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.

A list of all generic names that have been connected with the Orbiliomycetes is provided. Recommendations are made as to which names should be used in accordance with the rules and the different generic concepts. There is a mismatch in the current generic concepts within Orbiliomycetes regarding the two morphs: a narrow concept is used for the asexual morphs, but a broad concept relies on the sexual morphs. As a consequence, many more generic names have been established for the asexual morphs. A number of previous generic concepts are artificial, since they were based on single characters without molecular support. In order to provide solutions for this mismatch, we present three different generic concepts within the Orbiliomycetes. A broad concept recognizes a large genus Orbilia, with which most of the listed names fall into synonymy, but could be maintained as infrageneric names. Due to the lack of data proving phylogenetic relationships, this broad concept, at present, is the most practicable and recommended one. A moderate concept subdivides Orbilia into several genera, with all nematodetrapping fungi merged in Arthrobotrys. A narrow generic concept accepts genera based on differences in trapping organs, but also subdivides the remaining groups of Orbilia into Section Editor: Roland KirschnerThe last eight authors are listed alphabetically, contributing by phylogenetic results or in advisory capacity.This article is part of the "Special Issue on ascomycete systematics in honour of Richard P. Korf who died in August 2016".Electronic supplementary material The online version of this article (doi:10.1007/s11557-017-1300-6) contains supplementary material, which is available to authorized users.

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Glyphium encompasses species with erect, carbonaceous ligulate to dolabrate ascomata that are strongly laterally compressed and dehisce along a longitudinal slit. The five currently recognized members of the genus are separated primarily by whether the ascospores disassociate into part-spores within the ascus. Glyphium has traditionally been placed in Mytilinidiaceae (Mytilinidiales, Pleosporomycetidae, Dothideomycetes). The present study, based on freshly collected material of G. elatum and G. grisonense, was initiated to determine the phylogenetic placement of Glyphium. Phylogenies inferred from the analysis of sequences of six gene regions (nuLSU, nuSSU, mtSSU, TEF1, RPB1, RPB2) derived from six accessions indicate that Glyphium belongs to Patellariales (Pleosporomycetidae, Dothideomycetes) . Our phylogenies also support the phylogenetic relationship of Patellaria and Hysteropatella within this order. The nomenclatural history of Glyphium is summarized and a key to species is provided.

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