Variability of Hydnum rufescens in Finland: three taxa hidden under one name – and appearance

Authors: Huhtinen, Seppo & Ruotsalainen, Juhani
Journal: Karstenia, Volume 46 (2006), Issue 1, pages 17-24.
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Key words: Basidiomycota, Hydnum, taxonomy

Abstract: Recent observations revealed large variability in spores between materials collected as Hydnum rufescens Fr. New collections and herbarium specimens indicated that Finnish material can be divided into three entities based on spore characters. One of these, with ellipsoidal spores, was described as new by other workers. This species, Hydnum ellipsosporum Ostrow & Beenken, is not rare in Finland. In Finnish populations of H. rufescens s.str. spores are typically globose. Populations with intermixed broadly elliptical spores are more rare. Spore size inH. rufescens is clearly smaller than in H. umbilicatum Peck, in which spores are uniformly globose. A study of the holotype showed spore characters identical to the Finnish material. Hence, H. umbilicatum is claimed to be part of typical European mycoflora; it seems to be fairly common in Finland. Observations made so far indicate that macromorphology and colours may be too variable for a definitive identification in the field. Some possibly helpful, mainly hymenial, characters are discussed. Two collections of H. rufescens are reported from Canada. Colour photographs of all the discussed taxa are provided.