Observations of overwintering nymphalid butterflies in underground shelters in SW and W Bohemia (Czech Republic) (Lepidoptera: Nymphalidae: Nymphalini) LIBOR DVOřÁK Šumava National Park Administration, Dept. of Science and Research, Sušická 399, CZ-34192 Kašperské Hory, Czech Republic. libor.dvorak@npsumava.cz, lib.dvorak@seznam.cz JOSEPH BELICEK 15004-96 Avenue, Edmonton, Alberta, Canada T5P 4M7. polygonia@shaw.ca ZDENěK FRIC Biology Centre of the Academy of Sciences of the Czech Republic, Branišovská 31, CZ-37005 České Budějovice, Czech Republic. fric@entu.cas.cz Abstract. The results from ten years of surveys and observations of overwintering nymphalid butterflies in various types of underground shelters in SW-W Bohemia, Czech Republic are presented. During these surveys, three species of nymphalid butterflies were encountered; the most commonly observed species was Inachis io (Linneaus), followed by Aglais urticae (Linneaus). Nymphalis polychloros (Linneaus) was encountered in the ten year period only twice. The typical overwintering sites for Inachis io were the ceilings of unheated cellars of buildings, and the entrances of mining tunnels/galleries or natural caves. A special category of underground shelters in the study area was abandoned World War 2 military bunkers. Inachis io frequently hibernates in aggregations of several individuals and Aglais urticae does so less often. The lowest ambient air temperature measured in these underground shelters was –1.1° C. It is believed that these observations represent the longest continuous record of hibernating nymphalid butterflies in underground (or other) shelters in Czech Republic. Key words: phenology, ecology, overwintering sites, winter diapause, hibernation, Anglewing butterflies, butterfly conservation, natural resource protection INTRODUCTION The Anglewing butterflies are a small group of nymphaline butterflies inhabiting the Northern Hemisphere (ca. 35 sp.). It is generally agreed that this group is a natural monophyletic clade, based on several synapomorphic characters including special adaptations that enable the adults to survive the winter in hibernation (hibernal diapause) (see Scott, 1979). Recent phylogenetic studies (Nylin et al., 2001; Wahlberg & Nylin, 2003; Wahlberg et al., 2005) confirmed the monophyletic relationship for the Anglewing butterflies as a group. For the purposes of this paper we recognize the genera Aglais, Inachis, Nymphalis, and Polygonia. However, it may turn out that there are only two genera: Aglais and Nymphalis comprise the Anglewing butterflies. If that is the Received: 10 November 2006 Accepted: 5 May 2008 case, then Inachis would become a junior subjective synonym of Aglais and likewise Polygonia becomes a junior subjective synonym of Nymphalis. For the purposes of this paper we recognize the genera Aglais, Inachis, Kaniska, Nymphalis, Polygonia and Roddia. The genus Kaniska is not represented in Europe, and the Euro-Asian Roddia l-album does not occur recently in Bohemia. There are a few more or less anecdotal notes regarding overwintering nymphalines from Bulgaria (Beshkov & Petrov, 1996), former Czechoslovakia (cf. Košel, 1984; Dvořák, 2000, 2002), France (Sarlet, 1982), Germany (Bronner, 1987; Herhaus & Karthaus, 1996), Poland (Kowalski, 1955), Spain (Escola, 1982) and others. This paper reports observations of primarily Inachis io (L.) and Aglais urticae (L.). With the onset of fall, typically at the end of August, these butterflies begin to search for suitable overwintering shelters. Depending on the species, the selected sites vary. The most frequently observed 41: 45-52,2002 (2009) Journal of Research on the Lepidoptera