Phylogenetic analysis of some foliicolous lichens collected in Hainan Province, China, revealed a new lineage morphologically similar to Porina but phylogenetically related to Strigulaceae (Dothideomycetes), differing from the latter in ascus type. The monospecific genus Tenuitholiascus gen. nov. is introduced for the single species, T. porinoides sp. nov., which is placed in the new, monogeneric family Tenuitholiascaceae, sister to Strigulaceae in Strigulales. The new taxon closely resembles the genus Porina in external morphology and ascospore type, as well as the thin-walled asci and unbranched paraphyses. Yet, it is entirely unrelated to the latter, which belongs in class Lecanoromycetes in the order Gyalectales.

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.

We employed a molecular phylogenetic approach using five markers (ITS, nuSSU, nuLSU, TEF1-α, and RPB2) to assess potential cryptic speciation in foliicolous members of Strigula s.lat. (Strigulaceae), including the recently segregated genera Phylloporis, Puiggariella, Raciborskiella, Racoplaca, and Serusiauxiella, from tropical areas in Asia, with selected materials from the Neotropics as reference. On the basis of combined molecular and phenotypic datasets, two new species of Racoplaca and 10 new species of Strigula s.str. are described: Racoplaca macrospora sp. nov., R. maculatoides sp. nov., Strigula guangdongensis sp. nov., S. intermedia sp. nov., S. laevis sp. nov., S. microcarpa sp. nov., S. pseudoantillarum sp. nov., S. pseudosubtilissima sp. nov., S. pycnoradians sp. nov., S. sinoconcreta sp. nov., S. stenoloba sp. nov., and S. subtilissimoides sp. nov. In addition, we propose the new combination Phylloporis palmae comb. nov. (≡ =Manaustrum palmae) and we validate the earlier combination Racoplaca melanobapha comb. nov. (≡ Verrucaria melanobapha; Strigula melanobapha). Our data clearly indicate a considerable degree of cryptic diversification in foliicolous representatives of Strigula s.lat., particularly in the presumably widespread taxa Strigula antillarum, S. concreta, S. nitidula, and S. smaragdula. Given that these phylogenetic revisions are thus far limited to few regions, we predict that our findings only represent the proverbial tip of the iceberg in this group of lichenized fungi.

Strigula has traditionally been circumscribed based on morphology, but species delimitation in the genus generally lacks comprehensive analyses. A molecular approach has now been applied to foliicolous material of the genus from tropical areas in China. On the basis of combined phenotyic and genotypic data, two new species are described from southern China: S. acuticonidiarum and S. guangxiensis. Strigula has traditionally been circumscribed based on morphology, but species delimitation in the genus generally lacks comprehensive analyses. A molecular approach has now been applied to foliicolous material of the genus from tropical areas in China. On the basis of combined phenotyic and genotypic data, two new species are described from southern China: S. acuticonidiarum and S. guangxiensis.

A new foliicolous lichen is described from South China. Strigula sinoaustralis is most similar to S. concreta in ascospore dimensions but differs by its white-punctate thallus with entire margins and its longer asci. An analysis of its relationships based on molecular phylogeny is given. Strigula antillarum, S. laureriformis, and S. prasina are reported as new to China.