Overview

Brief Summary

Taxonomy

Morphology


Diagnostic description
  • A medium sized species usually well marked with distinctive pattern on abdomen.
  • A distinct cream or whitish band around the front of the abdomen is almost always present
  • Legs usually red or reddish and usually serves to separate this form other species of Steatoda at a quick glance


Lookalikes
Other species of Steatoda and some other larger species of theridiid spider.
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Introduction

Steatoda nobilis is one of a group of spiders commonly known as false widow spiders (genus Steatoda) because of their general resemblance to the more notorious black widow spiders (genus Latrodectus).Steatoda nobilis has been established near the south coast of England for over a century with strongholds on the Dorset and Hampshire coast.The false widow spider is thought to be repeatedly reintroduced at ports in imports of bananas.The similarity to the notorious black widow spiders means often cause concern when found in and around homes in the UK.
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Comprehensive Description

Steatoda nobilis (Thorell, 1875)

Materials

Type status: Other material. Occurrence: sex: 1 female; Location: locationID: 4; higherGeography: Macaronesia; continent: Europe; waterBody: Atlantic Ocean; islandGroup: Madeira archipelago; island: Madeira; country: Portugal ; countryCode: PT; stateProvince: Madeira; county: Santana; locality: Faja da Nogueira - Mtdo. do Leacoque ; verbatimElevation: 630; decimalLatitude: 32.7415 ; decimalLongitude: -16.9161 ; geodeticDatum: WGS84; Event: samplingProtocol: Direct sampling

Ecological interactions

Native status

native

Distribution

Madeira archipelago, Canary Islands (elsewhere, introduced)

  • Crespo, Luis C., Boieiro, Mario, Cardoso, Pedro, Aguiar, Carlos A. S., Amorim, Isabel R., Barrinha, Carla, Borges, Paulo A. V., Menezes, Dilia, Pereira, Fernando, Rego, Carla, Ribeiro, Servio, Silva, Israel F., Serrano, Artur R. M. (2014): Spatial distribution of Madeira Island Laurisilva endemic spiders (Arachnida: Araneae). Biodiversity Data Journal 2, 1051: 1051-1051, URL:http://dx.doi.org/10.3897/BDJ.2.e1051
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Steatoda nobilis (Thorell, 1875)

Materials

Type status: Other material. Occurrence: sex: 1 female; Location: locationID: 4; higherGeography: Macaronesia; continent: Europe; waterBody: Atlantic Ocean; islandGroup: Madeira archipelago; island: Madeira; country: Portugal ; countryCode: PT; stateProvince: Madeira; county: Santana; locality: Faja da Nogueira - Mtdo. do Leacoque ; verbatimElevation: 630; decimalLatitude: 32.7415 ; decimalLongitude: -16.9161 ; geodeticDatum: WGS84; Event: samplingProtocol: Direct sampling

Ecological interactions

Native status

native

Distribution

Madeira archipelago, Canary Islands (elsewhere, introduced)

  • Crespo, Luis C., Boieiro, Mario, Cardoso, Pedro, Aguiar, Carlos A. S., Amorim, Isabel R., Barrinha, Carla, Borges, Paulo A. V., Menezes, Dilia, Pereira, Fernando, Rego, Carla, Ribeiro, Servio, Silva, Israel F., Serrano, Artur R. M. (2014): Spatial distribution of Madeira Island Laurisilva endemic spiders (Arachnida: Araneae). Biodiversity Data Journal 2, 1051: 1051-1051, URL:http://dx.doi.org/10.3897/BDJ.2.e1051
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Biology

Steatoda nobilis, a species of comb-footed spider, characteristically hang upside down in webs known as tangle webs. Typically, their webs are built high off the ground in a darker corner.This group of spiders does not specialize on particular prey but are opportunistic and feed on almost any invertebrate that becomes entangled in their webs.

Size
Body length (excluding legs):
  • Female: 8–15mm
  • Male: 7–10mm
Size (including legs):
  • Female: 20–32mm
  • Male: 16–22mm


Lifecycle
In general, the life cycle lasts about one to two years and the females usually live longer than the smaller males.The white, spherical egg-sacs are produced at intervals, their number depending on the food supply. Eggs hatch within 2-4 months.

Life Expectancy
Males usually achieve maturity within a single year and die shortly after as they cease to feed once mature.Females achieve maturity within the second year and depending on environmental conditions and sufficient prey may live into the third year.

Reproduction
Mature and reproductive male spiders are found in summer and autumn, mature females can be found all year round and egg sacks are laid from spring through to autumn.

Dispersal
Local dispersal is achieved through ballooning on silk threads. Longer distance dispersal is aided by transportation of goods by road and rail and shipping network.
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Distribution

Distribution habitat

Distribution
Worldwide
  • Madeira
  • Canary Islands
  • Africa
  • mainland Europe
  • UK
UKThe false widow spider commonly occurs along a stretch of the south coast of England from Devon through to Dorset Sussex and more recently along to Essex. Steatoda nobilis is now spreading
  • quite rapidly south to London (Surrey) and Berkshire
    • while increasing in Essex
  • northwards with recent records from Leicestershire and Barry, South Glamorgan.
Steatoda nobilis has been established near the south coast of England for over a century with strongholds on the Dorset and Hampshire coast. The false widow spider is thought to be repeatedly introduced at ports with imports of bananas.

Habitat
Steatoda nobilis is strongly synanthropic and is most commonly found in and around domestic and commercial premises, including conservatories, public toilet blocks, garages and sheds.
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Conservation

Conservation Status

Conservation

Conservation status
The false widow spider is afforded no conservation status.

Threats
Due to its notoriety as the UK’s most venomous spider Steatoda nobilis may be threatened by remedial pest control.

Trends
Steatoda nobilis is currently a colonising species in the UK and has been expanding rapidly since the late 1980’s. The expansion of false widow spider is likely to be in response to increasing temperatures in the UK caused by climate change.

Risk Statement
Although this is a colonising species in the UK, it does occupy a somewhat vacant niche and is unlikely to have impact on other species of spider.
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Wikipedia

Steatoda nobilis

Steatoda nobilis is a spider in the genus Steatoda, known in the United Kingdom as the noble false widow[1][2] and often referred to as the false widow.[a] As the common name indicates, the spider superficially resembles and is frequently confused for the black widow and other spiders in the genus Latrodectus, which can have medically significant venom. Steatoda nobilis is native to Madeira and the Canary Islands from where it allegedly spread to Europe,[3] and arrived in England before 1879, perhaps through cargo sent to Torquay.[4] In England it has a reputation as one of the few local spider species which is capable of inflicting a painful bite to humans,[5] with most bites resulting in symptoms similar to a bee or wasp sting.[6]

Description[edit]

Steatoda nobilis has a brown bulbous abdomen with cream coloured markings that are often likened to the shape of a skull.[7] The legs are reddish-orange.[8] Females range in size from about 9.5 to 14 mm in size, while males are 7 to 11 mm.[1] Males are able to produce stridulation sounds during courtship, by scraping 10-12 teeth on the abdomen against a file on the rear of the carapace.

Male with swollen pedipalps

Distribution, habitat and ecology[edit]

The spider is an introduced species across Europe, plus parts of North Africa, and likely spreading. It was found for the first time in 2011 in Cologne, Germany.[9] It is originally from the Canary Islands and Madeira.[10] In England it has been reported mostly in southern counties,[11][12] but its range appears to be expanding northwards.[13][14] In 2011, the spider was reported as an established invasive species in the USA, in Ventura County, California.[15]

As with other members of the family Theridiidae, Steatoda nobilis constructs a cobweb which is an irregular tangle of sticky silken fibres. Its 'scaffold web' differs from others of the genus in the exceptional strength of the silk, and in the tubular retreat that is at least partly concealed in a deep crack or hole.[12] They have poor eyesight and depend mostly on vibrations reaching them through their webs to orient themselves to prey or warn them of larger animals that could injure or kill them.

Population expansion in UK and Ireland[edit]

Steatoda nobilis, Hampshire, England

The distribution of Steatoda nobilis is expected to increase northwards in the UK, due to, at least partly, mild winters in recent years. This prediction was reported by Stuart Hine of the Natural History Museum,[16] and is substantiated by the National Recording Scheme.[12]

The spider is reported to be an established species in Ireland.[17]

Medical significance[edit]

Female of Steatoda nobilis in Hampshire

Like almost all spiders, Steatoda nobilis is venomous, but its bite is almost exclusively of mild effect on humans, without the severe consequences that can occur with black widow spiders. Its bite is often alleged to be one of the medically significant for humans, even though the few recorded bites do not typically present long-lasting effects. The symptoms of a bite are typically similar to a bee or wasp sting.[8] The bite of this spider, along with others in the genus Steatoda, can produce a set of symptoms known as steatodism. Symptoms of bites include intense pain radiating from the bite site, along with feverishness or general malaise.[18]

Media reaction[edit]

Sensationalised stories about the bite of Steatoda nobilis have featured in UK newspaper articles.[19][20] Stuart Hine from the Natural History Museum, London responded on the naturenet blog, stating, "Of course I also explain the great value of spiders and how rare the event of spider bite in the UK actually is. I also always explain that up to 12 people die from wasp/bee stings in the UK each year and we do not panic so much about wasps and bees – but this never makes it past editing." [16] Steven Falk, an entomologist, cautioned that without "hard evidence", it is difficult to know how many of the bites reported in the media have been caused by false widow spiders.[21]

Alleged incidents[edit]

  • In 2006 a Dorchester man spent three days in Dorset County Hospital with symptoms of heart seizure, after suffering a spider bite believed to be caused by Steatoda nobilis.[5]
  • In 2012 a man collapsed in Southampton after apparently being bitten on his neck. He had complained of feeling hot, queasy and light headed. He required treatment in hospital, where it was discovered that he had been bitten 10 times on the neck, allegedly by the same large spider. The spider (which had been trapped in the victim's hooded jacket) was caught and tentatively identified by health workers as Steatoda nobilis.[22]
  • In 2012 a woman in Dorset suffered serious effects after her hand was supposedly bitten by a false widow spider.[23]
  • In 2013 a man in Sidcup of London was allegedly bitten in his sleep, reporting that his hand had turned black and yellow. His hand remained swollen for five weeks until doctors gave him a course of antibiotics.[24]
  • In October 2013, it was reported that a man from Romford in Essex had been allegedly bitten by a false widow. He was treated for bacterial infection with antibiotics and needed to have his leg drained of pus.[25]
  • In October 2013, a British school in the Forest of Dean was closed for a day for fumigation as a result of an outbreak of Steatoda nobilis on the site.[26]
  • In 2014, a woman from County Durham had her left index finger amputated after contracting the flesh-eating bug necrotising fasciitis following a spider bite claimed to be from a false widow spider.[27][28]
  • In October 2014, an Irish man went into cardiac arrest and spent a day in intensive care after being bitten three times by a false widow, on the hip, side and shoulder.[29]

Notes[edit]

a. ^ The correct and full English name for Steatoda nobilis is "Noble false widow". Media coverage usually abbreviates this to "false widow", although Steatoda nobilis is strictly speaking one of the false widows. Steatoda grossa[30] and Steatoda paykulliana[31] are other examples of false widow spiders.

References[edit]

  1. ^ a b Snazell, R. and Jones, D. (1993). "The theridiid spider Steatoda nobilis (Thorell, 1875) in Britain". Bulletin British Arachnological Society 9 (5): 164–167. 
  2. ^ Jones, D. (1993). "The Return of Steatoda nobilis (Thorell)". Newsletter of the British Arachnological Society 49: 7–8. 
  3. ^ Kulczycki, A., Legittimo, C.M., Simeon, E. and Di Pompeo, P. (2012). "New records of Steatoda nobilis (Thorell, 1875) (Araneae, Theridiidae), an introduced species on the Italian mainland and in Sardinia". Bulletin British Arachnological Society 15 (8): 269–272. doi:10.13156/arac.2012.15.1.269. 
  4. ^ Octavius Pickard-Cambridge (1879). "On some new and rare British spiders, with characters of a new genus". Annals and Magazine of Natural History 5 (4): 109–215. 
  5. ^ a b David Sapsted (17 November 2006). "Watch out, the black widow's sister is ready to bite you". Daily Telegraph (London). 
  6. ^ "False widow spider, Steatoda nobilis". Natural History Museum. Retrieved 11 October 2013. 
  7. ^ Sebastian Salek (24 September 2013). "More sightings of the false widow spider, as Britain's 'most venomous arachnid', with orange legs and white skull markings spotted in Essex". The Independent (London). 
  8. ^ a b "Noble false widow spider marches north in the UK". Natural History Museum. Retrieved 11 October 2013. 
  9. ^ "Observation by C Wieczorrek". 15 December 2006. Retrieved 22 November 2012. 
  10. ^ "World Distribution Map of S. Nobilis". British Arachnological Society. Sep–Oct 2012. Retrieved 22 Nov 2012. 
  11. ^ Harvey, P.R., Nellist, D.R. and M.G. Telfer, ed. (2002). Provisional Atlas of British spiders (Arachnida, Araneae) 1 &2. Huntingdon: Biological Records Centre. 
  12. ^ a b c "Summary for Steatoda nobilis (Araneae)". British Arachnological Society: National Recording Scheme. 2010–2012. Retrieved 22 Nov 2012. 
  13. ^ "Biting spider widens its web". BBC News. 2001-09-21. 
  14. ^ "Warning over rise in UK's most dangerous spider due to warmer winters". London: MailOnline. 2 May 2007. 
  15. ^ "European Spider, Steatoda nobilis Theridiidae". University of California, Riverside. Retrieved 11 October 2013. 
  16. ^ a b "The Ranger's Blog: The truth about Steatoda nobilis - is it the UK's most dangerous spider?". 2 May 2007. Retrieved 22 November 2012. 
  17. ^ "Poisonous false widow spiders spread across Ireland". Irish Independent. 18 October 2013. Retrieved 18 October 2013. 
  18. ^ Warrell, D.A., Shaheen, J., Hillyard, P. D. & D. Jones (1991). "Neurotoxic envenoming by an immigrant spider (Steatoda nobilis) in southern England". Toxicon 29 (10): 1263–1265. doi:10.1016/0041-0101(91)90198-Z. PMID 1801319. 
  19. ^ Williams, Rob (17 October 2013). "Killer spiders on the loose! (or not really) - a guide to the really quite harmless false widow". The Independent (London). Retrieved 17 October 2013. 
  20. ^ "False widow spiders aren't out to get us – and their bite isn't dangerous". The Guardian. 17 October 2013. Retrieved 17 October 2013. 
  21. ^ "False widow spider bites footballer Steve Harris". BBC News. 10 October 2013. Retrieved 10 October 2013. 
  22. ^ "Father collapses after being bitten 10 times by the UK's most venomous spider after it falls into his HOOD". Daily Mail (London). 20 February 2012. 
  23. ^ Luke Salkeld (18 April 2012). "'I nearly lost my hand to Britain's most poisonous spider': Woman bitten while she SLEPT by close relative of deadly Black Widow that lives in UK". Daily Mail (London). Retrieved 22 November 2012. 
  24. ^ Salek, Sebastian (19 September 2013). "Bites reported across London and Kent as south east sees influx of Britain's most poisonous spider". The Independent. Retrieved 4 October 2013. 
  25. ^ "Collier Row dad faced losing leg after false widow spider bite". Romford Recorder. 11 October 2013. 
  26. ^ "False widow spider outbreak shuts Forest of Dean school". BBC News. 22 October 2013. 
  27. ^ "Woman ‘loses finger after being bitten by a spider’". Sunderland Echo. 29 September 2014. 
  28. ^ "County Durham mum loses finger after spider bite causes flesh-eating bug". ChronicleLive. 29 September 2014. 
  29. ^ "A young father-of-one has told how he almost died when he was attacked and bitten by a lethal false widow spider". Irish Independent. 1 October 2014. 
  30. ^ The truth about false widow spiders Natural History Museum.
  31. ^ False widow spider, Steatoda paykulliana Natural History Museum.
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