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Female Sphodros abbotii (Purse-web spider) Photo by Ben Stegenga. Image may be subject to copyright.
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Sphodros abbotii Walckenaer, 1835

Purse-web spider

Federal Protection: No US federal protection

State Protection: No Georgia state protection

Global Rank: G4G5

State Rank: S2

SWAP High Priority Species (SGCN): Yes

Element Occurrences (EOs) in Georgia: 8

Habitat Summary for element in Georgia: Hardwoods


Description

In mygalomorph spiders like Sphodros abboti, large chelicerae/fangs are vertically oriented parallel. Females, dark brown to black in color, are robust and fairly large (19 mm [0.7 inches] in total length). Mature males are slightly smaller and have iridescent, gun-metal blue abdomens. The posterior spinnerets are comprised of four joints.

Similar Species

A second purseweb spider, Sphodros rufipes (red-legged purseweb spider), is of general occurrence throughout the Georgia (and Florida) range of S. abboti, although the two species typically do not occupy the same sites. In S. rufipes, the posterior spinnerets are three-jointed (four-jointed in S. abboti). The size and placement of the sigilla may also be used to distinguish the two species (see Gertsch and Platnick 1980). Female S. rufipes are larger (to 25 mm); mature male S. rufipes are black with bright red legs.

Habitat

: Restricted to mesic hardwood forests, including hammocks and slope forests. Slope forests, characterized by a canopy of oaks (Quercus alba [white oak], Q. michauxii [swamp chestnut oak]), American beech (Fagus grandifolia), and southern magnolia (Magnolia grandiflora), are uncommon, highly localized environments limited to steep, usually north-facing slopes or bluffs. Blue purseweb spiders are absent from habitats historically subject to frequent fire and from forests on previously farmed sites now characterized by low plant species diversity.

Diet

These spiders, accomplished sit-and-wait predators, feed on a wide variety of other arthropods.

Life History

Blue ourseweb spiders construct distinctive, persistent, tube-like webs that begin below ground and extend 10-30 cm up the base of a tree. Webs are attached to a wide variety of deciduous and evergreen hardwood tree species. The outer portion of the tube is camouflaged with bits of lichen and bark. Prey, including millipedes, are attacked through the tube; the spider then cuts a slit in the tube (so that it can bring its prey item inside the tube to finish killing/consuming it); then the spider patches the slit. Sphodros abboti often occurs in very high densities (much higher than S. rufipes). The greater density of S. abboti (up to several hundred tubes per hectare, often with multiple tubes [up to a dozen] on the same tree) suggests a sedentary, non-ballooning life style. Ballooning has been reported for S. rufipes, but not for S. abboti. Oviposition occurs around August, with reported brood size ranging from 49-142 eggs. Spiderlings may overwinter in their mother's web prior to dispersing the following spring. The metallic blue males are thought to be wasp mimics. Blue purseweb spiders are slow to mature and especially long-lived (likely reaching ages of 5-10 plus years in the wild).

Survey Recommendations

A recent field survey described the overall range-wide distribution of this species. It is likely that additional sites for S. abboti remain to be discovered within its limited distribution in Georgia. Conducting visual surveys for the distinctive tubular webs of these spiders is an effective sampling method and long-term monitoring of some spider populations should be initiated.

Range

A Coastal Plain species found in extreme south-central Georgia and throughout the northern third of Florida. In Georgia, S. abboti is known from six counties close to the Florida state line (Brooks, Echols, Grady, Lanier, Lowndes, and Thomas). Records are documented for the Valdosta Limesink and Red Hills physiographic provinces, with the north-most known sites close to Lakeland, Georgia.

Threats

Wild pigs are present at some of the known sites for this spider in Georgia, and pig control/eradication should be undertaken. The steep slopes of some blue purseweb spider habitats make logging impractical; regardless, logging of spider sites is apt to result in damage to these diverse hardwood habitats and shouldn’t be conducted.

Georgia Conservation Status

There are very few sites (7 total) known for Georgia, with six of these discovered from 1998-2018. A significant population found at Dudley’s Hammock on Moody Air Force Base is protected.

Conservation Management Recommendations

Additional Georgia surveys for this spider are warranted. Control of wild pigs and invasive plants should be conducted at sites known to support this spider.

References

Bishop, S.C. 1950. The purse-web spider, Atypus abboti (Walckenaer), with notes on related species. (Arachnida:Atypidae). Entomological News, 61(5):121 ̶ 124.

Coyle, F.A. 2017. Chapter 5: Atypidae. Pp. 49−50, In D. Ubick, P. Paquin, P.E. Cushing, and V. Roth (Eds.). Spiders of North America: an Identification Manual, Second Edition. American Arachnological Society, Keene, NH. 425 pp.

Coyle, F.A., and W.A. Shear. 1981. Observations on the natural history of Sphodros abboti and Sphodros rufipes (Araneae, Atypidae), with evidence for a contact sex pheromone. Journal of Arachnology, 9:317 ̶ 326.

Gertsch, W.J., and N.I. Platnick. 1980. A revision of the American spiders of the family Atypidae (Araneae, Mygalomorphae). American Museum Novitates, 2704:1 ̶ 39.

Moler, P.E., D. Stevenson, B.W. Mansell, J. Mays, and C.W. Lee. Distribution and Natural History of the Purseweb Spiders Sphodros abboti and S. rufipes (Araneae: Mygalomorphae: Atypidae) in Florida, Georgia, and Alabama. Southeastern Naturalist. Submitted.

Wallace, H.K., and G.B. Edwards. 1994. Rare: Blue purseweb spider Sphodros abboti Walckenaer; Red-legged purseweb spider Sphodros rufipes (Latreille). Pp. 247 ̶ 249, In M. Deyrup and R. Franz (Eds.). Rare and Endangered Biota of Florida Vol. IV. Invertebrates. University Press of Florida, Gainesville. 798 pp.

Authors of Account

Dirk J. Stevenson

Date Compiled or Updated

1 December 2018

Male Sphodros abbotii (Purse-web spider) Photo by Daniel Dye. Image may be subject to copyright.