Cambridgea Explained

Cambridgea (common name New Zealand sheetweb spider, bush spider) is a spider genus in the family Desidae and some of the first endemic spiders described from New Zealand.[1] They are known for constructing large horizontal sheet webs measuring up to a square metre in larger species.[2] Cambridgea were originally assigned to the Agelenidae[3] by Dalmas in 1917 but were reassigned to the Stiphidiidae in 1973.[4] Most recently, both Cambridgea and sister genus Nanocambridgea were reassigned to the Desidae, subfamily Porteriinae on the basis of molecular evidence.[5]

Description

Cambridgea are medium to large arboreal spiders, with body lengths ranging from approximately 6-10mm in the case of Cambridgea reinga to about 20mm in the case of Cambridgea foliata. They have long legs and porrect chelicerae which are significantly longer in adult males compared to adult females.[6] Male pedipalps are characterised by a cymbium that extends well beyond the bulb and species can be differentiated by the morphology of the male tibial apophyses and female epigyne.[7]

Behaviour

Male-male competition

In the summer, following maturation, adult males depart their natal webs at night and wander in search of receptive females. During this time males will frequently wander into homes, sometimes getting stuck in bathtubs.[8] Having found a female's web, males will defend the web and fight any rival males that subsequently arrive in her web. Fights proceed through clear stages of escalation. In some species males will first signal to each other by creating distortions in the mainsheet by shaking their bodies or by drumming their first pairs of legs and pedipalps on the web. Unless one male withdraws from the web, these contests will escalate to sparring, in which males push at each other with their first two pairs of legs. Some fights will escalate further into grappling in which males lock their chelicerae together and push against one another. Fights rarely result in injury.[9]

Web building

Cambridgea are known for building characteristic, three-dimensional sheet webs consisting of a thick, horizontal mainsheet guyed from below with anchoring threads and with a large number of knock-down threads above the mainsheet to intercept flying insects. The "rear" of the web attaches to a silken retreat which extends a short distance into crevices.[10] The size of webs can vary significantly. Some species build sheet webs with mainsheets of up to one square metre, while some species (e.g. Cambridgea quadromaculata) do not build webs at all.[11] Those Cambridgea that do build webs run along the underside of the mainsheet rather than along the top as some sheet-web spiders do (e.g. Corasoides).

Species

, the World Spider Catalog accepted the following species.

See also

Notes and References

  1. White. A. 1849. Descriptions of apparently new species of Aptera from New Zealand. Proceedings of the Zoological Society of London. 6.
  2. Book: Spiders of New Zealand : annotated family key & species list. Paquin, Pierre. 2010. Manaaki Whenua Press. Vink, C. J. (Cornelis Jacob), Dupérré, N. (Nadine). 9780478347050. Lincoln, N.Z.. 608025036.
  3. Dalmas. R. 1917. Araignées de Nouvelle-Zélande. Annales de la Société Entomologique de France. 86. 317–430.
  4. Book: Forster, RR. The spiders of New Zealand. Part 4, Agelenidae, Stiphidiidae, Amphinectidae, Amaurobiidae, Neolanidae, Ctenidae, Psechridae. Wilton. CL. Otago Museum Trust Board. 1973. Dunedin.
  5. Wheeler. Ward C.. Coddington. Jonathan A.. Crowley. Louise M.. Dimitrov. Dimitar. Goloboff. Pablo A.. Griswold. Charles E.. Hormiga. Gustavo. Prendini. Lorenzo. Ramírez. Martín J.. 2016-12-12. The spider tree of life: phylogeny of Araneae based on target-gene analyses from an extensive taxon sampling. Cladistics. en. 33. 6. 574–616. 10.1111/cla.12182. 0748-3007. free.
  6. Forster, R.R.; Wilton, C.L. 1973. The spiders of New Zealand. Part 4, Agelenidae, Stiphidiidae, Amphinectidae, Amaurobiidae, Neolanidae, Ctenidae, Psechridae. Otago Museum Bulletin, 4: p. 148.
  7. Blest, A.D.; Vink, C.J. 2000: New Zealand spiders: Stiphidiidae. Records of the Canterbury Museum, 13(supplement)
  8. Book: Crowe, Andrew. Which New Zealand spider? : including their eight-legged cousins: the harvestmen, false scorpions, mites, ticks and sea spiders. 2007. Penguin. 9780143006435. North Shore, N.Z.. 166343598.
  9. Walker. Leilani A.. Holwell. Gregory I.. 2018. The role of exaggerated male chelicerae in male–male contests in New Zealand sheet-web spiders. Animal Behaviour. 139. 29–36. 10.1016/j.anbehav.2018.02.020. 0003-3472.
  10. Book: New Zealand spiders : an introduction. Forster.. Raymond R.. Forster. Lyndsay M.. 1973. Collins. 978-0002115650. Auckland. 829317.
  11. Blest. A. D.. Taylor. P. W.. 1995. Cambridgea quadromaculata n. sp. (Araneae, Stiphidiidae): A large New Zealand spider from wet, shaded habitats. New Zealand Journal of Zoology. 22. 3. 351–356. 10.1080/03014223.1995.9518051. 0301-4223. free.

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