The latitudinal diversity gradient predicts higher species richness at lower latitudes. Here, we utilize the data from a long-term monitoring with malaise traps to analyse if spider communities in Sweden are affected by geographic gradients and if these effects hold independent of forest type. The species richness and the effective number of species in spider communities were not significantly related to the latitudinal gradient. The effective number of species and the taxonomic distinctness of spider communities were related to longitude, with a higher number, but fewer related species in western parts of Sweden. The species and family composition were significantly related to latitude independent of forest type, with a dominance of Linyphiidae individuals and species in the north. Our study demonstrates the suitability of malaise trap sampling to contribute to a better understanding of local spider communities, as several rare and locally new species were recorded in this study.
The rare spider species Agroeca dentigera Kulczyński, 1913 (Liocranidae) and Entelecara omissa O. P.-Cambridge,1902 (Linyphiidae), have been found in a small coastal freshwater fen in Lomma (55°42'N 13°4'E),north of Malmö in Scania in southernmost Sweden. A. dentigera was also found on a salt water meadow southof Malmö. Both species have been found only in a few wet localities in Europe. Entelecara depilata Tullgren, 1955,is a junior synonym of Entelecara omissa O. P.-Cambridge, 1902, new synonymy.
The spider fauna of the Skäralid Gorge, in southernmost Sweden, was investigated in 1994 and 1995. Nine stations in partially different biotopes were sampled with pitfall traps. Trees, bushes and cliffs were also investigated by various methods. The slopes and screes are sparsely populated. However, in most biotopes diversity is rather high. On the northern slopes and in the bottom of the gorge some cold-adapted northern species are found. In the rather dark, shaded and, moist bottom of the gorge live typical forest species, including some rare spiders such as Robertus neglectus, Lepthyphantes angulatus, Diplocentria bidentata and Coelotes atropos. The sunny slopes have the most interesting spider fauna, with rich populations of Atypus affinis, Pardosa alacris, Liocranum rupicola, Zelotes subterraneus, Scotina celans, and Sitticus pubescens. Three species of Pardosa lugubris s.l. live in Skäralid: P. lugubris s.s. in the shaded, forested parts, P. saltans on partially shaded slopes and P. alacris in sunnier and stonier parts of the southern slopes. On trees and bushes on the slopes some thermophilous species can be found, such as Araniella inconspicua.