{{Short description|Species of spider}} {{Use dmy dates|date=November 2020}} {{Speciesbox | name = | image = Brown widow spider Latrodectus geometricus low oblique view.jpg | image_caption = | image2 = Latrodectus geometricus 305447352 550735821.jpg | image2_caption = Female from South Africa | taxon = Latrodectus geometricus | authority = Koch, 1841<ref name="koch1841" /> | synonyms = {{Species list |Theridium zickzack|Karsch, 1878 |Theridion zickzack|O. Pickard-Cambridge, 1904 |Latrodectus concinnus|O. Pickard-Cambridge, 1904 |Chacoca distincta|Badcock, 1932 |Latrodectus distinctus|Levy & Amitai, 1983 |Latrodectus geometoricus|Yoshida, 2003 }} | synonyms_ref = <ref name=wsc /> }}
'''''Latrodectus geometricus''''', commonly known as the '''brown widow''',<ref name="Vetter CISR 2012" /><ref name="dodge" /> '''brown button spider''', '''grey widow''', '''brown black widow''',<ref name=dodge /> '''house button spider''' or '''geometric button spider''', is one of the widow spiders in the genus ''Latrodectus''. As such, it is a 'cousin' to the more infamous ''Latrodectus mactans'' (black widow).
''L. geometricus'' has black and white patterns on the sides of its abdomen as well as an orange-yellow colored hourglass shape marking. Their eggs are easily identified by points that project from all over the egg sacs. ''L. geometricus'' are found all over the world, but are believed to originate in Africa or South America. Their bites, though painful, are not considered to be dangerous.
==Habitat and ecology== <gallery mode=packed heights=160px> Latrodectus geometricus 300943521 542268330.jpg|female with egg sac Latrodectus geometricus 300943521 542268842.jpg| Latrodectus geometricus 305447352 550735451.jpg|dark female </gallery> This species constructs three-dimensional webs in dark corners in a variety of microhabitats and is commonly found around houses. The egg sac is distinctive with spikes.<ref name="dippenaar2021" />
''L. geometricus'' builds webs with a retreat from which delaying retreats radiate. From the delaying threads to the ground, sticky threads are laid down. The retreat has either one or two openings, with the main one opening onto the delaying threads. Webs are built at varying heights above the ground in vegetation and around buildings.<ref name="dippenaar2021" />
In South Africa, ''Latrodectus geometricus'' inhabits a large range at altitudes from 0 to 1941 m above sea level. It has been sampled from all floral biomes in South Africa and is commonly found in crops including avocado, citrus, cotton, maize, pistachio, prickly pears, and vineyards.<ref name="dippenaar2021" />
== Geographic distribution == The brown widow has a cosmopolitan distribution.<ref name=wsc /> The World Spider Catalog gives its native distribution as Africa, with introductions to the Americas, Poland, the Middle East, Pakistan, India, Thailand, Japan, China, Papua New Guinea, Australia and Hawaii.<ref name=wsc /> It is thought by some researchers to originate in South Africa,<ref name=dodge /> although this is uncertain, as specimens were discovered in both Africa and South America.<ref name="Vetter CISR 2012" /> They are usually found around buildings in tropical areas. They can compete with populations of the black widow spider.<ref name="taking over" /> It is found in many areas of South Africa, the United States (including Hawaii),<ref name="Vetter CISR 2012" /><ref name="dodge" /><ref name=Santana /> Australia,<ref name="Vetter CISR 2012" /> Japan,<ref name="fix2" /> the Dominican Republic,<ref name="fix3" /> Costa Rica,<ref name="fix4" /> and Cyprus.<ref name="Vetter CISR 2012" />
=== Threat to native species === As of 2012, researchers at the University of California, Riverside, suggested that the brown widow spider, newly established in Southern California, may in fact be displacing black widow spiders from the region, competing and/or fighting for territory.<ref name="fix5" /><ref name=california /> While certainly not definitive, this evidence does suggest that the brown widow is likely to be more hostile and aggressive towards its relative, the black widow, than the black widow is towards it. If that proves to be true, humans may be positively affected since brown widow bites are less toxic than those of black widows, thus posing less of a threat as they displace black widows over time.<ref name=california />
== Description == <gallery mode=packed heights=160px> Brown widow spider Latrodectus geometricus underside.jpg|Orange hourglass marking Latrodectus RUSVM egg sac.jpg|egg sac 20140627 001020CLOSE.jpg|Cairo, Egypt ViudaCafé_variación_oscura.png|dark color variation Costa Rica </gallery>
''L. geometricus'' is slightly smaller<ref name=Santana /> and generally lighter in color than the black widow species; the color can range from tan to dark brown to black, with shades of grey also possible. Like the black widow species in the United States, ''L. geometricus'' has a prominent hourglass-shaped marking on the underside of the abdomen; the brown widow's hourglass, however, is usually a vivid orange or a yellowish color. Unlike the black widow, ''L. geometricus'' has a black-and-white geometric pattern on the dorsal side of its abdomen. They also have stripes on their legs.
Brown widows can be located by finding their egg sacs, which are easily identifiable. They resemble a sandspur, having pointed projections all over,<ref name=Santana /> and they are sometimes described as "tufted", "fluffy",<ref name=Santana /> or "spiky" in appearance. Eggs hatch in approximately 20 days.<ref name="fix1" /> Female brown widows lay about 120–150 eggs per sac and can make 20 egg sacs over a lifetime.<ref name="Vetter CISR 2012" />
== Taxonomy == {{Unreferenced section|date=May 2026}} ''L. geometricus'' derives its name from the geometric patterning on its abdomen. However, the spider's coloring can and does darken over time and the pattern may become obscured.
Similar widows include the ''L. rhodesiensis'', a brown-colored relative of ''L. geometricus'' which is native to Zimbabwe. Both species are collectively known as brown button spiders throughout southern Africa.
== Predators == Because ''L. geometricus'' is dispersed all around the globe, they have many predators.{{citation needed|date=May 2026}} Brown widows are commonly preyed upon by different types of wasps, including blue mud-dauber wasps<ref name=Nel2014/> and digger wasps.{{citation needed|date=May 2026}}
==Toxicology== {{Main|Latrodectism}}
Like all ''Latrodectus'' species, ''L. geometricus'' has a neurotoxic venom. The venom acts on nerve endings causing the very unpleasant symptoms of latrodectism. However, brown widow bites are usually not very dangerous; usually much less dangerous than those of ''L. mactans'', the black widow.<ref name="taking over" /> The effects of the toxin are usually confined to the bite area and surrounding tissue, unlike the black widow's.<ref name=Santana /> Mere toxicity of the venom is not the only factor in dangerousness. Brown widow bites are minor compared to black widow bites because they cannot deliver the same amount of venom as the black widow.<ref name="Vetter CISR 2012" /> The LD<sub>50</sub> of ''L. geometricus'' venom has been measured in mice as 0.43 mg/kg,<ref name="fix6" /><ref name="fix7" />
==Conservation== ''Latrodectus geometricus'' is listed as Least Concern by the South African National Biodiversity Institute due to its wide geographical range. The species is well protected in more than ten reserves and parks.<ref name="dippenaar2021" />
==Taxonomy== The genus was revised by Lotz in 1994.<ref name="lotz1994" />
== References == {{Reflist|refs= <ref name="wsc">{{cite web | url=https://wsc.nmbe.ch/species/39047 | title=Latrodectus geometricus C. L. Koch, 1841 | publisher=World Spider Catalog | accessdate=2025-10-01}}</ref>
<ref name="california">{{Cite journal |last1=Vetter |first1=Richard S. |last2=Vincent |first2=Leonard S. |last3=Danielsen |first3=Douglas W.R. |last4=Reinker |first4=Kathryn I. |last5=Clarke |first5=Daniel E. |date=July 2012 |title=The Prevalence of Brown Widow And Black Widow Spiders in Urban Southern California |pmid=22897057 |journal=Journal of Medical Entomology |doi=10.1603/me11285 |volume=49 |issue=4 |pages=947–51|doi-access=free }}</ref>
<ref name="dippenaar2021">{{cite book | last1=Dippenaar-Schoeman | first1=A.S. | last2=Haddad | first2=C.R. | last3=Foord | first3=S.H. | last4=Lotz | first4=L.N. | year=2021 | title=The Theridiidae of South Africa. Part 1 A-P | publisher=South African National Survey of Arachnida Photo Identification Guide | pages=39-41 | doi=10.5281/zenodo.7515890}}{{Creative Commons text attribution notice|cc=by4}}</ref>
<ref name="dodge">{{cite news|title=It's officially confirmed: There's a new spider in southwest Kansas |url=http://www.dodgeglobe.com/news/x386655782/Its-officially-confirmed-Theres-a-new-spider-in-southwest-Kansas |first=Mark |last=Reagan |newspaper=Dodge City Daily Globe |date=12 August 2011 |accessdate=28 September 2012 |url-status=dead |archiveurl=https://web.archive.org/web/20120325113522/http://www.dodgeglobe.com/news/x386655782/Its-officially-confirmed-Theres-a-new-spider-in-southwest-Kansas |archivedate=25 March 2012 }}</ref>
<ref name="fix1">Jackman, J A (2006). "[http://ward-co.tamu.edu/publications/spi.pdf Spiders] {{webarchive|url=https://web.archive.org/web/20070822052011/http://ward-co.tamu.edu/publications/spi.pdf |date=22 August 2007 }}", Texas Agricultural Extension Service.</ref> <ref name="fix2">{{cite journal | last= Ono | first= H | year= 1995 | title= Records of Latrodectus geometricus (Araneae: Theridiidae) from Japan | journal= Acta Arachnologica | volume= 44 | pages= 167–170 | issue= 2 | doi= 10.2476/asjaa.44.167 | doi-access= free }}</ref>
<ref name="fix3">{{cite web | url=http://elnacional.com.do/hallan-arana-viuda-marron-en-salinas-de-bani| title=Hallan araña Viuda Marrón en Salinas de Baní| language=Spanish |publisher=El Nacional | date= 24 January 2012 | accessdate= 8 October 2012}}</ref>
<ref name="fix4">{{cite journal | url=https://www.scielo.sa.cr/scielo.php?script=sci_arttext&pid=S0001-60022017000200073| title=Latrodectism in Costa Rica| journal=Acta Médica Costarricense| language=Spanish |publisher=SciCielo Costa Rica | date= June 2017 | volume=59| issue=2| pages=73–74| accessdate= 11 November 2024| last1=Barrantes-Montero| first1=Gilbert| last2=Valerio-Pizarro| first2=Raquel| last3=Barrantes-Montero| first3=Gilbert| last4=Valerio-Pizarro| first4=Raquel}}</ref>
<ref name="fix5">Are Brown Widow Spiders Displacing Black Widows? http://www.entsoc.org/press-releases/are-brown-widow-spiders-displacing-black-widows {{Webarchive|url=https://web.archive.org/web/20151222163557/http://www.entsoc.org/press-releases/are-brown-widow-spiders-displacing-black-widows |date=22 December 2015 }}</ref>
<ref name="fix6">{{cite journal|last=Rauber|first=Albert|title=Black Widow Spider Bites|journal=Clinical Toxicology|date=1 January 1983|volume=21|issue=4–5|pages=473–485|doi=10.3109/15563658308990435|pmid=6381753}}</ref>
<ref name="fix7">{{cite journal|last=McCrone|first=J.D.|title=Comparative lethality of several Latrodectus venoms|journal=Toxicon|date=1 December 1964|volume=2|issue=3|pages=201–203|doi=10.1016/0041-0101(64)90023-6|pmid=14298228|bibcode=1964Txcn....2..201M }}</ref>
<ref name="koch1841">{{cite book | last=Koch | first=C.L. | year=1841 | title=Die Arachniden. Achter Band | publisher=C. H. Zeh'sche Buchhandlung | location=Nürnberg | pages=41-131 | doi=10.5962/bhl.title.43744}}</ref>
<ref name="lotz1994">{{cite journal | last=Lotz | first=L.N. | year=1994 | title=Revision of the genus Latrodectus (Araneae: Theridiidae) in Africa | journal=Navorsinge van die Nasionale Museum Bloemfontein | volume=10 | pages=1-60}}</ref>
<ref name="Santana">{{cite web | url= http://sarasota.ifas.ufl.edu/IPM/BrownWidow.htm | title= Brown Widow Spiders | first= Fred | last= Santana | publisher= Institute of Food and Agricultural Sciences, University of Florida | location= Sarasota County, Florida | year= 2007 | accessdate= 28 September 2012 | archive-date= 18 January 2016 | archive-url= https://web.archive.org/web/20160118225911/http://sarasota.ifas.ufl.edu/IPM/BrownWidow.htm | url-status= dead }}</ref>
<ref name="taking over">{{cite news| url=https://www.latimes.com/science/la-xpm-2012-jul-02-la-sci-sn-brown-widow-spider-california-20120702-story.html | title= Brown widow spiders 'taking over' in Southern California | first= Eryn | last= Brown | work= Los Angeles Times | date= 2 July 2012 | access-date= 28 September 2012}}</ref>
<ref name="Vetter CISR 2012">{{cite web | url= http://cisr.ucr.edu/brown_widow_spider.html |title= The brown widow spider, ''Latrodectus geometricus'' | first= Richard S. | last= Vetter | publisher= Department of Entomology, Center for Invasive Species Research, University of California, Riverside | year=2013 | accessdate= 15 July 2013}}</ref>
<ref name=Nel2014>{{cite journal |last1=Nel |first1=Ernst |last2=Kelly |first2=Janine |last3=Dippenaar-Schoeman |first3=Anna |date=2014 |title=Notes on the biology of the wasp, ''Chalybion spinolae'' (Hymenoptera: Sphecidae), an obligatory predator of ''Latrodectus'' (Araneae: Theridiidae) spiders in South Africa |journal=Journal of Natural History |volume=48 |issue=25-26 |pages=1585-1593 |doi=10.1080/00222933.2013.877993|hdl=2263/58929 |hdl-access=free }}</ref> }}
== External links == * [https://archive.today/20121007171615/http://www3.interscience.wiley.com/journal/119400198/abstract Sexual Cannibalism in the Brown Widow Spider (''Latrodectus geometricus'')] * [http://cisr.ucr.edu/brown_widow_spider.html Brown Widow Spider at the Center for Invasive Species Research] * {{Cite web |title=Brown widow spider - Latrodectus geometricus |url=https://entnemdept.ufl.edu/creatures/URBAN/SPIDERS/brown_widow_spider.htm |access-date=2023-03-15 |website=entnemdept.ufl.edu |last1=Hall |first1=Donald W. |date=February 2016 |series=Featured Creatures |publisher=Entomology and Nematology Department, University of Florida}}
{{Taxonbar|from=Q82243}} {{Authority control}}
geometricus Category:Cosmopolitan spiders Category:Spiders described in 1841 Category:Taxa named by Carl Ludwig Koch