Dolomedes aquaticus is a species of fishing spider that lives and hunts along the gravel banks of unforested New Zealand rivers. It prefer open riverbanks where it typically lives under rocks, usually less than 5 metres away from the river. Its colouring allows it to camouflage against river stones. Normally nocturnal, it will sit and wait for prey after dark, and can survive for short periods under the water.
| Dolomedes aquaticus | |
|---|---|
| |
| Female with egg sac | |
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Subphylum: | Chelicerata |
| Class: | Arachnida |
| Order: | Araneae |
| Infraorder: | Araneomorphae |
| Family: | Pisauridae |
| Genus: | Dolomedes |
| Species: | D. aquaticus
|
| Binomial name | |
| Dolomedes aquaticus | |
Taxonomy
editDolomedes aquaticus was described in 1887 by Peter Goyen.[4]
Description
editFemales have a total body length of 13–26 mm, whilst males are typically smaller at 11–18 mm. The fourth leg is the longest, about 36 mm in females and 33 mm in males.[5] The cephalothorax is chocolate brown, with a supra-marginal band of yellow extending from the posterior slope to the anterior angle of the pars cephalica: falces, maxillæ, labium, and sternum chocolate-brown; legs and palpi, brown; abdomen above greenish-brown with two longitudinal rows of brown-margined yellow spots, at the sides greyish, and below dusky-brown with four more or less continuous longitudinal whitish stripes converging towards the anus. At the base of the dorsal surface there is a short median spathulate band of paler hue than the rest of that surface, and on each side of this band a short grey fleck. The cephalothorax and abdomen are densely covered with grey, yellow, and brown pubescence.[3]
Habitat and distribution
editDolomedes aquaticus usually live on open, stony riverbeds and rocky lake shorelines. D. aquaticus has been observed to be at its highest abundance when there is intermediate disturbance along the river banks.[6] D. aquaticus can be found throughout the South Island of New Zealand and in the lower half of the North Island of New Zealand.[5]It has been suggested that D. aquaticus is not present in the upper half of the North Island due to the lack of braided rivers in this region.[5]
Conservation status
editThis species is listed as "Not Threatened" in the New Zealand Threat Classification System (NZTCS).[1]
Behaviour
editDolomedes aquaticus is found on plants, stones or pieces of wood near the surface of the water. It can swim and run very rapidly on the water's surface. When provoked, it will flee towards the nearest object and may sometimes dive under the water, where it will remain until all danger is gone. Whilst incubating, the female migrates away from the water and lives under a large stone or piece of wood. She will remain here until the young have hatched. During incubation, the female will show considerable aversion to water. The cocoon is globular and is carried under the sternum, to which it is firmly held by the palpi and strands of web from the spinners.[3]
References
edit- ^ a b Sirvid, P.J.; Vink, C. J.; Fitzgerald, B. M.; Wakelin, M. D.; Rolfe, J.; Michel, P. (2020-01-01). "Conservation status of New Zealand Araneae (spiders), 2020". New Zealand Threat Classification Series. 34: 1–37.
- ^ "Taxon details Dolomedes aquaticus Goyen, 1888". World Spider Catalog. Natural History Museum Bern. Retrieved 2017-09-12.
- ^ a b c Goyen, P. (1887). "Art. XX.—Descriptions of new Species of New Zealand Araneae" (PDF). Transactions and Proceedings of the Royal Society of New Zealand. 20: 133–139. Retrieved 2017-09-12.
- ^ Goyen, P. (1888). Descriptions of new species of New Zealand Araneae. Transactions of the New Zealand Institute 20: 133-139.
- ^ a b c Vink, C. J. & Dupérré, Nadine (2010). "Dolomedes aquaticus Goyen". Pisauridae (Arachnida: Araneae) (PDF). Fauna of New Zealand. Vol. 64. pp. 23–24. Archived from the original (PDF) on 2017-05-19.
- ^ Greenwood, Michelle J.; McIntosh, Angus R. (2008). "Flooding Impacts on Responses of a Riparian Consumer to Cross-Ecosystem Subsidies". Ecology. 89 (6): 1489–1496. doi:10.1890/07-0749.1. ISSN 0012-9658. PMID 18589513. S2CID 14878786.
- Simon Pollard. Spiders and other arachnids, Te Ara - the Encyclopedia of New Zealand, updated 21-Sep-2007.
