Nehalennia speciosa (Charpentier, 1840) in Europe: a case of a vanishing relict (Zygoptera: Coenagrionidae)

Based on all available data, the former and present distribution in Europe is presented and critically analysed. The sp. is extinct or has only survived at single or small clustered and isolated localities in many parts of the western borderlands of its former Eurasian area that extended from Belgium to Japan. It is continuously declining, especially W and S of the line running through the Baltic States, N and E Poland and S Belarus. The attached basic data from Asia reveal incomplete knowledge, but probably indicate a better situation in the eastern part of the range. The main aspects of the ecology and biology are outlined and discussed. Special attention is paid to the elements helpful in understanding the deep regress of the sp., i.e. to its habitat on a macro- and microscale as well as to its life-strategy. The high level of stenotopy and the highly specialized habitat-related behaviour, resulting in successful use of a narrow niche, are emphasized. These aspects make the sp. vulnerable in the face of high anthropogenic pressure in Europe. Limited dispersal abilities augment the danger of local extinction. The main threats are presented and some essential conservation measures are proposed.