Faunistiek en dynamiek in de spinnenwereld 2020

Apparent changes in the Dutch spider fauna are described. General trends are speculated about. Two new species of Salticidae (Macaroeris nidicolens (Walckenaer, 1802) and Saitis barbipes (Simon, 1868)) appear to have settled in the Netherlands over the last years. It is not always clear for specimens of European species detected for the first time in the Netherlands whether they were recently imported or were already established. A female of Olios argelasius found in the Netherlands was kept alive long enough to observe the production of an egg cocoon and pulli showing the possibility of starting a population through import of a female which had already mated. It is impossible to monitor all the spider species in the Netherlands. However, for one species in one area this is done on a yearly basis: Dolomedes plantarius (Clerck, 1757) of which the webs and egg cocoons are counted traditionally: the population is sound and safe.