Neue Nachweise der Listspinne Dolomedes plantarius (Clerck, 1757) im Gebiet der Mittelelbe, Sachsen-Anhalt (Araneida: Pisauridae)

Abstract

Unruh, M.: New records of the fen raft spider Dolomedes plantarius (Clerck, 1757) in the Middle Elbe region, Saxony-Anhalt (Araneida: Pisauridae). – Hercynia N.F. 41 (2008): 143 –154.New records of Dolomedes plantarius, an Europe-wide endangered spider species, are reported from three stagnant water bodies in the Middle Elbe biosphere reserve and one site in the coal-mining landscape in the federal state of Saxony Anhalt. The three stagnant water bodies in the Elbe floodplains are situated in Special Areas of Conservation according to the European Union Habitats Directive. The records are discussed in respect to habitat preference, distribution and vulnerability of the species. The requirement of the species for stiff-leaved, emergent vegetation to support the nursery webs is confirmed, in the Elbe floodplain floating rosettes of water soldier Stratiotes aloides being the main habitat. The sparcity of former records is obviously due to inadequate methods of observation and collecting in limnic habitats. The current records nevertheless underline the high vulnerability of D. plantarius in a habitat, which itself is highly threatened. The sibling species Dolomedes fimbriatus, so far regarded as wide spread, has unto now not been found in the Elbe floodplains. Future attention to the spider fauna of water bodies with special regard to the two closely related Dolomedes-species is proposed. A special responsibility of the Middle Elbe biosphere reserve for the conservation of habitats of D. plantarius is stressed.