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Recent studies have uncovered remarkable diversity in Dictyonema s.lat. basidiolichens, here recognized as subtribe Dictyonemateae. This group includes five genera and 148 species, but hundreds more await description. The photobionts of these lichens belong to Rhizonema, a recently resurrected cyanobacterial genus known by a single species. To further investigate photobiont diversity within Dictyonemateae, we generated 765 new cyanobacterial sequences from 635 specimens collected from 18 countries. The ITS barcoding locus supported the recognition of 200 mycobiont (fungal) species among these samples, but the photobiont diversity was comparatively low. Our analyses revealed three main divisions of Rhizonema, with two repeatedly recovered as monophyletic (proposed as new species), and the third mostly paraphyletic. The paraphyletic lineage corresponds to R. interruptum and partnered with mycobionts from all five genera in Dictyonemateae. There was no evidence of photobiont‐mycobiont co‐speciation, but one of the monophyletic lineages of Rhizonema appears to partner predominantly with one of the two major clades of Cora (mycobiont) with samples collected largely from the northern Andes. Molecular clock estimations indicate the Rhizonema species are much older than the fungal species in the Dictyonemateae, suggesting that these basidiolichens obtained their photobionts from older ascolichen lineages and the photobiont variation in extant lineages of Dictyonemateae is the result of multiple photobiont switches. These results support the hypothesis of lichens representing "fungal farmers," in which diverse mycobiont lineages associate with a substantially lower diversity of photobionts by sharing those photobionts best suited for the lichen symbiosis among multiple and often unrelated mycobiont lineages. see also the Perspective by Matthew P. Nelsen. [ABSTRACT FROM AUTHOR]

Traditional taxonomic studies provide only a limited understanding of species richness within a group. Their usefulness for assessing species diversity could also be limited as many lack sufficient sampling and/or fail to integrate different data types for assessing species boundaries. To explore the challenges and limitations of estimating species richness in lichens, we employed an integrative taxonomic approach to elucidate diversification patterns of the genus Sticta (Peltigeraceae) in Puerto Rico. Specimens were collected throughout the island, and a six‐locus dataset was generated to infer phylogenetic relationships among Puerto Rican Sticta and their continental counterparts. Phylogenetic analysis was combined with species delimitation methods and analysis of morpho‐anatomical characters to assess diversity patterns and clarify species‐level taxonomy. We found that Sticta is represented by 16 species in Puerto Rico and that at least 11 (69%) of them are potentially endemic to the island. We describe eight of these in this work: S. borinquensis sp. nov., S. corymbosa sp. nov., S. densiphyllidiata sp. nov., S. guilartensis sp. nov., S. harrisii sp. nov., S. parvilobata sp. nov., S. riparia sp. nov., and S. tainorum sp. nov. These species do not cluster in a monophyletic assemblage but are scattered over the broader Sticta phylogeny, indicating at least eight separate dispersal events. Putative endemic species were found to have close allies occurring in South America. Careful re‐examination of material revealed phenotypical characters that separate most species, suggesting low levels of cryptic diversity. We highlight that integrating molecular methods and other sources of information in species discovery along with comprehensive sampling efforts can greatly enhance our knowledge about diversity patterns in poorly studied groups and regions. Furthermore, species and ecosystems in the Caribbean are being threatened by substantial human‐driven changes (e.g., deforestation, climate change). Consequences of these impacts include reduction in already restricted habitats and potential extinction. We argue that studies analyzing species diversity within a phylogenetic framework could better inform conservation efforts aimed at addressing these challenges. [ABSTRACT FROM AUTHOR]

The early‐successional status of lichens in modern terrestrial ecosystems, together with the role lichen‐mediated weathering plays in the carbon cycle, have contributed to the long and widely held assumption that lichens occupied early terrestrial ecosystems prior to the evolution of vascular plants and drove global change during this time. Their poor preservation potential and the classification of ambiguous fossils as lichens or other fungal–algal associations have further reinforced this view. As unambiguous fossil data are lacking to demonstrate the presence of lichens prior to vascular plants, we utilize an alternate approach to assess their historic presence in early terrestrial ecosystems. Here, we analyze new time‐calibrated phylogenies of ascomycete fungi and chlorophytan algae, that intensively sample lineages with lichen symbionts. Age estimates for several interacting clades show broad congruence and demonstrate that fungal origins of lichenization postdate the earliest tracheophytes. Coupled with the absence of unambiguous fossil data, our work finds no support for lichens having mediated global change during the Neoproterozoic‐early Paleozoic prior to vascular plants. We conclude by discussing our findings in the context of Neoproterozoic‐Paleozoic terrestrial ecosystem evolution and the paleoecological context in which vascular plants evolved. [ABSTRACT FROM AUTHOR]

Foliicolous lichenized fungi (FLF) are widely distributed in tropical forests. The Brazilian Atlantic rainforest, one of the most diverse rainforest biomes, has multiple phyto‐physiognomies. Montane forest fragments or forest refuges, so‐called "Brejos," are located within the semiarid Caatinga in Northeast Brazil. Our objective was to determine the FLF diversity within five Brejos and to analyze their biogeographic affinities within the Neotropics. The FLF biota of the Brejos was compared with that of 21 sites belonging to seven other rainforest biomes, ranging from the Atlantic rainforest in Argentina, to montane rainforests in Ecuador, to the Amazonia basin, and rainforests in Central America. One hundred and fifty‐six species were identified in the Brejos. This biota is most similar to that of the Atlantic rainforest and eastern Amazonia, while that of western Amazonia is more similar to that of the Andes and rainforests in Central America (Chocó). Multiple species identified in the Brejos have a wide distribution in tropical America, and only 11 are potentially endemic. Few other species have also a restricted distribution. The FLF biota of the Chocó and western Amazon is substantially richer than that of eastern Amazon, the Atlantic rainforest and the Brejos. This suggests that the biota of the latter areas is largely a depauperate subset of the Chocó and the western Amazon region. We argue that the major differences between the two large regions are related to the Pleistocene and Pliocene, when paleoclimatic and geological changes caused the isolation of the Brejos and the temporary fragmentation particularly of eastern Amazonia. [ABSTRACT FROM AUTHOR]

The new basidiolichen Multiclavula ichthyiformis Nelsen, Lücking, Umaña, Trest & Will-Wolf is described from Costa Rica. The new species differs from other species of Multiclavula in having a basidiocarp with tomentose stipe and flattened lamina with nonamphigenous hymenium. Molecular sequence data (ITS) confirmed its placement within Multiclavula in the Clavulinaceae (Cantharellales, Agaricomycetes). The new lichen was discovered in a Central American paramo remnant, illustrating the importance of biotic inventories of fungi and lichens to increase our knowledge of the diversity of these groups in endangered tropical ecosystems. The new species was found as part of the TICOLICHEN project in Costa Rica. [ABSTRACT FROM AUTHOR]