Systematic revision of the Tubifera casparyi–T. dictyoderma complex: Resurrection of the genus Siphoptychium and introduction of the new genus Thecotubifera

ABSTRACT

The genus Siphoptychium is resurrected on the basis of comparative morphology and phylogeny of partial nuc 18S rDNA (18S) and translation elongation factor 1-alpha (EF1A) nucleotide sequences. The genus is characterized by the firm upper surface of the pseudoaethalium, accreted but easily separable sporothecae, a tubular or fibrous columella, and spores with a reticulate ornamentation consisting of 7–9 meshes across the diameter. In addition to the currently known single species S. casparyi (= Tubifera casparyi), two new members of Siphoptychium are described: S. violaceum from coniferous forests of Europe, east Asia, and southeast Asia, and S. reticulatum from temperate and subarctic regions of North America and alpine regions of Europe. A second genus, Thecotubifera, is described to accommodate Tubifera dictyoderma. The fruiting body of this species is transitional between a pseudoaethalium and a true aethalium. It is covered by a contiguous membranous cortex formed by the fused tips of the sporothecae, a feature typical for aethalia. However, the inner portions of sporothecae remain discernible, a feature more typical for pseudoaethalia. Columellae of Th. dictyoderma are formed by perforated plates, and the spores have a reticulate ornamentation consisting of 2–5 meshes across the diameter. For Th. dictyoderma, we could confirm records only for tropical regions and Japan, whereas all studied European specimens, including those mentioned in current monographs, represent species of Siphoptychium.

KEYWORDS:

• Capillitium
• columella
• cortex
• Lucisporomycetidae
• Myxomycetes
• phylogeny
• pseudoaethalium
• pseudocapillitium
• Reticulariaceae
• 4 new taxa
• 2 new typifications

ACKNOWLEDGMENTS

We are grateful to Marianne Meyer (France), David Mitchell (UK), Yury Ishchenko (Russian Federation), Bill Sheehan (United States), Edwin Johannesen (Norway), and Jiří Kubásek (Slovak Republic) for providing their collections for analysis. For assistance in sequencing of DNA from some specimens, we would like to thank Elisabeth Postel and Anja Klahr (Germany). For permission to collect myxomycetes we thank the authorities of the Bavarian Forest Natl. Park, and especially Dr. C. Bässler for help in the field work. We are grateful to the reviewers and the editor for important comments and suggestions.

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Funding

This research was partially supported by an award from the Fulbright Scholar Program to D.L. (grant 68130017) and a research stay of D.L. funded by the Deutsche Forschungsgemeinschaft under RTG 2010 (“RESPONSE”). Research of Y.N. was funded in part by the Komarov Botanical Institute RAS (AAAAA-19-119080990059-1) and the Russian Foundation of Basic Research (18-04-01232A). In addition, research carried out at the University of Arkansas was supported in part by the Slime Mold Project.