Erigoninae

dwarf spiders, money spiders

Genus Guides

63

Erigoninae is the largest of Linyphiidae (sheet-web weavers), itself the second largest spider . These minute spiders are commonly called dwarf spiders in the United States and money spiders in England. The subfamily contains over 2,000 described , making it the most numerous group within the sheet-web weavers. Many species inhabit leaf litter and construct small sheet webs, while others occupy diverse terrestrial from coastal dunes to alpine timberlines.

Diplocephalus by (c) Steve Kerr, some rights reserved (CC BY), uploaded by Steve Kerr. Used under a CC-BY license.Ceraticelus artemisiae by (c) Toby, some rights reserved (CC BY), uploaded by Toby. Used under a CC-BY license.Ceraticelus artemisiae by (c) Toby, some rights reserved (CC BY), uploaded by Toby. Used under a CC-BY license.

Pronunciation

How to pronounce Erigoninae: /ˌɛrɪˈɡoʊnɪniː/

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Identification

Erigoninae are distinguished from other Linyphiidae by their extremely small body size—most measure under 2 mm, with some less than 1 mm and very few reaching 6 mm. Males frequently exhibit bizarre cephalic projections including lobes, turrets, grooves, pits, and modified hairs; these structures are presumed to function in courtship. The is taxonomically challenging, with exact limits not yet fully resolved. Species-level identification typically requires examination of genitalia and is often impossible without mature specimens.

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Habitat

Many occupy leaf litter and build minute sheet webs. Others have been documented in diverse including coastal grey dunes, alpine timberlines, forest habitats, heavily grazed pastures, and wetland edges. The Esophyllas comprises litter-dwelling species from southern California, while Caracladus species occur at alpine timberlines and in forest habitats.

Distribution

Erigoninae are the spider group of temperate and cold regions of the Northern Hemisphere. More than 300 occur in northern Europe, comprising about one-fourth of the spider fauna there. Approximately 650 species are known from North America. Diversity decreases in the Southern Hemisphere; no native species have been recorded from New Zealand or Australia. The is less diverse in tropical regions.

Seasonality

dwarf spiders have been observed ballooning during winter months. Spring activity has been documented in temperate regions, with spiders emerging from sites. Erigonidium graminicolum develops successfully across temperatures from 15°C to 32°C, with pre-imaginal development ranging from 94.4 days at 15°C to 23.8 days at 32°C.

Diet

Erigoninae are predatory spiders that capture small arthropods in their sheet webs. Stenotopic dwarf spiders in coastal grey dunes have been documented in association with isotomid collembolans as prey, though whether this represents active prey selection or shared microhabitat preference remains unresolved.

Life Cycle

Erigonidium graminicolum exhibits temperature-dependent development with distinct stages: , , and . At 35°C, all eggs died before hatching. Juvenile development time decreases with temperature up to 32°C, then increases at 35°C. Males and females show statistically significant differences in juvenile and pre-imaginal development times. averaged as Type III across temperatures.

Behavior

Both spiderlings and balloon to disperse, climbing to elevated positions, releasing silk threads, and becoming airborne on wind currents or electrostatic forces. This facilitates of islands and disturbed . Females of some grip male cephalic pits or grooves with their during copulation, then ingest secretions from male prosomic glands after depositing saliva-like fluid on them. One species, Atypena formosana, lives colonially in wetland habitats, building nets just above water lines in rice fields to hunt planthopper nymphs.

Ecological Role

Erigoninae likely serve as important members of beneficial complexes in agroecosystems, though their contribution is generally underrecognized due to their minute size. Their high abundance in northern European spider faunas suggests significant predatory impact on microarthropod . As early colonizers of disturbed and islands, they contribute to reassembly after natural disasters.

Human Relevance

Erigoninae have no direct economic importance to humans. Their minute size renders them inconspicuous and they are not known to bite humans or cause property damage. Their "money spiders" in England reflects a folk belief that finding one brings financial good fortune.

Similar Taxa

  • LinyphiinaeBoth are of Linyphiidae; Erigoninae are distinguished by smaller body size, more frequent male cephalic modifications, and different genitalic structures. Linyphiinae generally lack the bizarre male cephalic projections characteristic of many Erigoninae.
  • other Linyphiidae subfamiliesErigoninae is the most -rich ; other subfamilies typically contain larger-bodied sheet-web weavers with different web architectures and less extreme in cephalic structure.

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