Ann. Zool. Fennici 48: 319–348 ISSN 0003-455X (print), ISSN 1797-2450 (online) Helsinki 30 December 2011 © Finnish Zoological and Botanical Publishing Board 2011 Polypore–beetle associations in Finland Dmitry S. Schigel Metapopulation Research Group, Department of Biosciences, Faculty of Biological and Environmental Sciences, P.O. Box 65, FI-00014 University of Helsinki, Finland (e-mail: dmitry.shchigel@helsinki.i) Received 21 Jan. 2011, revised version received 4 May 2011, accepted 10 Aug. 2011 Schigel, D. S. 2011: Polypore–beetle associations in Finland. — Ann. Zool. Fennici 48: 319–348. Seven old-growth, mostly spruce- and pine-dominated, protected forests rich in dead wood were inventoried for polypores and polypore-associated beetles in Finland in 2001–2007. A total of 198 polypore species (86% of the Finnish species list) were examined for associated Coleoptera. Of these, 116 species (59% of the studied species, or 50% of the Finnish polypore mycota) were found to host adults and/or larvae of 176 beetle species. Fifty-six polypore species were utilized by larvae of 21 beetle spe- cies. Many new fungus–beetle associations were discovered among 544 species pairs, including 421 polypore fruit body–adult Coleoptera species co-occurrences, and 123 fruit body–larva associations. Eighty-two species of fungi (41% of the studied species, or 36% of the Finnish polypores) were neither visited nor colonized by Coleoptera. Introduction During recent decades polypores have become one of the taxonomically best-studied groups of forest organisms in Finland (Niemelä 2005). Polypores are important indicator species as some of them survive only in old-growth forests with plenty of dead wood at different stages of decay (Kotiranta & Niemelä 1996, Niemelä et al. 2005, Halme et al. 2009), and many are red- listed (Rassi et al. 2010). Saalas (1917, 1923) and Palm (1951, 1959) were among the irst to document saproxy- lic (including fungivorous) Coleoptera in the Nordic region. Hundreds of fungus–beetle asso- ciations have been documented by Scheerpeltz and Höler (1948), Benick (1952), Nuss (1975) and Koch (1989a, b) for central Europe, by Alex- ander (2002) for the UK, and by Nikitsky et al. (1996) and Nikitsky and Schigel (2004) for the southern taiga of the Moscow region, Russia. Nikitsky (1993) reported the host fungi of Myc- etophagidae of Russia and adjacent countries, and Krasutskiy (2005) reported 208 fungicolous beetles and 89 species of their host fungi in the Urals and Transurals. Ehnström and Axels- son (2002) provided 18 main fungal hosts for 26 polyporicolous beetles with illustrations of their galleries. Selonen et al. (2005) reared 33 beetle species from 55 species of polypores, but reported beetles for only three hosts. At present, insect communities occurring in the fruit bodies of wood-decaying macrofungi are considered hotspots of insect diversity in boreal forests (Komonen 2003b). Only a few host fungi have been studied for associated beetles with sam- pling efforts suficient for statistical analyses of the data (for a detailed review of the literature, see Schigel 2009). Four polypore species, Fomes fomentarius, Fomitopsis pinicola, F. rosea, and Amylocystis lapponica have been particularly thoroughly studied (Thunes 1994, Nilsson 1997,