Dolomedes schauinslandi

Dolomedes schauinslandi
Rangatira spider on Mangere Island, New Zealand
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Arachnida
Order: Araneae
Family: Pisauridae
Genus: Dolomedes
Species: D. schauinslandi
Binomial name
Dolomedes schauinslandi
(Simon, 1899)[1]

Dolomedes schauinslandi or Rangatira spider is a large spider of the family Pisauridae. It is only found on Rangatira, Houruakopara and Mangere Island in the Chatham Islands, New Zealand. It is one of New Zealand's largest and rarest spiders.[2]

Description

This large Dolomedes spider was first described by Eugène Simon in 1899 as "one of the biggest and most robust species of the genus Dolomedes".[1] This species demonstrates sexual dimorphism with male body lengths measured from 18.6-26.0 mm and females from 23.3-30.2 mm. Both males and females are substantially larger than other New Zealand Dolomedes species. The carapace and legs are red-brown with orange stripes on the centre and sides of the abdomen.[3]

Ecology

D. schauinslandi is active at night in forest and scrubland habitat where it feeds on weta.[3] Its predators could include mice and weka, which could explain its absence from Pitt Island, where it was described as common in the original species description.[1] Mating has not been observed, but females have been observed carrying eggsacs in their chelicerae in November and December and guarding their nursery from December to February, as would be expected for a nursery web spider.[3]

Conservation

This species is classified as having a relict population status. This is due to it remaining in less than 10% of its previously known habitat.[4] Its former range included Pitt Island, where is has not been seen despite substantial surveys. It was probably present on the main Chatham Island prior to human settlement, as it is found on the nearby Houruakopara Island.[3] Two of the islands in its current range, Mangere and Rangatira, are now free of introduced mammals and have restricted access to maintain their predator free status.[5] It is possible that this species could re-establish itself on Pitt Island, if there was suitable predator-free habitat, due to the fact that it has been observed to display behaviours associated with ballooning.[3]

References

  1. 1 2 3 Simon, Eugène (1899). "Ergebnisse einer Reise nach dem Pacific (Schauinsland 1896-1897). Arachnoideen". Zoologische Jahrbücher. 12: 436. Retrieved 3 August 2017.
  2. ↑ Sirvid, Phil. "Island spiders dwarf cousins". PressReader. Dominion Post. Retrieved 7 August 2017.
  3. 1 2 3 4 5 Vink, C.J. (2010). "Fauna of New Zealand Pisauridae (Arachnida: Araneae)" (PDF). Fauna of New Zealand (64). Retrieved 3 August 2017.
  4. ↑ Sirvid, P. J.; Vink, C. J.; Wakelin,, M. D.; Fitzgerald,, B. M.; Hitchmough, R. A.; Stringer, I. A.N. (2012). "The conservation status of New Zealand Araneae". New Zealand Entomologist. 35 (2): 86–87. doi:10.1080/00779962.2012.686310. Retrieved 7 August 2017.
  5. ↑ "Mangere and Rangatira islands". Department of Conservation. Retrieved 7 August 2017.
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