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Hybridization has long been recognized as common in ferns, but the products of this arguably evolutionary important process have often been ignored in classifications. For example, the recently published Pteridophyte Phylogeny Group classification (PPG I) covered all hierarchical ranks from class to genus but did not include intergeneric hybrids (nothogenera). Here, we provide for the first time a comprehensive evaluation of previously proposed nothogenera in the context of a current phylogeny‐based pteridophyte classification (i.e., PPG I). We find that several nothogenera nested in the orders Osmundales and Polypodiales are supported in the framework of PPG I, but others are superfluous. Five new nothogenera are introduced here for the first time. We also explore the distribution of nothospecies across the pteridophyte phylogeny for the first time. We are unable to reject the hypothesis that species richness and nothospecies diversity are correlated, despite the finding that some temperate lineages contribute more nothospecies than expected whereas several tropical lineages lack them. This pattern could be the consequence of either fundamental differences in modes of speciation in temperate and tropical zones or unequal efforts to record nothospecies. In general, we emphasize the need to take nothogenera into account when proposing generic classifications, but the information provided by the existence of such hybrids needs to be carefully evaluated. Our results underscore the need to report and study hybrids in ferns and lycophytes, especially in biodiversity rich areas. [ABSTRACT FROM AUTHOR]

In this review, we explore our current understanding of the fern and lycophyte diversity occurring in the Eastern Afromontane Biodiversity Hotspot (EABH). The review explores the species diversity of this region in the context of the Afromadagascan pteridophyte diversity based on an exhaustive species list assembled in the synopsis of Afromadagascan pteridophytes published by Roux in 2009. The list was updated by incorporating recent progress in our understanding of the taxonomy and phylogeny of these plants. Evidence for a distinct pteridophyte flora occurring in the East African mountain region was discovered using ordination and clustering analyses. This EABH floras shares links to other Afromadagascan pteridophyte floras such as the one in the tropical lowland forests of central and western Africa. These floras share the dominance of species that preferably occur in humid climates whereas other African pteridophyte floras tend to contain a higher proportion of xeric adapted ferns. The phylogenetic composition of the EABH pteridophyte flora was assessed by comparing global versus local proportion of orders, families, and genera. This analysis revealed distinct patterns that are partly caused by the radiation of Blotiella and Triplophyllum besides selective colonization of species pre-adapted to Afromadagascan climates. In situ speciation in the East African tropical mountains may have contributed to the global diversity of widespread genera such as Asplenium and Pteris. In summary, this is the first comprehensive attempt to assess the pteridophyte diversity of the East African mountains providing the framework for future studies on their conservation, ecology, and evolution. [ABSTRACT FROM AUTHOR]