The comprehensive checklist of myxomycetes of Ukraine, based on extended occurrence and reference datasets.

Background: A significant body of valuable data about the myxomycetes of Ukraine lies in a "grey zone". This encompasses undigitised historical books and articles published in languages such as Polish, French or German, as well as proceedings from local conferences, articles featured in local scientific journals and annual reports submitted to public authorities by employees of protected areas, published in Ukrainian or Russian. Yet, due to their exclusive existence in print and often the Cyrillic alphabet, these publications remain neither findable nor accessible to a wider audience. New information: The datasets presented here aim to summarise over 150 years of myxomycetes research in Ukraine. The majority of the data has been extracted from published literature sources spanning the years 1842 to 2023, with a minor supplement from unpublished herbarium specimens. The datasets include 5036 georeferenced occurrences, 339 taxa and 91 literature sources. Seventy-one of the used literature sources, mostly published before 2010, were uploaded to Zenodo and are available in open access.

Tasmaniomyxa umbilicata, a new genus and new species of myxomycete from Tasmania.

A new genus and species of myxomycete, Tasmaniomyxa umbilicata, is described based on numerous observations in Tasmania and additional records from southeastern Australia and New Zealand. The new taxon is characterized by an unusual combination of characters from two families: Lamprodermataceae and Didymiaceae. With Lamprodermataceae the species shares limeless sporocarps, a shining membranous peridium, an epihypothallic stalk, and a cylindrical columella. Like Didymiaceae, it has a soft, flaccid, sparsely branched capillitium, with rough tubular threads that contain fusiform nodes and are firmly connected to the peridium. Other characters of T. umbilicata that also occur in many Didymiaceae are the peridium dehiscing into petaloid lobes, the yellow, motile plasmodium, and the spores ornamented with larger, grouped and smaller, scattered warts. The transitional position of the new taxon is reflected by a three-gene phylogeny, which places T. umbilicata at the base of the branch of all lime-containing Physarales, thus justifying its description as a monotypic genus.