently, nearly 2,500 species are known in the family, including species not yet formally described. Thus, our model suggests that even after describing 175 species in this issue 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 our approach, we predict 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 Cladia aggregata complex is one of the phenotypically most variable groups in lichenized fungi, making species determination difficult and resulting in different classifications accepting between one to eight species. Multi-locus DNA sequence data provide an avenue to test species delimitation scenarios using genealogical and coalescent methods, employing gene and species trees. Here we tested species delimitation in the complex using molecular data of four loci (nuITS and IGS rDNA, protein-coding GAPDH and Mcm-7), including 474 newly generated sequences. Using a combination of ML and Bayesian gene tree topologies, species tree inferences, coalescent-based species delimitation, and examination of phenotypic variation we assessed the circumscription of lineages. We propose that results from our analyses support a 12 species delimitation scenario, suggesting that there is a high level of species diversity in the complex. Morphological and chemical characters often do not characterize lineages but show some degree of plasticity within at least some of the clades. However, clades can often be characterized by a combination of several phenotypical characters. In contrast to the amount of homoplasy in the morphological characters, the data set exhibits some geographical patterns with putative species having distribution patterns, such as austral, Australasian or being endemic to Australia, New Zealand or Tasmania.

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Phylogenetic relationships of the genera Cladia and Heterodea were reconstructed using a combined dataset of nuclear ITS, nuclear LSU and mitochondrial SSU rDNA sequences. Based on different analyses (Bayesian approach, maximum parsimony, maximum likelihood), the ingroup (Cladia + Heterodea) is strongly supported as monophyletic. Pilophorus strumaticus has a well supported sister–group relationship to the ingroup and together they form a sister group with a well–supported clade, which includes Metus conglomeratus and Pycnothelia papillaria. The Shimodaira–Hasegawa test and the ELW test significantly rejected monophyly of Cladia excluding Heterodea. Within Cladia three main clades can be distinguished which share morphological and chemical characters. The position of the foliose genus Heterodea within the fruticose Cladia is supported by anatomical and chemical characters. The species of clade II that includes two Cladia species and Heterodea share a similar type of upper cortex and two–layered medulla with an inner or lower medulla consisting of dark pigmented, thick–walled hyphae. Our phylogenetic estimate and the anatomical studies indicate that the foliose thallus of Heterodea originated from pseudopodetia of Cladia. It is discussed that the species currently classified in Cladia and Heterodea need to be placed in the same genus.

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