Open Access

Axel Ludwig Schönhofer, Thomas Holle

• N. bidentatum Roewer, 1914 was found at two places in Germany: first on the island “Harriersand” in the Weser river (Lower Saxony), second on the banks of the river Elbe in the Elbsandsteingebirge (Saxony). Adjacent to the latter locality an occurrence in the Czech Republic could be located close to the German/Czech border in the floodplain of the river Elbe as well. These records are the first for Germany and the Czech Republic. They enlarge the distribution area of N. bidentatum remarkably in both a northern and a western direction. The two populations show conspicuous differences in the form of the male cheliceral apophysis, which assigns them to the subspecies bidentatum Roewer, 1914 (in Lower Saxony) and sparsum Gruber & Martens, 1968 (in Saxony and the Czech Republik respectively). Differences, morphological characters and variability of the populations are illustrated. Relationships, abundance, ecology and provenance are discussed. N. dentigerum Canestrini, 1873 is recorded in Saxony for the first time. New records of N. triste C. L. Koch, 1835 and N. lugubre (Müller, 1776) are given.