Opiliones (harvestmen)

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Harvestman. [Photo N. Larsen ©]

Harvestman. [Photo N. Larsen ©]

Opiliones are commonly called shepherd spiders, harvest spiders or harvestmen. 'Opilio' in Latin means shepherd and the name is probably derived from the fact that in earlier times, European shepherds sometimes walked on stilts to observe their flocks better and Opiliones look as if they are on stilts when walking. The term harvestmen or harvest spiders was a result of them being seen only during harvesting time. They are also referred to as daddy long legs but should not be confused with similarly named spiders, the Pholcidae. Opiliones are not spiders and have no spinning organs, fangs or venom glands and are harmless to man.

Opiliones are not well known as they and rarely seen due to their cryptic lifestyle. They live in damp forest areas under leaf-litter where they feed on small insects and other invertebrates, snails, fungi and dead animal and vegetable matter. They are more numerous at sea level and numbers diminish with altitude.

The head and thorax are not separated by narrow constriction as with spiders. They have round bulbous bodies and very long legs and generally small (bodies up to about 7 mm long). Their cryptic colouration affords protection from predators but should they be attacked, they are usually able to repel the attacker with a repugnant secretion from odiferous glands.

References

  • Bivort BL, Giribet G. 2010. A systematic revision of the South African Pettalidae (Arachnida : Opiliones : Cyphophthalmi) based on a combined analysis of discrete and continuous morphological characters with the description of seven new species. Invertebrate Systematics 24(4) 371-406. doi: 10.1071/IS10015
  • Boyer SL, Giribet G. 2007. A new model Gondwanan taxon: systematics and biogeography of the harvestman family Pettalidae (Arachnida, Opiliones, Cyphophthalmi), with a taxonomic revision of genera from Australia and New Zealand. Cladistics 23(4): 337-361.
  • Boyer SL, Giribet G. 2009. Welcome back New Zealand: regional biogeography and Gondwanan origin of three endemic genera of mite harvestmen (Arachnida, Opiliones, Cyphophthalmi). Journal of Biogeography 36(6): 1084-1099.
  • de Bivort BL, Clouse RM, Giribet G. 2010. A morphometrics-based phylogeny of the temperate Gondwanan mite harvestmen (Opiliones, Cyphophthalmi, Pettalidae). Journal of Zoological Systematics and Evolutionary Research 48: 294–309.
  • Giribet G. 2003. Karripurcellia, a new pettalid genus (Arachnida : Opiliones : Cyphophthalmi) from Western Australia, with a cladistic analysis of the family Pettalidae. Invertebrate Systematics 17(3): 387-406. doi:10.1071/IS02014
  • Kauri H. 1961. Opiliones. In South African Animal Life. Results of the Lund University Expedition in 1950–1951 (Eds B. Hanström, P. Brinck and G. Rudebeck.) pp. 9–197. Almquist & Wiksell, Uppsala.
  • Kury AB. 2006. A new species of Graemontia Lawrence, 1931, from the Western Cape, South Africa, with notes on the relationships of the genus (Opiliones: Laniatores: Triaenonychidae). African Zoology 41(1): 45–50.
  • Lawrence RF. 1931. The harvest-spiders (Opiliones) of South Africa. Annals of the South African Museum 29: 341–508.
  • Lawrence RF. 1933. The harvest-spiders (Opiliones) of Natal. Annals of the Natal Museum 7, 211–241.
  • Lawrence RF. 1939. A contribution to the opilionid fauna of Natal and Zululand. Annals of the Natal Museum 9, 225–243.
  • Lawrence RF. 1963. The Opiliones of the Transvaal. Annals of the Transvaal Museum 24, 275–304.
  • Lawrence RF. 1981. South African Harvest Spiders. The Naturalist. 25(3): 13-27.
  • Lotz LN. 2009. Harvestman (Arachnida: Opiliones) in southern Africa - an annotated catalogue with notes on distribution. Navorsinge van die Nasionale Museum, Bloemfontein 25(1): 1- 46.
  • Schönhofer AL. 2008. On harvestmen from the Soutpansberg, South Africa, with description of a new species of Monomontia (Arachnida: Opiliones). African Invertebrates 49(2): 109-126.
  • Sharma PP, Giribet G. 2011. The evolutionary and biogeographic history of the armoured harvestmen – Laniatores phylogeny based on ten molecular markers, with the description of two new families of Opiliones (Arachnida). Invertebrate Systematics 25(2): 106-142. doi: 10.1071/IS11002
  • Starega W. 2008. The second species of Purcellia Hansen et Sørensen, 1904 (Arachnida: Opiliones: Pettalidae) from South Africa. Polish Journal of Entomology 77, 51–56.

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Text by Norman Larsen ©.


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