Phylogenetic classification and generic delineation of<i>Calyptosphaeria</i>gen. nov.,<i>Lentomitella</i>,<i>Spadicoides</i>and<i>Torrentispora</i>(<i>Sordariomycetes</i>)

Abstract

The genus <i>Ceratostomella</i> has a long history of taxonomic confusion. While species with evanescent asci have been transferred to the <i>Microascales</i> and <i>Ophiostomatales</i>, the taxonomic status of species with persistent asci has not been completely resolved. In previous studies using DNA sequence data, cultures and morphology, several <i>Ceratostomella</i> spp. were allocated in 13 genera in the <i>Eurotiomycetes</i> and <i>Sordariomycetes</i>. In our study, the systematics of the remaining <i>Ceratostomella</i> spp. with persistent asci is revisited with new collection data, cultures and phylogeny based on novel DNA sequences from six nuclear loci. Bayesian inference and Maximum Likelihood analyses support the monophyly of several wood-inhabiting species formerly classified in <i>Ceratostomella</i> and other unknown morphologically similar taxa and their division into four genera, i.e. <i>Lentomitella</i>, <i>Spadicoides</i>, <i>Torrentispora</i> and the newly described <i>Calyptosphaeria</i>. This robust clade represents the order <i>Xenospadicoidales</i> in the <i>Sordariomycetidae</i>. Comparative analysis of the ITS2 secondary structure revealed a genetic variation among <i>Lentomitella</i> isolates; 11 species were recognised, of which five are newly introduced and two are new combinations. Other taxonomic novelties include four new species and eight new combinations in <i>Calyptosphaeria</i>, <i>Spadicoides</i>, and <i>Torrentispora</i>. Molecular data suggest that <i>Spadicoides</i> is polyphyletic. The core of the genus is positioned in the <i>Xenospadicoidales</i>; <i>Spadicoides</i> s. str. is experimentally linked with sexual morphs for the first time. Based on DNA sequence data, the monotypic genera <i>Xenospadicoides</i> and <i>Pseudodiplococcium</i> are reduced to synonymy under <i>Spadicoides</i>, while <i>Fusoidispora</i> and <i>Pseudoannulatascus</i> are synonymised with <i>Torrentispora</i>. Members of the <i>Xenospadicoidales</i> inhabit decaying wood in terrestrial and freshwater environments and share a few morphological characters such as the absence of stromatic tissue, ascomata with a cylindrical or rostrate neck, similar anatomies of the ascomatal walls, thin-walled unitunicate asci with a non-amyloid apical annulus, disintegrating paraphyses, usually ellipsoidal to fusiform ascospores and holoblastic-denticulate or tretic conidiogenesis. Revised <i>Ceratostomella</i> spp. with persistent asci are listed and the taxonomic status of each species is re-evaluated based on revision of the holotype and other representative material, published details and available phylogenetic data.