This publication is primarily an identification key to the adults and nymphs of the stoneflies (Plecoptera) of the Netherlands. Adults and nymphs are treated in separate keys. Keys to the different genera are given, followed by keys to the species for genera containing more than two species. All Dutch species are included, as well as some potential new species from adjacent regions. In the second part of the book, species descriptions are given with information on recognition, distribution, ecology and biology.
According to current knowledge, the Dutch Plecoptera fauna consists of 27 species, 17 of which have not been recorded for at least 50 years. This means that stoneflies are among the most endangered animal groups in the Netherlands. A complete list of the Dutch fauna, as well as an indication of the current occurrence of each species, is presented in Appendix 1. This appendix also lists the species known from adjacent regions. A systematic checklist of all the species treated in this publication can be found on page 28. Compared to the last major revision of the Dutch stoneflies (Claessens 1981), two species (Siphonoperla burmeisteri and Protonemura nitida) have been removed from the list, while one species (Protonemura risi) has been added. The specimens which were considered Siphonoperla burmeisteri are S. torrentium (as already noted by Zwick (1971)). Reexamination of the Protonemura-material revealed that the only Dutch specimen of Protonemura nitida belongs to P. risi. A population of P. risi was found in 2005 (Van den Hoek 2006).
Since 1981, only minor changes in the Dutch Plecoptera fauna have occurred. The most remarkable record is that of several specimens of Perlodes microcephalus (the last species of the Systellognatha still known from the Netherlands) in 1995 (and subsequent years) in the Roer, a lowland river in the south of the Netherlands, which is recovering from pollution. On the other hand, the species disappeared from the Geul, another river in the extreme south of the Netherlands from where it was known for decades. Periods of drought seemed to have affected local populations of especially Nemoura avicularis. Although many streams recovered (more or less) from pollution, no other recolonisations by stoneflies have been reported, so far.
Summary in Dutch:
Steenvliegen zijn ranke, langvleugelige insecten, waarvan de larven in schone, snelstromende wateren leven. Vroeger kwamen in de Nederlandse beken en rivieren 27 soorten voor, maar door waterverontreiniging verdwenen maar liefst 17 soorten. Daarmee kunnen steenvliegen de meest bedreigde diergroep in Nederland genoemd worden.
Wie in het vroege voorjaar een bezoek brengt aan een kabbelende beek in Zuid- of Oost-Nederland, heeft echter nog altijd een grote kans om steenvliegen te vinden. Door de betere waterkwaliteit is het zelfs mogelijk dat sommige verdwenen steenvliegen zich opnieuw zullen vestigen.
In dit boekje wordt voor her eerst alle informatie over Nederlandse steenvliegen gebundeld. De sleutel, met ruim 300 illustraties, biedt de mogelijkheid om zowel de larven als de volwassen dieren op naam te brengen.