Hydnum

Abstract: Hydnum is a fungal genus proposed by Linnaeus in the early time of modern taxonomy. It contains several ectomycorrhizal species which are commonly consumed worldwide. However, Hydnum is one of the most understudied fungal genera, especially from a molecular phylogenetic view. In this study, we extensively gathered specimens of Hydnum from Asia, Europe, America and Australasia, and analyzed them by using sequences of four gene fragments (ITS, nrLSU, tef1α and rpb1). Our phylogenetic analyses recognized at least 31 phylogenetic species within Hydnum, 15 of which were reported for the first time. Most Australasian species were recognized as strongly divergent old relics, but recent migration between Australasia and the Northern Hemisphere was also detected. Within the Northern Hemisphere, frequent historical biota exchanges between the Old World and the New World via both the North Atlantic Land Bridge and the Bering Land Bridge could be elucidated. Our study also revealed that most Hydnum species found in subalpine areas of the Hengduan Mountains in southwestern China occur in northeastern/northern China and Europe, indicating that the composition of the mycobiota in the Hengduan Mountains reigion is more complicated than what we have known before.

Abstract: We have carried out a morphological and molecular study of Mycoacia nothofagi and Steccherinum lusitanicum, two rare irpicoid species collected in Spain. From Steccherinum lusitanicum, only the type of the species, collected in Portugal, was known to date. This has been compared with type material of Hydnum setulosum (≡Hyphodontia setulosa) collected in the USA, confirming that both species are synonymous. We contribute with microphotographs of the most representative characters of the specimens. The molecular data based on ITS and partial 28S rRNA gene sequences show that both taxa should be accommodated within genus Phlebia. Our data suggest a close relationship between S. lusitanicum and the core of Phlebia sensu stricto (including the type species P. radiata), whereas M. nothofagi is apparently more closely related with another group of species that would include M. aurea, P. subserialis and P. livida, among others. The molecular phylogenetic analysis confirms that the genera Mycoacia and Mycoaciella, as well as Merulius, should be considered as synonyms of Phlebia.

Abstract: Grebenc, T., Martin, M.P. & Kraigher, H. 2009. Ribosomal ITS diversity in the European species of the genus Hydnum (Hydnaceae). Anales Jard. Bot. Madrid 66S1: 121-132. Several morphological species of the genus Hydnum L. are known to occur in Europe, but little molecular evidence exists to confirm the exact number and delimitation of the species. The present study seeks to investigate the genus Hydnum through sequence analysis of the nuclear ribosomal ITS regions and through morphological studies. The DNA sequences phylogenetic analysis revealed high diversity among the ITS region sequences in H. repandum (two clades) and H. rufescens (six clades) while the specimens of H. albidum, H. umbilicatum and H. ellipsosporum formed one and clearly separated clade per morphological species. Phylogenetic distances among the recognised species and the obtained morphologically unsupported clades are comparable and support the idea of several new, yet undescribed species. The intraspecific variability in the sequence data among phylogenetic species is generally low. Detailed morphological analysis of putative informative morphological characteristics could not support any of the observed non-monophyletic DNA-sequences clades within H. repandum or H. rufescens, and the proper use of names is not yet clear. Similar intraspecific variation has also been observed in many other ectomycorrhizal genera and could be explained by intensive speciation within variable groups under the influence of various factors (niche effect, ectomycorrhizal partner selection).