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Cyclocosmia truncata.jpg
Cyclocosmia truncata
Scientific classification e
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Chelicerata
Class: Arachnida
Order: Araneae
Infraorder: Mygalomorphae
Family: Halonoproctidae
Genus: Cyclocosmia
Ausserer, 1871
Type species
Mygale truncata
Hentz, 1841

See text

Cyclocosmia or "trapdoor spider" is a genus of spiders in the Halonoproctidae 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 disk. 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 disk 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 disk, 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]