A new <e1>Chionosphaera</e1> species associated with conifer inhabiting bark beetles<fnr rid="fn1"><fn id="fn1">Part 191 in the series ‘Studies in Heterobasidiomycetes’ of the Botanical Institute, University of Tübingen.</fn>

An undescribed species of the heterobasidiomycetous genus <e1>Chionosphaera</e1> is carried by the bark beetles <e1>Dryocoetus autographus</e1>, <e1>Hylurgops palliatus</e1>, <e1>Ips acuminatus, Ips sexdentatus</e1>, <e1>Ips typographus</e1>, <e1>Orthotomicus laricis</e1>, <e1>Pityogenes chalcographus</e1>, <e1>Pityokteines spinidens</e1>, and <e1>Polygraphus poligraphus</e1> infesting conifers in Europe (<e1>Abies alba</e1>, <e1>Larix decidua</e1>, <e1>Picea abies</e1>, and <e1>Pinus sylvestris</e1>). <e1>Chionosphaera cuniculicola</e1> sp. nov. differs morphologically from <e1>C. apobasidialis</e1> in the more slender basidiospores. The segregation of the two species is supported by comparison of partial sequences of the large subunit of the ribosomal gene. Isotype material of <e1>Chionosphaera lichenicola</e1> was re-examined. In contrast to <e1>C. cuniculicola</e1> and <e1>C. apobasidialis</e1>, <e1>C. lichenicola</e1> exhibits clamps at the septa. <e1>Fibulostilbum phylacicola</e1> is considered as a clamp-bearing species of <e1>Chionosphaera</e1>.