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The spider family Cybaeidae includes 178 spp (Platnick 2013), the great majority of them in the genus Cybaeus, with around 80 species found in North America north of Mexico. The family has a mainly Holarctic distribution, with most species occurring in Japan and western North America. In North America, one species of Cybaeota and three of Cybaeus are found in forested uplands of the east; all the other North American cybaeids are found west of the continental divide from far out on the Aleutian Islands (two species) to the Mexico/United States border. Cybaeus is a Holarctic (=Palearctic + Nearctic) genus, but the other genera found in North America are apparently Nearctic endemics. (Bennett 2005).
Cybaeids typically inhabit the leaf litter on the forest floor and are among the most commonly encountered spiders in the forests of western North America, but they can be found in habitats ranging from coastal and riparian beach litter to alpine meadows. One species is known to be found in moss on deciduous tree trunks in coniferous forests in western North America, a number of species live underground, and the European Argyroneta aquatica is the world's only known entirely aquatic spider. Most cybaeids build small webs that are best described as a type of funnelweb and which probably function as retreats. The webbing is usually hidden under a rock or log with just a small amount, or even just a few signal lines, extending into the open. (Bennett 2005 and references therein; Bradley 2013)
Like most spiders, cybaeids have eight eyes. Cybaeids typically have conical spinnerets (with the anterior pair being somewhat longer than the posterior pair), spiny legs, and a hairless and shiny carapace (Bradley 2013).
Bennett (2005 and references therein) reviewed the limited published and unpublished information available about the natural history of cybaeids. Bennett (2005) also reviewed the complex taxonomic history of this family, the delineation of which remains difficult. Copley et al. (2009) reviewed the systematics of the genus Cybaeus.