The spider fauna of the Aladjagiola wetland complex (Nestos Delta,north‐east Greece): a reflection of a unique zoogeographical transition zone in Europe

In order to increase our arachnological knowledge of Greece, and in particular north‐east Greece, an investigation of the arachnofauna of the Aladjagiola wetland complex was conducted from April to July 2008. The study area is part of the Nestos Delta in north‐east Greece, and comprises an area of approximately 20 km². Spiders were collected from 28 sites using pitfall traps. In all, 6694 specimens were sampled, including 206 species from 31 families. Altogether, 30 and 74 species were new to the districts of Greece and Macedonia, respectively. A number of faunistically interesting species were recorded during the study: Brachythele denieri (Simon, 1916), Camillina metellus (Roewer, 1928), Zelotes cingarus (O.P.‐Cambridge, 1874), Zodarion blagoevi Bosmans, 2009, Zodarion epirense Brignoli, 1984, Zodarion hauseri Brignoli, 1985, and Zodarion pirini Drensky, 1921, are Balkan endemics; Tegenaria angustipalpis Levy, 1996 and Titanoeca turkmenia Wunderlich, 1995 were newly discovered in Europe. Widespread elements represented the largest share of the species inventory, although chorological analysis indicated that the study area, as well as the whole north‐eastern part of Greece, is a reflection of a transition zone from the European fauna towards the Mediterranean and eastern (or Ponto–Anatolian) elements. Taken in combination, these affect the local fauna. The Balkan endemics, although small in number of species, further underline the unique identity of the area. Based on comparisons with data sets from the country's southernmost island, i.e. Crete, Greece can be regarded as a zoogeographical gradient. Hereby, Aladjagiola represents the northern edge, with European and Anatolian elements dominating the species inventory, and Crete represents the southern edge, with widespread but also endemic Mediterranean and eastern elements creating a more local and insular zoogeographical character. In conclusion, Greece cannot be viewed as a uniform zoogeographical unit, but rather as a mosaic of various regional zoogeographical patterns. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 217–233.