Dehydration and self-cell cleaning by a single cell drives the formation of fruiting body of Lamproderma columbinum (Myxomycetes)

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.

Revisiting the morphology of Lamproderma reveals incongruities among the taxonomic characteristics of higher classifications of Myxomycetes

Despite various attempts during the last few decades to establish a natural system for the Myxomycetes, researchers have not yet reached a consensus. One of the most drastic recent proposals is the movement of the genus Lamproderma, an almost a trans-subclass transfer. The traditional subclasses are not supported by current molecular phylogenies, and various higher classifications have been proposed during the last decade. However, the taxonomic characteristics on which the traditional higher classifications were based have not been reinvestigated. In the present study, the key species involved in this transfer, Lamproderma columbinum (the type species of the genus Lamproderma), was assessed using correlational morphological analysis of stereo, light, and electron microscopic images. Correlational analysis of the plasmodium, fruiting body formation, and the mature fruiting bodies revealed that several concepts of taxonomic characteristics that have been used to distinguish higher classifications are questionable. The results of this study indicate that caution is required when interpreting the evolution of morphological traits in Myxomycetes, as the current concepts are vague. The definitions of the taxonomic characteristics need a detailed research, and attention should be paid to the lifecycle timing of observations, before discussing a natural system for Myxomycetes.