Chrząszcze wodne (Coleoptera: Adephaga, Hydrophiloidea, Byrrhoidea) Gór Świętokrzyskich

The water beetles (Coleoptera: Adephaga, Hydrophiloidea, Byrrhoidea) of the Świętokrzyskie Mountains. Based on our own, original long-term fieldwork carried out between 1979 and 2021, as well as analyses of the collections acquired during fieldwork performed by researchers from the University of Łódź in 1980-85, we have recorded the presence of 156 water beetle species from 12 families in the Świętokrzyskie Mountains, 51 of which are new to this region. We have placed special emphasis on the Świętokrzyski National Park, the water beetle fauna of which has to date been poorly researched, where we found 121 species of these beetles from 12 families, including 102 new to the Park. The 51 species new to the Świętokrzyskie Mountains and the 102 new to the Świętokrzyski National Park, that is, 30.18 and 82.93%, respectively, of the numbers of species found hitherto, significantly enhance our knowledge of water beetles in this region. But the real and lasting value of this work is the fact that it is based on a vast array of voucher specimens, covering a period of more than 40 years. 
The paper begins with a brief history of the study of water beetles in the Świętokrzyskie Mountains. It then discusses the aim of the work, the nomenclature and systematics, and the methodology. The next section characterizes the study area, i.e. its position and boundaries, geomorphology, geological structure and orogenesis, climate, vegetation, and finally, the most common types of water bodies and watercourses that could have a bearing on the water beetle fauna. This section concludes with the criteria we applied for classifying localities to the Świętokrzyski National Park. It also contains maps and some of the photographic material illustrating the various localities, which are listed in the next section, the List of Localities. The Results section contains a table of the species recorded; it specifies those that are new to the Świętokrzyskie Mountains and the Świętokrzyski National Park, and also the type of distribution and the ecological requirements of each species. In the Discussion and Conclusions, we analyse the richness of the study area’s water beetle fauna based on our own fieldwork and the literature data by comparing it with other mountain regions of Poland, current knowledge of the various water beetle families, their types of distribution, zoogeographical elements and ecological requirements. This section ends with a discussion of the most interesting species recorded. Importantly, eight of the species found in the Świętokrzyskie Mountains are on the Polish Red List of Endangered Species (Pawłowski et al. 2002): one is Critically Endangered (CR) – Spercheus emarginatus (Schaller), two are Endangered (EN) – Hydroporus longicornis Sharp and Haliplus varius Nicolai, three are Vulnerable (VU) – Hydroporus brevis F. Sahlberg, Ilybius wasastjernae (C.R. Sahlberg) and Hydrophilus aterrimus J.F. et von Eschscholtz, one is of Least Concern – Brychius elevatus (Panzer) (LC), and one is probably endangered (data deficient DD) – Pomatinus substriatus (Ph. Müller).
The fact that we found extremely rare species, not recorded in Poland for more than 100 years, as well as endangered or relict species like Hydroporus brevis and Ilybius wasastjernae with highly specific habitat demands, justifies our specifying hitherto unprotected areas, especially those immediately contiguous with the Świętokrzyski National Park, where conservation measures are urgently needed. 
In summary, our research has added 109 species to the list of water beetles recorded in the Świętokrzyski National Park, an increase of a little over 5% compared with the number given in Buchholz et al. (2021).