FRAGMENTA FAUNISTICA 65 (1): 69–75, 2022 PL ISSN 0015-9301 © MUSEUM AND INSTITUTE OF ZOOLOGY PAS DOI 10.3161/00159301FF2022.65.1.069 Rediscovery of Isophya stysi (Čejchan, 1957) (Orthoptera: Tettigonioidea: Phaneropterinae) in south-eastern Poland Piotr GUZIK 1 and Wojciech GUZIK 2 1 Murowaniec 44, 38-455 Niżna Łąka, Poland; e-mail: piotrguzik85@gmail.com 2 Dębowa 22, 38-400 Krosno, Poland; e-mail: wfguzik@gmail.com Abstract: Isophya stysi (Čejchan, 1957), a flightless bush-cricket is one of only two Orthoptera species under strict legal protection in Poland. It reaches its northernmost range limit in northern Slovakia and south-eastern Poland. So far, it has been recorded from Poland only once, 50 years ago. We found numerous individuals of Isophya sp. in the Źródliska Jasiołki Nature Reserve (49°22'N, 21°54'E) already on 13 July 2011. However, only in 2019, we recognized that species as Isophya stysi. Later, we found it also at six other sites in SE Poland, five of which were located in the Beskid Niski Mountains and one near the town of Krosno. Key words: Stys’s plump bush-cricket, Beskid Niski mountains, distribution, insects, extensively used grasslands INTRODUCTION Isophya stysi (Čejchan, 1957) is endemic to the Carpathian Basin. The northern edge of its distribution reaches Slovakia (Krištín et al., 2019) and south-eastern Poland (Bazyluk 1971). It was also found in Ukraine, Romania, and Hungary (Heller et al. 2004, Krištín & Iorgu 2014). Its EOO (extent of occurrence) is estimated to be 130 000 km 2 (Chobanov et al. 2016). The main threats are agricultural activities and vegetation succession that cause degradation or loss of habitats (Chobanov et al. 2016). This species is of European importance (Annex II of the Habitats Directive; Council Directive 92/43/EEC 1992, Consolidated version January 1, 2007) and is strictly protected in Poland (Act on Protection of Nature of April 16, 2004). Isophya stysi is listed as Least Concern in the IUCN Red List of Threatened Species (Chobanov et al. 2016). Until now, Isophya stysi was recorded from Poland only once and only at one place in the Bieszczady mountains (SE Poland) during the survey that took place between 1964 and 1970 (Bazyluk 1971). The exact date of the observation has never been published. Later its occurrence at that place has not been confirmed despite searches by Theuerkauf et al. (2005) and Liana (2010). Since July 2011 we have known of one locality of Isophya sp. occurring in the Beskid Niski mountains (Źródliska Jasiołki Nature Reserve), and in 2019 we recognized that population as I. stysi based on acoustic analysis. The place is located about 70 km from the only known I. stysi record from Poland, however, the nearest discovered population of this species lies only ~3 km to the south, in Slovakia (Krištín 2022). This discovery suggested that the distribution of I. stysi at the northern edge of its range is insufficiently known in Poland, which led us to this survey. In 2019, 2020, and 2021, we found several additional sites in SE Poland. MATERIAL AND METHODS The research covered open and semi-open habitats located in the southern part of Podkarpackie (SE Poland). We visited them on warm, windless evenings and nights from June to September. All specimens were found by searching for exposed individuals and by acoustic detection of male calling song in places similar to habitats reported in the literature, namely