Ribosomal ITS diversity among the European species of the genus Hydnum (Hydnaceae)

Tine Grebenc,Hojka Kraigher,María P Martín

doi:10.3989/ajbm.2221

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).

Highlights

Members of the family Hydnaceae Chevallier (1826) are primarily identified by the presence of positive geotropic spines, ranging from small granular warts to clear individual spines (Ainsworth & al., 1973)
Huhtinen & Ruotsalainen (2006) examined the material from Finland and were able to separate all together three taxa within “H. rufescens” specimen: H. ellipsosporum, H. umbilicatum and H. rufescens s. str. with at least two separate populations in the latter species based on spore shape
The basidiome size, position of the stipe, distribution of the spines, and shape and colour of the basidiome were relatively reliable morphological criteria to distinguish these two morphological species without the need to employ molecular tools, yet our results indicate much higher diversity within these two species

Summary

Introduction

Members of the family Hydnaceae Chevallier (1826) are primarily identified by the presence of positive geotropic spines, ranging from small granular warts to clear individual spines (Ainsworth & al., 1973). Recent literature cites six valid genera in the family. Five of them were never included T. In any molecular analyses: Corallofungus Kobayasi, Dentinum Gray, Gloeomucro R.H. Petersen, Nigrohydnum Ryvarden, and Phaeoradulum Pat. 2001); while Hydnum as the type genus, was the only genus represented in phylogenetic studies. At higher taxonomic rank Hydnum was placed in Cantharellales first by Kreisel (1969) and later confirmed with molecular data by Pine & al. At higher taxonomic rank Hydnum was placed in Cantharellales first by Kreisel (1969) and later confirmed with molecular data by Pine & al. (1999) and subsequent papers

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