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The Archaeidae are a spider family with 25 described species in three genera.
Their common name pelican spider stems from their specialised anatomy: They evolved elongated jaws and neck for catching other spiders.
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Distribution
Archaeidae occur in South Africa, Madagascar and Australia. The Archaea are a Gondwana group.
Assassin spiders
Assassin spiders are a group of spiders of the family Archaeidae, which are extremely unusual in that they have very long necks vertically separating their head from their thorax by nearly the length of their body itself. They prey upon other spiders, snagging them by surprise with fangs that are proportionately many times larger than those of any other spider. Assassin spiders were first known from 40 million year old examples trapped in amber, which were found in Europe in the 1840s, and were not known to have living varieties until 1881. They are native to Australia and Africa (including Madagascar), with one species occurring in South America. They are only known to grow to 6 mm (1/4 inch) in size[1]. They may be small, but Assassin spiders are among the most dangerous spiders on the planet – if you’re another spider, that is. These tiny arachnids in the Archaeidae family are only about 2 mm (less than 1/8 inch) long, but their bizarre fangs and spider-hunting practices have earned them a reputation as the world’s most grotesque spiders. They hunt by stabbing their prey with venom-filled fangs that are attached to the ends of extremely elongated jaws. These specialized jaws are about ten times longer than the jaws of most other spiders their size. To support these long jaws and prevent them from dragging along the ground, Assassin spiders have also evolved elongated necks. The combination allows them to strike their prey without having to approach too closely.
The fossil record shows that Assassin spiders were once widely distributed across the planet, but today they are known only from Australia, South Africa, and Madagascar. Until recently, only about a dozen species were recognized. However, nine new species are about to be added to the list, almost doubling the known members of the family. For the past few years, Academy entomologist Charles Griswold and San Francisco State University graduate student Hannah Wood have been working to document the spiders of Madagascar as part of the Academy’s ongoing arthropod survey of the country. Since the survey was started in 2000, over 2 million arthropod specimens have been processed. Among them, Griswold and Wood noticed a number of tiny Archaeidae spiders that looked suspiciously like new species.
Wood conducted molecular and morphological studies and found that nine new species of Assassin spiders were included in the specimens from Madagascar. Surprisingly, the DNA data also revealed that the presence of elongated necks among Archaeidae spiders had evolved at least two separate times. A classic example of convergent evolution, her findings suggest that the need to strike out at prey from a distance encouraged the evolution of extended body parts on more than one occasion.
Species
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- Afrarchaea Forster & Platnick, 1984
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- Afrarchaea bergae Lotz, 1996 — South Africa
- Afrarchaea entabeniensis Lotz, 2003 — South Africa
- Afrarchaea fernkloofensis Lotz, 1996 — South Africa
- Afrarchaea fisheri Lotz, 2003 — Madagascar
- Afrarchaea godfreyi (Hewitt, 1919) — South Africa, Madagascar
- Afrarchaea haddadi Lotz, 2006 — South Africa
- Afrarchaea harveyi Lotz, 2003 — South Africa
- Afrarchaea kranskopensis Lotz, 1996 — South Africa
- Afrarchaea lawrencei Lotz, 1996 — South Africa
- Afrarchaea mahariraensis Lotz, 2003 — Madagascar
- Afrarchaea ngomensis Lotz, 1996 — South Africa
- Afrarchaea royalensis Lotz, 2006 — South Africa
- Afrarchaea woodae Lotz, 2006 — South Africa
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- Austrarchaea Forster & Platnick, 1984
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- Austrarchaea daviesae Forster & Platnick, 1984 — Queensland
- Austrarchaea hickmani (Butler, 1929) — Victoria
- Austrarchaea mainae Platnick, 1991 — Western Australia
- Austrarchaea nodosa (Forster, 1956) — Queensland
- Austrarchaea robinsi Harvey, 2002 — Western Australia
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- Eriauchenius O. P.-Cambridge, 1881
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- Eriauchenius bourgini (Millot, 1948) — Madagascar
- Eriauchenius cornutus (Lotz, 2003) — South Africa
- Eriauchenius gracilicollis (Millot, 1948) — Madagascar
- Eriauchenius jeanneli (Millot, 1948) — Madagascar
- Eriauchenius legendrei (Platnick, 1991) — Madagascar
- Eriauchenius pauliani (Legendre, 1970) — Madagascar
- Eriauchenius ratsirarsoni (Lotz, 2003) — Madagascar
- Eriauchenius tsingyensis (Lotz, 2003) — Madagascar
- Eriauchenius vadoni (Millot, 1948) — Madagascar
- Eriauchenius workmani O. P.-Cambridge, 1881 — Madagascar
- Jurarchaeinae Eskov, 1987 † (fossil)
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- Jurarchaea Eskov, 1987 †
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- Jurarchaea zherikhini Eskov, 1987 †
See also
References
- Penney D. (2003) Afrarchaea grimaldii, a new species of Archaeidae (Araneae) in Cretaceous Burmese amber. Journal of Arachnology 31, 122-130. PDF
- Platnick, Norman I. (2008): The world spider catalog, version 8.5. American Museum of Natural History.
External links
- "Tiny Assassins" at California Academy of Sciences
- National Geographic Photo in the News: Bizarre Assassin Spiders Discovered in Madagascar
- Large image of Eriauchenius gracilicollis
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Wikipedia content modification information:
- This page was last modified on 28 August 2008, at 06:30.
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