Purseweb spiders are a family of spiders that build tubelike webs; in our area, these webs are usually 6–10 inches long and positioned vertically against the base of a tree. At a glance, the web may look like a small branch leaning against the tree trunk. The spider hides within its tube, waiting for prey. For this reason, purseweb spiders are not often seen; when people do notice purseweb spiders, it is usually males that are wandering around on the ground, seeking mates. Males’ gender can be verified by noting the enlarged, clublike pedipalps to each side of the large chelicerae (fangs).
Species: Eight species of purseweb spiders occur in North America north of Mexico: 7 in genus Sphodros, and 1 in genus Atypus (before 1980, all were placed in genus Atypus). Of the 8, apparently only 3 species in genus Sphodros occur in Missouri; the rest have distributions that don’t include our state.
The redlegged purseweb spider (Sphodros rufipes; previously called Atypus bicolor) is Missouri’s most common purseweb species. It is most abundant south of the Missouri River. Like most other purseweb spiders, it resembles a sturdy running spider but is glossy and has exceptionally large chelicerae. The overall color of males is shiny black with bright reddish-orange legs. Females, less likely to be seen because they usually stay hidden in their camouflaged webs, are shiny dark reddish brown with blackish grooves and depressions, with a dull brownish abdomen.
Fitch’s purseweb spider (S. fitchi) is also found in Missouri; its overall range includes states to our north, west, and south. It is similar to S. rufipes, except the males of S. fitchi have orange (not red) coloration, which is only on the top surface of the outermost leg segments, starting only on the outermost tip of the femur segment. In 2018 this species was found on a prairie in southwestern Missouri.
The black purseweb spider (S. niger) is another species with a rather wide range, extending from the northeastern United States west to Wisconsin and Kansas, north to Ontario, and south to Tennessee. It is all glossy black, except for a gray or pale bluish band crossing the head at the base of the chelicerae.