The occurrence of Triaenodes unanimis McLachlan, 1877 (Insecta: Trichoptera) and other rare species of caddisflies in the Powidz Landscape Park (Poland)

The paper presents the results of studies from 2008, 2009, 2018 and 2021 on the trichopteran fauna of Lake Powidzkie Małe as well as the peatlands of Powidz Landscape Park. The total of 25,091 caddisfly specimens of 47 species were collected. Among them were three species from the Red List of Threatened Animals in Poland – Triaenodes unanimis McLachlan, 1877, Ceraclea nigronervosa (Retzius, 1783) and Oecetis notata (Rambur, 1842) – and four species rare in the fens of Poland – Holocentropus stagnalis (Albarda, 1874) and Cyrnus insolutus McLachlan, 1878. T. unanimis is rare worldwide, including Poland. This is the fourth known site of T. unanimis in Poland and at the same time the most westerly Polish site of this species. The typical habitat of T. unanimis is defined on the basis of available habitat data and my own results.