Interest on Madeira spider fauna started almost two centuries ago (Blackwall 1859, Blackwall 1862, Bösenberg 1895, Bristowe 1925, Denis 1962, Denis 1963, Denis 1964, Johnson 1863, Kulczynski 1899, Kulczynski 1905, Lowe 1832, Schenkel 1938, Schmitz 1895, Warburton 1892) and has continued until recently, with the description of several new species (Wunderlich 1987, Wunderlich 1992, Wunderlich 1995). Despite the major relevance for the knowledge of Madeiran spider biodiversity, these taxonomic studies are based on traditional ad-hoc manner, without a standardized methodology, which renders them inappropriated to explore species distribution patterns. In other words, although the ad-hoc approach may be useful in targeting specific localities or ecological niches by experienced collectors (Cardoso et al. 2009), it does not capture the real distribution of species. The lack of knowledge on species distribution is now referred to as the Wallacean shortfall (Lomolino 2004; see Cardoso et al. 2011), and the main objective of this contribution is to help to overcome this shortfall for Madeiran spiders associated with the native laurel forest – Laurisilva.

Laurisilva is a relict evergreen forest that covered part of the Mediterranean Basin during the Tertiary, being restricted nowadays to a few locations in the Macaronesian archipelagoes of the Azores, Madeira and Canary Islands, and in some secluded sites of North Africa (Neves et al. 1996). In the archipelago of Madeira, Laurisilva is restricted to the main island (Madeira), covering about 16000 ha and harbouring a large number of endemic fungi, plants and animals (Uva 2008; Borges et al. 2008). Taking in consideration the high natural value of this forest type, now internationally recognized (IUCN 1999, Myers et al. 2000), local entities created the Natural Park of Madeira with the aim of valuing, studying and protecting this unique ecosystem.

The latest spider checklist (Cardoso and Crespo 2008) reports the occurrence of 164 species for Madeira island. Among these species, 40 are considered single-island endemics (SIE) and some belong to genera that radiated in Madeira archipelago (e.g. Dysdera Latreille, 1804, Hogna Simon, 1885, Pholcus Walckenaer, 1805). Approximatelly 63% of the SIEs were collected exclusively from Laurisilva sites, strongly suggesting an intimate association between these species and this type of habitat. Although the Natural Park of Madeira has developed major efforts to protect and restore Laurisilva patches from human activities and invasive species, conservation measures specifically targeting endemic terrestrial arthropod fauna are yet to be put forward. Preliminary conservation priorities for the endemic invertebrate fauna have already been identified using taxonomically unbiased criteria (Martín et al. 2010, Martín et al. 2008), but there is still a lack of baseline information for most species. The collection of species distribution and abundance data using standardized sampling is paramount to assess species conservation status. The aim of our study is therefore to provide information on the distribution of spiders endemic to the Laurisilva of Madeira island based on a large-scale assessment using standardized sampling.