Grass spider

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American Grass Spiders
A. pennsylvanica female in web
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Arachnida
Order: Araneae
Family: Agelenidae
Genus: Agelenopsis
Giebel, 1869
Species

see text

Diversity
13 species

The American grass spiders are members of the genus Agelenopsis. They weave sheet webs that have a funnel shelter on one edge. The web is not sticky, but these spiders make up for that shortcoming by running very rapidly. The larger specimens (depending on species) can get up to approximately 19 mm in body length. They may be recognized by the arrangement of their eight eyes into three rows. The top row has two eyes, the middle row has four eyes, and the bottom row has two eyes (spaced wider than the ones on the top row). They also have two prominent hind spinnerets, and somewhat indistinct bands on their legs. They also have two dark bands running down either side of the cephalothorax.

Agelenopsis aperta, the American funnel-web spider, produces agatoxins. Their bite causes rapid paralysis in insect prey, although the spider's Chelicerae are too small to penetrate human skin.

Name

The genus name is a combination of Agelena (Eurasian grass spiders) a genus of similar spiders, and Greek -opsis "to look like". They are harmless spiders. Although most spiders use their webs to catch prey, the grass spider's web lacks adhesive ability. The spiders make up for that with their fast running.

The main distinction between Agelenopsis and its European cousin genus Agelena consists of the pattern appearing on the cephalothorax: the former possess two quasi-parallel lines from the eyes to the beginning of the abdomen. The latter ones have lines that are curved, irregular and often meet at the end. Another difference is the length of the front legs row in females, however, in males the comparison is too inconsiderable.

Species

  • Agelenopsis actuosa (Gertsch & Ivie, 1936) (USA, Canada) – Common American Funnel-web Spider or Canadian Funnel-web Spider
  • Agelenopsis aleenae Chamberlin & Ivie, 1935 (USA)
  • Agelenopsis aperta (Gertsch, 1934) (USA, Mexico) – Desert Grass Spider or North American Funnel-web Spider
  • Agelenopsis emertoni Chamberlin & Ivie, 1935 (USA)
  • Agelenopsis kastoni Chamberlin & Ivie, 1941 (USA)
  • Agelenopsis longistyla (Banks, 1901) (USA)
  • Agelenopsis naevia (Walckenaer, 1842) (USA, Canada)
  • Agelenopsis oklahoma (Gertsch, 1936) (USA)
  • Agelenopsis oregonensis Chamberlin & Ivie, 1935 (USA)
  • Agelenopsis pennsylvanica (C. L. Koch, 1843) (USA) – Pennsylvania Grass Spider
  • Agelenopsis potteri (Blackwall, 1846) (North America, introduced in Russia)
  • Agelenopsis spatula Chamberlin & Ivie, 1935 (USA)
  • Agelenopsis utahana (Chamberlin & Ivie, 1933) (USA, Canada, Alaska)

Other pictures

  • Agelenopsis sp. male, 17 mm (about ¾ inch)

  • Same, showing elaborate pedipalps

  • Same, from the side.

  • Agelenopsis sp. showing pronounced leg spines.

  • Agelenopsis in its web.

  • Agelenopsis in web built on grass, with prey.

References

See also

Funnel-Web Spider

External links

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