Pimoa haden

Distinguished from other Pimoa species by subtle morphological characters requiring expert examination, including details of genitalia. The combination of relatively large body size (for Pimoidae), long legs, and fine net-like horizontal webs distinguishes it from the much smaller Linyphiidae (sheetweb weavers) to which Pimoidae were formerly assigned. Within the genus Pimoa, identification to species level requires examination of microscopic characters.

Medium-sized spider with long legs that increase its apparent size. Females measure 5-12 mm in body length, while males are smaller at approximately 5 mm. The body is relatively robust compared to the closely related sheetweb weavers (Linyphiidae). Coloration and detailed patterning are not specifically documented for this species.

Coniferous forests in rain shadow regions. Webs are constructed in crevices of logs, fences, and retaining walls. The species appears to favor shaded, moist microhabitats where dew helps make the nearly invisible webs detectable.

Western United States, specifically along the Pacific coast region. The species has been recorded from California and Oregon based on available distribution data.

Adults can be found hanging beneath webs at night or on overcast days. Specific seasonal activity patterns are not well documented, but the species is active during warmer months when prey availability supports web-building.

Females construct nearly spherical egg sacs covered with debris for camouflage, containing approximately 80-100 eggs. Juveniles emerge and presumably disperse to construct their own webs. Developmental stages and timing are not specifically documented for this species.

Constructs fine, net-like horizontal webs that may span up to one yard (approximately 0.9 meters) though most webs are smaller, typically under six inches across. The spider hides in a crevice or retreat during daylight hours and hangs from the underside of the web at night or during overcast conditions. Like related Linyphiidae, individuals may autotomize legs below the patellar segment to escape predators, with minimal impact on mobility.

Predator on small flying insects captured in the hammockweb. Serves as prey for larger invertebrates and possibly small vertebrates. Contributes to arthropod diversity in coniferous forest understory communities.

Not a species of economic importance. Occasionally encountered by naturalists and arachnologists in western North America. No known medical significance or pest status.

• Pimoa rupicolaAnother large Pimoa species in western North America; distinguished by geographic distribution and subtle morphological differences
• Linyphiidae (sheetweb weavers)Formerly classified together; distinguished by much smaller body size (typically under 5 mm) and different web architecture
• Nesticidae (cave cobweb spiders)May share crevice-dwelling habits; distinguished by different web structure (tangled cobwebs vs. fine sheet webs) and eye arrangement

• spider
• hammockweb
• Pacific coast
• coniferous forest
• nocturnal

• BugGuide
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Bug Eric: May 2015
• biodiversity | Blog - Part 34
• ID Challenge #14 | Beetles In The Bush