Nomenclatural type definitions are one of the most important concepts in biological nomenclature. Being physical objects that can be re-studied by other researchers, types permanently link taxonomy (an artificial agreement to classify biological diversity) with nomenclature (an artificial agreement to name biological diversity). Two proposals to amend the International Code of Nomenclature for algae, fungi, and plants (ICN), allowing DNA sequences alone (of any region and extent) to serve as types of taxon names for voucherless fungi (mainly putative taxa from environmental DNA sequences), have been submitted to be voted on at the 11th International Mycological Congress (Puerto Rico, July 2018). We consider various genetic processes affecting the distribution of alleles among taxa and find that alleles may not consistently and uniquely represent the species within which they are contained. Should the proposals be accepted, the meaning of nomenclatural types would change in a fundamental way from physical objects as sources of data to the data themselves. Such changes are conducive to irreproducible science, the potential typification on artefactual data, and massive creation of names with low information content, ultimately causing nomenclatural instability and unnecessary work for future researchers that would stall future explorations of fungal diversity. We conclude that the acceptance of DNA sequences alone as types of names of taxa, under the terms used in the current proposals, is unnecessary and would not solve the problem of naming putative taxa known only from DNA sequences in a scientifically defensible way. As an alternative, we highlight the use of formulas for naming putative taxa (candidate taxa) that do not require any modification of the ICN.

Phylogenetic analyses of a combined DNA data matrix containing ITS, LSU, rpb2 and tub2 sequences of representative Xylariales revealed that the genus Barrmaelia is a well-defined monophylum, as based on four of its described species (B. macrospora, B. moravica, B. oxyacanthae, B. rhamnicola) and the new species B. rappazii. The generic type of Entosordaria, E. perfidiosa, is revealed as the closest relative of Barrmaelia, being phylogenetically distant from the generic type of Clypeosphaeria, C. mamillana, which belongs to Xylariaceae sensu stricto. Entosordaria and Barrmaelia are highly supported and form a distinct lineage, which is recognised as the new family Barrmaeliaceae. The new species E. quercina is described. Barrmaelia macrospora, B. moravica and B. rhamnicola are epitypified and E. perfidiosa is lecto- and epitypified. Published sequences of Anthostomella and several Anthostomella-like species from the genera Alloanthostomella, Anthostomelloides, Neoanthostomella, Pseudoanthostomella and Pyriformiascoma are evaluated, demonstrating the necessity of critical inspection of published sequence data before inclusion in phylogenies. Verified isolates of several species from these genera should be re-sequenced to affirm their phylogenetic affinities. In addition, the generic type of Anthostomella should be sequenced before additional generic re-arrangements are proposed.Electronic supplementary materialThe online version of this article (doi:10.1007/s11557-017-1329-6) contains supplementary material, which is available to authorized users.

Triblidiaceae is a family of uncommonly encountered, non-lichenized discomycetes. A recent classification circumscribed the family to include Triblidium (4 spp. and 1 subsp.), Huangshania (2 spp.) and Pseudographis (2 spp. and 1 var.). The apothecia of these fungi are persistent and drought-tolerant; they possess stromatic, highly melanized covering layers that open and close with fluctuations of humidity. Triblidialean fungi occur primarily on the bark of Quercus, Pinaceae and Ericaceae, presumably as saprobes. Though the type species of Huangshania is from China, these fungi are mostly known from collections originating from Western Hemisphere temperate and boreal forests. The higher-rank classification of triblidialean fungi has been in flux due in part to an overemphasis on ascospore morphology. Muriform ascospores are observed in species of Triblidium and in Pseudographiselatina. An intense, dark blue/purple ascospore wall reaction in iodine-based reagents is observed in species of Pseudographis. These morphologies have led, in part, to these genera being shuffled among unrelated taxa in Hysteriaceae (Dothideomycetes, Hysteriales) and Graphidaceae (Lecanoromycetes, Ostropales). Triblidiaceae has been placed within the monofamilial order Triblidiales (affinity Lecanoromycetes). Here, we demonstrate with a three-gene phylogenetic approach that triblidialean fungi are related to taxa in Rhytismatales (Leotiomycetes). We synonymize Triblidiales under Rhytismatales and emend Triblidiaceae to include Triblidium and Huangshania, with Pseudographis placed within Rhytismataceae. A history of Triblidiaceae is provided along with a description of the emended family. We discuss how the inclusion of triblidialean fungi in Rhytismatales brings some rarely observed or even unique ascospore morphologies to the order and to Leotiomycetes.

Cryptodicus muriformis and Schizoxylon gilenstamii (Stictidaceae, Ostropales, Lecanoromycetes, Ascomycota) are described as new to science from collections made in Europe (Sweden, Austria, Switzerland) and North America (Arizona), based on phylogenetic analyses of three loci. Both species show unique morphological characters that distinguish them from closely related species; Cryptodiscus muriformis, growing on decorticated or sometimes corticated branches of Picea abies and Pseudotsuga menziesii, that resembles C. foveolaris and C. tabularum in the yellowish-orange ascomatal disc, but is clearly distinguished by the muriform ascospores. Schizoxylon gilenstamii grows on dead stems of Globularia vulgaris and has a characteristic unique red-purple pigment in the epithecium and upper part of the excipulum that changes to bluish-green with KOH. We also report for the first time the anamorph of Stictis brunnescens.

Based on phylogenetic analyses of a multi-gene matrix of nuITS-LSU rDNA, RPB2 and TUB2 sequences and morphology, xylariaceous species with uni- to pauciperitheciate stromata and ascospores having a spirally coiling (helicoid) germ slit are revised and reclassified, including detailed descriptions and illustrations. The genus Helicogermslita is redefined and restricted to seven species with massive, erumpent, clypeus-like carbonaceous stromata, and Rosellinia somala is combined in Helicogermslita. Within the core Xylariaceae, the poorly known Leptomassaria simplex is shown to be closely related to Anthostoma insidiosum, for which the new genus Oligo­stoma is established, and Anthostoma rhenanum is demonstrated to be synonymous with O. insidiosum. The new genus Albicollum, characterised by immersed ascomata and a collar of white pseudostromatic tissues surrounding the ostioles, is established for Amphisphaeria canicollis, Anthostoma chionostomum, Sordaria (= Helicogermslita) fleischhakii and Anthostoma vincensii. Anthostoma ostropoides is synomymised with Albicollum canicolle, and Al. berberidicola, Al. longisporum and Al. novomexicanum are described as new species. Rosellinia (= Helico­germslita) gaudefroyi is transferred to the new genus Spiririma. Anthostoma amoenum and Euepixylon udum, both with a poroid germ locus, are shown to be only distantly related, and An. amoenum is reclassified within the asexual genus Digitodochium. Based on phylogeny, the genus Euepixylon is treated as a synonym of Nemania. A new species, Nemania ethancrensonii, which is closely related to the two formerly accepted Euepixylon species (E. sphaeriostomum, E. udum) but strongly deviates from the morphological concept of Euepixylon and Nemania, is described from the eastern USA. The genera Anthostomelloides, Clypeosphaeria, Digitodochium, Emarcaea, Induratia, Linosporopsis, Magnostiolata, Occultitheca and Spiririma are revealed to form a morphologically heterogeneous lineage in a basal position of Xylariaceae. Anthostoma vincensii, Quaternaria simplex and Rosellinia gaudefroyi are lectotypified, and Amphisphaeria canicollis, Anthostoma amoenum, An. rhenanum, An. vincensii, Quaternaria simplex, Rosellinia gaudefroyi and Valsa insidiosa are epitypified. Keys to uni- to pauciperitheciate xylariaceous genera with sigmoid to helicoid germ slits and to species of Albicollum are provided.