| Abstrakt: |
The new genus Luteodiscus is established to accommodate two species of bryoparasitic, helotialean discomycetes which are characterized by small, yellow, subsessile or short-stipitate, smooth to finely fimbriate apothecia that turn irreversibly bright rose-pink to wine-red in KOH. One of them, L. epibryus, was previously placed in Phialea and later Hymenoscyphus and has euamyloid ascus apical rings (IKI blue, type BB), comparatively long ascospores with a low lipid content, and apothecia which turn yellow-orange when dry. The much rarer L. hemiamyloideus is newly described and has hemiamyloid apical rings (IKI red, type RR), smaller ascospores with a higher lipid content, and smaller apothecia which turn blood-red when dry. Although previously known only from two collections on Hypnum, L. epibryus was found to have one of the most extensive and heterogeneous host ranges of all currently known bryophilous ascomycetes, comprising 14 genera in 6 orders of mosses and 14 genera in 2 orders of liverworts, with a maximum occurrence on Hypnum, whereas L. hemiamyloideus occurred on 6 genera in 2 orders of liverworts, with a preference for Nowellia, but never on mosses. Both species are necrotrophic parasites, forming apothecia within often conspicuous necrotic zones among healthy shoots of the host populations. The host bryophytes have been noted to grow on woody substrates (dead stumps, logs, branches, sometimes living trunks) or on mineral matter (soil and rock). Luteodiscus epibryus was mainly found in areas with acidic bedrock, whereas L. hemiamyloideus occurs at equal frequency over alkaline and acidic soil types. Both species were found in semi-shaded to shaded forests but also in open wood- and shrublands, composed of various angiosperms and/or gymnosperms. While L. epibryus is here reported from Europe, Macaronesia, and North America, L. hemiamyloideus has so far solely been recorded in Europe. Although L. epibryus was found to be frequent in many regions, with so far 114 collections made mainly in the period of 1989–2024, only two collections with published descriptions came to our notice: the holotype from Czechia collected in 1906 and a much younger undated collection from dépt. Orne, France. In comparison, L. hemiamyloideus was recorded only 15 times during 2011–2024. Sequences of rDNA obtained from six collections of L. epibryus and two of L. hemiamyloideus revealed a strong difference between the two species, ranging at p-distances of 8.4–8.9% in the ITS region and 2.7–2.9% in the LSU D1–D2 domain. Two genotypes with a 0.8% p-distance in ITS and 0.2% in LSU were observed within L. epibryus, but without any expression in the phenotype. Combined phylogenetic analysis of ITS + LSU D1–D4 suggests that Luteodiscus belongs in Hyphodiscaceae. [ABSTRACT FROM AUTHOR] |
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