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Cyclocosmia truncata
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Arachnida
Order: Araneae
Family: Ctenizidae
Genus: Cyclocosmia
Ausserer, 1871
Type species
Mygale truncata
Hentz, 1841

See text.

7 species

Cyclocosmia or "trapdoor spider" is a genus of spiders in the Ctenizidae family.

The abdomen of spiders in this genus is abruptly truncated and ends in a hardened disc which is strengthened by a system of ribs and grooves. They use this to clog the entrance of their 7 to 15 cm deep vertical burrows when threatened,[1] a phenomenon called phragmosis. Strong spines are located around the edge of the disc. The four spinnerets are found just anterior to it, with the posterior, retractable spinnerets particularly large. C. ricketti females are 28 mm long, with a disc diameter of 16 mm. Only the bottom portion of the burrow is silk lined.[2]

The species in this genus are distinguished from each other by the pattern of the abdominal disc, the number of hairs on its seam, and the shape of the spermathecae.



  1. ^ Zhu et al. 2006
  2. ^ Murphy & Murphy 2000


  • Murphy, Frances & Murphy, John (2000): An Introduction to the Spiders of South East Asia. Malaysian Nature Society, Kuala Lumpur.
  • Zhu, M.S., Zhang, J.X & Zhang, F. (2006): Rare spiders of the genus Cyclocosmia (Arachnida: Araneae: Ctenizidae) from tropical and subtropical China. The Raffles Bulletin of Zoology 54(1): 119-124 PDF (with pictures)
  • Platnick, Norman I. (2008): The world spider catalog, version 8.5. American Museum of Natural History.

Further reading[edit]

  • Schwendinger, Peter J. (2005): Two new Cyclocosmia (Araneae: Ctenizidae) from Thailand. Revue Suisse de Zoologie 112(1): 225-252

External links[edit]