''Callobius severus'' is a species of spider found in parts of the United States and Canada. Individuals reach roughly 19 mm (3/4") in size, with males typically appearing smaller than females.

Cephalothorax The cephalothorax, also called prosoma in some groups, is a tagma of various arthropods, comprising the head and the thorax fused together, as distinct from the abdomen behind. (The terms ''prosoma'' and ''opisthosoma'' are equivalent to ''cepha ...

and legs are reddish to dark brown and the abdomen is dark to light grey with fine hairs, often appearing with large, bilaterally mirrored paler spots. Males feature large, extended palps with prominent projections. It is a nesting woodland species commonly seen in the Pacific Northwest, and one of the most commonly found and widespread spiders in populated areas of Washington state. It can often be found in households and other man-made structures with thin funnel webs, so long as the niche has not yet been filled by another organism. The species poses no threat to humans or pets,Akre, Roger D. and Catts, Paul E.
EB1548: Spiders
Washington State University. though like other ''

Callobius ''Callobius'' is a genus of tangled nest spiders first described by R. V. Chamberlin in 1947. Species it contains thirty-one species with a holarctic The Holarctic realm is a biogeographic realm that comprises the majority of habitats fo ...

'' species, the bite is painful.

References

Amaurobiidae Spiders of North America Spiders described in 1884 {{Amaurobiidae-stub