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.

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All groups of macrofungi were recorded on 32 large fallen trunks of pedunculate oak (Quercus robur) in various decay stages in the strictly protected zone of Białowieża National Park, Poland. The total number of species was 187 with 4-38 species per trunk. The mycobiota of individual trunks was unique, consisting of a variable set of several frequent species, a high number of infrequent to rare ones, and a considerable proportion of mycorrhizal fungi and species preferring conifer wood. Relations between trunk parameters, surrounding vegetation and fungal occurrences were analysed using multivariate statistical methods. The number of fungal species per trunk was significantly correlated with trunk orientation, which reflects the heat load via forest canopy gap, trunk size parameters, percentage of bark cover and contact with the soil. The species-richest trunks were those covered by bark, of larger volume (thick, long), not exposed to heat from afternoon sun, but, simultaneously, with lower canopy cover. Orientation (azimuth) of the fallen trunks proved to be significant also for the fungal species composition of a particular trunk, which also reflected trunk size characteristics, its moss/bark cover and contact with the soil. Presence of some dominants (Ganoderma applanatum, Mycena inclinata, Kretzschmaria deusta, Xylobolus frustulatus) had a significant effect on fungal community composition. Some herbs requiring nutrient-rich soils occurred in the vicinity of trunks with a larger contact area with the soil and in later stages of decay. The process of oak trunk decay in relation to fungi and surrounding vegetation is outlined.

Boubínský prales virgin forest is the best-preserved montane Picea-Fagus-Abies forest in the Czech Republic. Its core area (46.67 ha), grown with original montane forest never cut nor managed by foresters, has been protected since 1858. It represents the centre of the present-day nature reserve (685.87 ha). A detailed inventory of its fungal diversity was carried out in 2013-2014. Ten segments differing in habitat and naturalness were studied (235 ha). The total number of species was 659, with the centre of diversity in the core area (503 species) followed by the neighbouring segments grown by natural forests minimally influenced by man. When literature and herbarium data are added, the total diversity reaches a total of 792 taxa. The locality represents a unique refugium for some borealmontane fungi (e.g. Amylocystis lapponica, Laurilia sulcata, Pholiota subochracea), a high number of rare species preferring old-growth forests (Antrodia crassa, A. sitchensis, Baeospora myriadophylla, Chrysomphalina chrysophylla, Fomitopsis rosea, Ionomidotis irregularis, Junghuhnia collabens, Skeletocutis odora, S. stellae, Tatraea dumbirensis), wood-inhabiting and mycorrhizal fungi confined to Abies (Panellus violaceofulvus, Phellinus pouzarii, Pseudoplectania melaena, Lactarius albocarneus), and a high number of indicators of well-preserved Fagus forests (e.g. Climacodon septentrionalis, Flammulaster limulatus, Pholiota squarrosoides). Several very rare fungi are present, e.g. Chromosera cyanophylla, Cystoderma subvinaceum and Pseudorhizina sphaerospora. The value of the local mycobiota is further emphasised by the high number of protected and Red List species. Comparison with other Central European old-growth forests has confirmed that Boubínský prales is a mycological hotspot of European importance.