Species conservation profiles of endemic spiders (Araneae) from Madeira and Selvagens archipelagos, Portugal

The North Atlantic archipelagos of Madeira and Selvagens present a unique biological diversity including, presently, 56 endemic spider species. Several recent projects provide valuable information on their distribution across most islands and habitats. To date, the only endemic spider assessed according to the IUCN Red List criteria is Hogna ingens. The objective of this paper is to assess all remaining endemic species and advise on possible future conservation actions critical for the survival of endangered species.

Seven species were found to have a continuing decline in either range or population size. Their decline can be mostly attributed to habitat destruction or degradation, invasive plant species that reduce quality of habitat, forest fires at high mountain regions and possible competition for resources from invasive congeners. The tetragnathid M. barreti is considered as possibly extinct due to the suspected impact of a competing species. Although most endemic spiders from the Madeira and Selvagens archipelagos have relatively low extinction risk due to the good condition and protection of the laurisilva forests where many live, there are a number of species requiring urgent attention and protection measures. These include all cave and mountain-restricted species as well as those threatened by competing congeners or invasive plants. Extending current protected areas, restoring original habitats of threatened species and the control of invasive taxa should remain a priority for species survival.