Latrodectus geometricus

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Latrodectus geometricus
Brown widow spider Latrodectus geometricus low oblique view.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Chelicerata
Class: Arachnida
Order: Araneae
Infraorder: Araneomorphae
Family: Theridiidae
Genus: Latrodectus
Species:
L. geometricus
Binomial name
Latrodectus geometricus
Koch, 1841 [1]
Synonyms [1]
  • Theridium zickzackKarsch, 1878
  • Latrodectus concinnusO. Pickard-Cambridge, 1904
  • Chacoca distinctaBadcock, 1932

Latrodectus geometricus, commonly known as the brown widow, [2] [3] brown button spider, grey widow, brown black widow, [3] 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.

Contents

Orange hourglass marking on the belly of a brown widow Brown widow spider Latrodectus geometricus underside.jpg
Orange hourglass marking on the belly of a brown widow
A brown widow's egg sac Latrodectus RUSVM egg sac.jpg
A brown widow's egg sac
Brown widow spider found in Cairo, Egypt 20140627 001020CLOSE.jpg
Brown widow spider found in Cairo, Egypt

Taxonomy

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.

Description

L. geometricus is slightly smaller [4] 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, [4] and they are sometimes described as "tufted", "fluffy", [4] or "spiky" in appearance. Eggs hatch in approximately 20 days. [5] Female brown widows lay about 120–150 eggs per sac and can make 20 egg sacs over a lifetime. [2]

Predators

Because L. geometricus is dispersed all around the globe, they have many predators. Brown widows are commonly preyed upon by different types of wasps, including mud daubers and digger wasps.

Geographic distribution

The brown widow has a cosmopolitan distribution. [1] 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. [1] It is thought by some researchers to originate in South Africa, [3] although this is uncertain, as specimens were discovered in both Africa and South America. [2] They are usually found around buildings in tropical areas. They can compete with populations of the black widow spider. [6] It is found in many areas of South Africa, the United States (including Hawaii), [2] [3] [4] Australia, [2] Japan, [7] the Dominican Republic, [8] and Cyprus. [2]

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. [9] [10] 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. [10]

Toxicology

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. [6] The effects of the toxin are usually confined to the bite area and surrounding tissue, unlike the black widow's. [4] 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. [2] The LD 50 of L. geometricus venom has been measured in mice as 0.43 mg/kg, [11] and separately again as 0.43 mg/kg (with a 95% confidence interval of 0.31–0.53). [12]

Related Research Articles

<i>Latrodectus mactans</i> Species of spider

Latrodectus mactans, known as southern black widow or simply black widow, and the shoe-button spider, is a venomous species of spider in the genus Latrodectus. The females are well known for their distinctive black and red coloring and for the fact that they will occasionally eat their mates after reproduction. The species is native to North America. The venom can cause pain and other symptoms, but is rarely fatal to healthy humans.

<i>Latrodectus</i> Genus of spiders

Latrodectus is a broadly distributed genus of spiders with several species that are commonly known as the true widows. This group is composed of those often loosely called black widow spiders, brown widow spiders, and similar spiders. However, the diversity of species is much greater. A member of the family Theridiidae, this genus contains 34 species, which include several North American "black widows". Besides these, North America also has the red widow Latrodectus bishopi and the brown widow Latrodectus geometricus, which, in addition to North America, has a much wider geographic distribution. Elsewhere, others include the European black widow, the Australian redback spider and the closely related New Zealand katipō, several different species in Southern Africa that can be called button spiders, and the South American black-widow spiders. Species vary widely in size. In most cases, the females are dark-coloured and can be readily identified by reddish markings on the central underside (ventral) abdomen, which are often hourglass-shaped.

<span class="mw-page-title-main">Pholcidae</span> Family of spiders

The Pholcidae are a family of araneomorph spiders. The family contains more than 1,800 individual species of pholcids, including those commonly known as cellar spider, daddy long-legs spider, carpenter spider, daddy long-legger, vibrating spider, gyrating spider, long daddy, and skull spider. The family, first described by Carl Ludwig Koch in 1850, is divided into 94 genera.

<span class="mw-page-title-main">Redback spider</span> Species of spider

The redback spider, also known as the Australian black widow, is a species of highly venomous spider believed to originate in South Australia or adjacent Western Australian deserts, but now found throughout Australia, Southeast Asia and New Zealand, with colonies elsewhere outside Australia. It is a member of the cosmopolitan genus Latrodectus, the widow spiders. The adult female is easily recognised by her spherical black body with a prominent red stripe on the upper side of her abdomen and an hourglass-shaped red/orange streak on the underside. Females usually have a body length of about 10 millimetres (0.4 in), while the male is much smaller, being only 3–4 mm (0.12–0.16 in) long.

<i>Latrodectus bishopi</i> Species of spider

Latrodectus bishopi is the scientific name for the red widow spider, which is endemic to certain habitats of central and southern Florida, where it lives primarily in sand dunes dominated by sand pine, Pinus clausa – a type of vegetation found only in peninsular Florida.

<span class="mw-page-title-main">Katipō</span> Species of arachnid native to New Zealand

The katipō is an endangered species of spider native to New Zealand. It is one of many species in the genus Latrodectus, such as the Australian redback, and the North American black widow. The species is venomous to humans, capable of delivering a potentially dangerous bite. It is a small to medium-sized spider, with the female having a round black or brown pea-sized body. Red katipō females found in the South Island and the lower half of the North Island, are always black, and their abdomen has a distinctive red stripe bordered in white. In black katipō females found in the upper half of the North Island, this stripe is absent, pale, yellow, or replaced with cream-coloured blotches. These two forms were previously thought to be separate species. The male is much smaller than the female and quite different in appearance: white with black stripes and red diamond-shaped markings. Katipō are mainly found living in sand dunes close to the seashore. They are found throughout most of coastal New Zealand except the far south and west. Katipō feed mainly on ground dwelling insects, caught in an irregular tangled web spun amongst dune plants or other debris.

<i>Heteropoda venatoria</i> Species of spider

Heteropoda venatoria is a species of spider in the family Sparassidae, the huntsman spiders. It is native to the tropical regions of the world, and it is present in some subtropical areas as an introduced species. Its common names include giant crab spider, banana huntsman spider or cane spider.

Button spider is a common name used in Southern Africa to refer to local members of the spider genus, Latrodectus, the family Theridiidae. There are both black and brown button spiders in Southern Africa, that are known elsewhere as widow spiders. Seven Latrodectus species can be found in Southern Africa; six of them are native, one is possibly imported.

<i>Latrodectus tredecimguttatus</i> Species of spider

Latrodectus tredecimguttatus, also known as the Mediterranean black widow, or the European black widow, is a species in the genus Latrodectus of the widow spiders. It is commonly found throughout the Mediterranean region, ranging from southern Iberia to southwest and central Asia, hence the name. Specimens from central Asia are also known by the binomial name Latrodectus lugubris; that name, however, is now considered improper, though it is still commonly found in the literature. Latrodectus tredecimguttatus was previously considered a subspecies of Latrodectus mactans.

<i>Steatoda</i> Genus of spiders

The spider genus Steatoda, in the family Theridiidae, includes about 120 recognized species, distributed around the world. One common name is cupboard spider, for many species build their webs in dark, sheltered, undisturbed places around the house or garden, in sheds and garages, under garden furniture, compost bins, and the like. Signs of the cupboard spider include small white spots of spider droppings, like small splashes of paint, on the floor underneath the web.

<span class="mw-page-title-main">Spider bite</span> Bite caused by a spider

A spider bite, also known as arachnidism, is an injury resulting from the bite of a spider. The effects of most bites are not serious. Most bites result in mild symptoms around the area of the bite. Rarely they may produce a necrotic skin wound or severe pain.

<i>Steatoda grossa</i> Species of spider

Steatoda grossa, commonly known as the cupboard spider, the dark comb-footed spider, the brown house spider, or the false widow or false black widow, is a common species of spider in the genus Steatoda.

<i>Latrodectus pallidus</i> Species of spider

Latrodectus pallidus is a species of spider commonly found throughout North Africa, the Middle East, and central Asia. A common name in English is the white widow spider, and it is known in Russian as белый каракурт, or white steppe spider. It is a member of the genus Latrodectus, which includes species known as widow spiders, which is placed in the family Theridiidae. It occurs both in the steppes of southern Russia, Kazakhstan, and other southwest Asian countries, as well as in the desert regions of the Middle East. Compared to other widow spiders in the region, the white widow spider is comparatively rare.

<i>Latrodectus variolus</i> Species of spider

Latrodectus variolus, the northern black widow spider or northern widow, is a venomous species of spider in the genus Latrodectus of the family Theridiidae. The population is closely related to the southern black widow, Latrodectus mactans, and the western black widow, Latrodectus hesperus, of the genus.

<i>Latrodectus hesperus</i> Species of spider

Latrodectus hesperus, the western black widow spider or western widow, is a venomous spider species found in western regions of North America. The female's body is 14–16 mm in length and is black, often with an hourglass-shaped red mark on the lower abdomen. This "hourglass" mark can be yellow, and on rare occasions, white. The male of the species is around half this length and generally a tan color with lighter striping on the abdomen. The population was previously described as a subspecies of Latrodectus mactans and it is closely related to the northern species Latrodectus variolus. The species, as with others of the genus, build irregular or "messy" webs: unlike the spiral webs or the tunnel-shaped webs of other spiders, the strands of a Latrodectus web have no apparent organization.

<i>Steatoda nobilis</i> Species of spider

Steatoda nobilis is a spider in the genus Steatoda, known in the United Kingdom as the noble false widow, as it superficially resembles and is frequently mistaken for the black widow and other spiders in the genus Latrodectus. It is often referred to as thefalse widow, although "false widow" is a more general term applied to a wider group of species with this resemblance. It is a moderately medically significant spider, with most bites resulting in symptoms similar to a bee or wasp sting. Some bites may cause more significant harm, partly due to pathogenic bacteria from the spiders.

<i>Latrodectus indistinctus</i> Species of spider

Latrodectus indistinctus is a species of spider in the family Theridiidae, found in Namibia and South Africa. It is one of six species of Latrodectus found in southern Africa, four of which, including L. indistinctus, are known as black button or black widow spiders. Like all Latrodectus species, L. indistinctus has a neurotoxic venom. It acts on nerve endings, causing the very unpleasant symptoms of latrodectism when humans are bitten.

<span class="mw-page-title-main">Latrodectism</span> Medical condition

Latrodectism is the illness caused by the bite of Latrodectus spiders. Pain, muscle rigidity, vomiting, and sweating are the symptoms of latrodectism.

<i>Latrodectus curacaviensis</i> Species of spider

Latrodectus curacaviensis is a species of black widow spider, that belongs to the genus Latrodectus. It is known as the South American black widow, Brazilian black widow or Araña del trigo.

References

  1. 1 2 3 4 "Taxon details Latrodectus geometricus C.L. Koch, 1841". World Spider Catalog. Natural History Museum Bern. Retrieved 29 October 2016.
  2. 1 2 3 4 5 6 7 Vetter, Richard S. (2013). "The brown widow spider, Latrodectus geometricus". Department of Entomology, Center for Invasive Species Research, University of California, Riverside . Retrieved 15 July 2013.
  3. 1 2 3 4 Reagan, Mark (12 August 2011). "It's officially confirmed: There's a new spider in southwest Kansas". Dodge City Daily Globe . Archived from the original on 25 March 2012. Retrieved 28 September 2012.
  4. 1 2 3 4 5 Santana, Fred (2007). "Brown Widow Spiders". Sarasota County, Florida: Institute of Food and Agricultural Sciences, University of Florida. Retrieved 28 September 2012.
  5. ↑ Jackman, J A (2006). "Spiders Archived 22 August 2007 at the Wayback Machine ", Texas Agricultural Extension Service.
  6. 1 2 Brown, Eryn (2 July 2012). "Brown widow spiders 'taking over' in Southern California". Los Angeles Times . Retrieved 28 September 2012.
  7. ↑ Ono, H (1995). "Records of Latrodectus geometricus (Araneae: Theridiidae) from Japan". Acta Arachnologica. 44 (2): 167–170. doi: 10.2476/asjaa.44.167 .
  8. ↑ "Hallan araña Viuda Marrón en Salinas de Baní" (in Spanish). El Nacional. 24 January 2012. Retrieved 8 October 2012.
  9. ↑ Are Brown Widow Spiders Displacing Black Widows? http://www.entsoc.org/press-releases/are-brown-widow-spiders-displacing-black-widows
  10. 1 2 Vetter, Richard S.; Vincent, Leonard S.; Danielsen, Douglas W.R.; Reinker, Kathryn I.; Clarke, Daniel E. (July 2012). "The Prevalence of Brown Widow And Black Widow Spiders in Urban Southern California". Journal of Medical Entomology. 49 (4): 947–51. doi: 10.1603/me11285 . PMID   22897057.
  11. ↑ Rauber, Albert (1 January 1983). "Black Widow Spider Bites". Clinical Toxicology. 21 (4–5): 473–485. doi:10.3109/15563658308990435. PMID   6381753.
  12. ↑ McCrone, J.D. (1 December 1964). "Comparative lethality of several Latrodectus venoms". Toxicon. 2 (3): 201–203. doi:10.1016/0041-0101(64)90023-6. PMID   14298228.
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