Phylogenetic delimitation of Apiospora and Arthrinium

In the present study six species of Arthrinium (including a new taxon, Ar. crenatum) are described and subjected to phylogenetic analysis. The analysis of ITS and 28S rDNA, as well as sequences of tef1 and tub2 exons suggests that Arthrinium s. str. and Apiospora represent independent lineages within Apiosporaceae. Morphologically, Arthrinium and Apiospora do not seem to have clear diagnostic features, although species of Arthrinium often produce variously shaped conidia (navicular, fusoid, curved, polygonal, rounded), while most species of Apiospora have rounded (face view) / lenticular (side view) conidia. Ecologically, most sequenced collections of Arthrinium were found on Cyperaceae or Juncaceae in temperate, cold or alpine habitats, while those of Apiospora were collected mainly on Poaceae (but also many other plant host families) in a wide range of habitats, including tropical and subtropical regions. A lectotype for Sphaeria apiospora (syn.: Ap. montagnei, type species of Apiospora) is selected among the original collections preserved at the PC fungarium, and the putative identity of this taxon, found on Poaceae in Mediterranean lowland habitats, is discussed. Fifty-five species of Arthrinium are combined to Apiospora, and a key to species of Arthrinium s. str. is provided. Citation: Pintos Á, Alvarado P (2021). Phylogenetic delimitation of Apiospora and Arthrinium. Fungal Systematics and Evolution 7: 197-221. doi: 10.3114/fuse.2021.07.10.