Synopsis of the current knowledge of the purse-web spiders (Araneae: Mygalomorphae: Atypidae Thorell, 1870) in America

Abstract

This article deals with the biology as well as the diversity and distribution of the purse web spiders of the Atypidae Thorell, 1870 family in America. These mygalomorph spiders with three claws in their legs are characterized for having a hard plate in the anterior part of the dorsum of the opisthosoma, large and curved endites and very developed chelicerae sometimes larger in size than the carapace. This family includes 54 species grouped in the genera Atypus Latreille, 1804, Calommata Lucas, 1837 and Sphodros Walckenaer, 1835 of which the first and the last are represented in America by at least one species. Canada as well as Mexico have one species, S. niger (Hentz, 1842) and S. paisano Gertsch y Platnick, 1980 respectively; this family is more diverse in USA, where eight species are found, one Atypus and seven Sphodros, including those found in Canada and Mexico. The members of this family are associated with temperate forests, where they live inside in a sock-like nest made of silk, generally anchored to the ground and creeping onto the trunk of a tree or bushes and is camouflaged with the adhesion of substrate; this nest aids in the hunting technique which consists in waiting for an animal to walk on the nest to be later impaled, from inside the nest, by the long fangs of the spider. Unlike most other mygalomorph spiders, the Atypidae disperse by air by a mechanism called ballooning.