Uloborus diversus
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adult female, live; body shape is a diagnostic feature |
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adult male, live |
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female genitalia; epigynum |
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male genitalia; palp, lateral view |
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male genitalia; palp, ventral view |
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grape size comparison with adult spiders; male (left), female (right) |
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spiderlings, dead; dorsal (left), ventral (right) |
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egg sac |
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egg sacs with scale (cm) |
Current valid name
Uloborus diversus Marx (family Uloboridae)
Recognition and diagnostic features
Uniquely shaped abdomen, makes orb-web in horizontal or slanted plane.
Spider
Body lengths when mature: male: 2.4 mm (range 2.1 to 2.7), female: 4 mm (range 3.2 to 4.7)
Immatures resemble miniature adults.
Egg sac
Description: suspended in web, very odd shape with projections around perimeter and little spicules attached to surface, looks like a tanned cowhide or the cell body portion of a neuron
Number of eggs per sac: 29.8 ± 15.3
Size of egg: 0.74 ± 0.028 mm
Time of year eggs are likely to be laid: found in April
Distribution
In California: most of state except northern counties
Elsewhere: Arizona, Utah, Nevada. Mexico
Native to North America
This species has not been transported or become established outside of its range.
Biology
Orb weavers. Often found around and inside homes. Often make a horizontal or slanted orb web, unlike the typically vertical orb web of the Araneidae. Extremely rare in grapes.
Status in table grapes
Level of Incidence: very rare
Level of Concern in New Zealand: WPNZ (May 2010) nr, BORIC (Dec 2011) nr (not listed), MAF-BPRA (2002) nr (coding definition)
Level of Concern in Australia: WPAU (2006) nr (coding definition)
Level of Medical importance: none, this is one of the unique spider families lacking venom glands
Common name
None for species, hackled orbweavers for family
Taxonomic history
Stable
Selected references
Muma, M. H., and W. J. Gertsch. 1964. The spider family Uloboridae in North America North of Mexico. Amer. Mus. Novit. #2196, 43 pp.
