Reallocation of foliicolous species of the genus Strigula into six genera (lichenized Ascomycota, Dothideomycetes, Strigulaceae)

Abstract

Strigula sensu lato has been previously defined based on phenotype characters as a rather broad genus including tropical to temperate species growing on a wide array of substrata. In this study, based on a multilocus phylogenetic approach, we show that foliicolous species form six well-delimited clades that correlate with diagnostic phenotype features, including thallus morphology, carbonization of the involucrellum and excipulum, ascospore dimensions, and type of macroconidia. Given the topology, with five of the six clades emerging on long stem branches, and the strong phenotypical differentiation between the clades, we recognize these at the genus level, making mostly use of previously established genus names. Four genera, namely Phylloporis, Puiggariella, Raciborskiella, and Racoplaca, are resurrected for the S. phyllogena, S. nemathora, S. janeirensis, and S. subtilissima groups, respectively, whereas one new genus, Serusiauxiella gen. nov., is introduced for a novel lineage with peculiar macroconidia. The only sequenced non-foliicolous species, S. jamesii, is not closely related to these six foliicolous lineages but clusters with Flavobathelium and Phyllobathelium, revealing it as an additional undescribed genus-level lineage being treated elsewhere. Within the new genus Serusiauxiella, three new species are described: Serusiauxiella filifera sp. nov., S. flagellata sp. nov., and S. sinensis sp. nov. In addition, ten new combinations are proposed: Phylloporis austropunctata comb. nov., P. radiata comb. nov., P. vulgaris comb. nov., Puiggariella confluens comb. et stat. nov., P. nemathora comb. nov., P. nigrocincta comb. nov., Racoplaca maculata comb. nov., R. melanobapha comb. nov., R. transversoundulata, and R. tremens comb. nov. We also report on a peculiar, previously unrecognized growth behaviour of the macroconidial appendages in Strigula s.lat.