By Baral H.-O.
Vol. 7 (6) – 30 November 2015
Abstract: The taxonomic value of spore guttulation (lipid pattern inside of mature ascospores) studied with the light microscope from fresh but also dried collections is illustrated mainly for the two species of Hymenoscyphus extensively treated here. Also, the value of croziers at the ascus base is emphasized. The high intraspecific consistency of these characters permits rapid recognition of these species in the living state: H. menthae with multiguttulate ascospores and simple-septate asci, H. macroguttatus (= H. menthae s. auct.) with spores containing a few large oil drops and asci arising from croziers. Further valuable characteristics in the genus Hymenoscyphus concern the shape of ascospores (homo- versus heteropolar), the presence of polar setulae on them, and the vacuolar guttules in the living paraphyses. The neglect of spore guttulation due to the current dominance of herbarium studies, and also the neglect of croziers resulted in much confusion and name changes in this group of fungi. The traditional delimitation of taxa within Hymenoscyphus according to the substrate (lignicolous, herbicolous, pteridicolous) is questioned because quite a few species turned out to be highly plurivorous [...]