The Chilean recluse spider is a venomous spider, Loxosceles laeta, of the family Sicariidae (formerly of the family Loxoscelidae). In Spanish, it (and other South American recluse spiders) is known as araña de rincón, or "spider of the corner"; in Portuguese, as Aranha-marrom or "brown spider". This spider is considered by many to be the most dangerous of the recluse spiders, and its bite is known to frequently result in severe systemic reactions, including death. Scientific classification or biological classification is a method by which biologists group and categorize species of organisms. ... “Animalia” redirects here. ... Subphyla and Classes Subphylum Trilobitomorpha Trilobita - trilobites (extinct) Subphylum Chelicerata Arachnida - spiders,scorpions, etc. ... Extant orders Acarina Amblypygi Araneae Opiliones Palpigradi Pseudoscorpionida Ricinulei Schizomida Solifugae Uropygi Wikispecies has information related to: Arachnida Arachnids are a class (Arachnida) of joint-legged invertebrate animals in the subphylum Chelicerata. ... Diversity 111 families, 40,000 species Suborders Mesothelae Mygalomorphae Araneomorphae  See table of families Closeup image of a Wolf Spider Wikispecies has information related to: Spiders Spiders are predatory invertebrate animals that have two body segments, eight legs, no chewing mouth parts and no wings. ... Sicariidae are members of a genus of spiders found in arid portions of South America and southern Africa. ... This page is a candidate for speedy deletion. ... In biology, binomial nomenclature is the formal system of naming species. ... Diversity 111 families, 40,000 species Suborders Mesothelae Mygalomorphae Araneomorphae  See table of families Closeup image of a Wolf Spider Wikispecies has information related to: Spiders Spiders are predatory invertebrate animals that have two body segments, eight legs, no chewing mouth parts and no wings. ... This page is a candidate for speedy deletion. ... Sicariidae are members of a genus of spiders found in arid portions of South America and southern Africa. ... Genera Loxosceles Sicarius The recluse spiders (family Sicariidae) comprise two genera and 122 species [1], best known being the Brown recluse spider. ...

Description and habitat

The Chilean recluse is one of the larger species of recluse spiders, generally ranging from 8-30 mm in size (including legs). Like most recluses, it is brown and usually has markings on the dorsal side of its thorax, with a black line coming from it that looks like a violin with the neck of the violin pointing to the rear of the spider resulting in the nickname "fiddleback spider" or "violin spider" in English-speaking areas. Coloring varies from light tan to brown and the violin marking may not be visible. Since the "violin pattern" is not diagnostic, it is far more important, for purposes of identification, to examine the eyes. Contrary to most spiders, which have 8 eyes, recluse spiders have 6 eyes arranged in pairs (dyads) with one median pair and 2 lateral pairs. In anatomy, the dorsum is the upper or back side of an animal, as opposed to the ventrum. ... Diagram of a tsetse fly, showing the head, thorax and abdomen The thorax is a division of an animals body that lies between the head and the abdomen. ... The violin is a bowed string instrument with four strings tuned in perfect fifths. ... The English language is a West Germanic language that originates in England. ... Etymology: Late Latin dyad-, dyas, from Greek, from dyo The word dyad has a number of uses: A dyad (general) pair, consisting of two parts. ... In probability theory and statistics, a median is a number dividing the higher half of a sample, a population, or a probability distribution from the lower half. ... The term lateral can refer to: an anatomical definition of direction. ...

The Chilean recluse spider is native to South America (it is common Chile, but is found throughout South America), but is found in many places worldwide, including the North and Central America, Finland, and Australia. The spider is known to have established itself in the Los Angeles area, and infestations have been reported in Vancouver, British Columbia, Cambridge, Massachusetts, and Florida.^[1][2] South America South America is a continent crossed by the equator, with most of its area in the Southern Hemisphere. ... North America North America is a continent [1] in the Earths northern hemisphere and (chiefly) western hemisphere. ... For other uses, see Central America (disambiguation). ... Flag Seal Nickname: City of Angels Location Location within Los Angeles County in the state of California Coordinates , Government State County California Los Angeles County Mayor Antonio Villaraigosa (D) Geographical characteristics Area     City 1,290. ... This article refers to the city in British Columbia, Canada. ... Location in Massachusetts Coordinates: , Country United States State Massachusetts County Middlesex County Settled 1630 Incorporated 1636 Government  - Type Mayor-council city  - Mayor Kenneth Reeves (D) Area  - City  7. ... Official language(s) English Capital Tallahassee Largest city Jacksonville Largest metro area Miami Area  Ranked 22nd  - Total 65,795[1] sq mi (170,304[1] km²)  - Width 361 miles (582 km)  - Length 447 miles (721 km)  - % water 17. ...

Like other recluse spiders, the Chilean recluse build irregular webs that frequently include a shelter consisting of disorderly threads. Unlike most web weavers, they leave these webs at night to hunt. People get bitten when they unintentionally squeeze them in clothing and bedding. These spiders frequently build their webs in woodpiles and sheds, closets, garages, and other places that are dry and generally undisturbed. The spider frequently is found in dwellings, in parts of its range where humans are found. The spiders can last a long time without food or water ^[3], a fact which encourages their worldwide distribution.

Medical significance

As indicated by its name, this spider is not aggressive and usually bites only when pressed against human skin, such as when putting on an article of clothing. Like all Sicariidae spiders, the venom of the Chilean recluse contains the dermonecrotic agent, sphingomyelinase D, which is otherwise found only in a few pathogenic bacteria. According to one study, the venom of the Chilean recluse (along with the six-eyed sand spider), contains an order of magnitude more of this substance than do other Sicariidae spiders such as the brown recluse^[4]. Binomial name Sicarius hahnii Walckenaer, 1847 The six-eyed sand spider (Sicarius hahnii) is a medium-sized spider of deserts and other sandy places in southern Africa. ... A brown recluse spider The brown recluse spider is a venomous spider of the family Sicariidae and the genus and species Loxosceles reclusa. ...

Some bites are minor with no necrosis, but a small number produce severe dermonecrotic lesions (cutaneous loxoscelism) or even systemic conditions (viscerocutaneous loxoscelism); sometimes resulting in renal failure and in 3-4% of cases in a recent clinincal study in Chile, death. ^[5] (For a comparison of the toxicity of several kinds of spider bites, see the list of spiders having medically significant venom.) Necrosis (in Greek Νεκρός = Death) is the name given to accidental death of cells and living tissue. ... Renal failure is the condition in which the kidneys fail to function properly. ... Spiders having medically significant venom exist in almost all parts of the world except those that are coldest. ...

The serious bites form a necrotising ulcer that destroys soft tissue and may take months and very rarely years to heal, leaving deep scars. The damaged tissue will become gangrenous and eventually slough away. Initially there may be no pain from a bite, but over time the wound may grow to as large as 10 inches (25 cm) in extreme cases. Bites may take up to seven hours to cause visible damage; more serious systemic effects may occur before this time, as venom of any kind spreads throughout the body in minutes. Deaths have been reported for the related South American species L. intermedia. A longstanding medical condition known by travellers and residents to Chile, the gangrenous spot of Chile, is now believed to be caused by recluse spider bites. Endoscopic images of a duodenal ulcer. ... This article or section does not adequately cite its references or sources. ... Gangrene is necrosis and subsequent decay of body tissues caused by infection or thrombosis or lack of blood flow. ...

First aid involves the application of an ice pack to control inflammation, the application of aloe vera to soothe and help control the pain, and prompt medical care. If it can be easily captured, the spider should be brought with the patient in a clear, tightly closed container so it may be identified. However, by the time the bite is noticed any spider found nearby is not likely to be the culprit. An abscess on the skin, showing the redness and swelling characteristic of inflammation. ...

Notes

1. ^ Gertsch WJ. The spider genus Loxosceles in South America (Araneae: Scytodidae). Bulletin of American Museum of Natural History 136:119-183, 1967.
2. ^ Gertsch WJ, Ennik F. The spider genus Loxosceles in North America, Central America, and the West Indies (Araneae, Loxoscelidae). Bulletin of American Museum of Natural History 175: 264-360, 1983.
3. ^ Lowrie DC. Starvation longevity of Loxosceles laeta (Nicolet) (Araneae). Entomology News 91: 130-132, 1980.
4. ^ http://www.lclark.edu/~binford/SMDDistribution%20copy.pdf Greta J. Binford abd Michael A. Wells, "The phylogenetic distribution of sphingomyelinase D activity in venoms of Haplogyne spiders", Comparative Biochemistry and Physiology Part B 135 (2003) 25–33
5. ^ http://bases.bireme.br/cgi-bin/wxislind.exe/iah/online/?IsisScript=iah/iah.xis&nextAction=lnk&base=MEDLINE_1966-1995&exprSearch=2577020&indexSearch=UI&lang=i Schenone H, Saavedra T, Rojas A, Villarroel F. "Loxoscelism in Chile. Epidemiologic, clinical and experimental studies". Revista do Instituto de Medicina Tropical de São Paulo 31:403-415, 1989

External links

• A clinical and epidemiological study of Loxosceles spider envenoming in Santa Catarina, Brazil. Trans R Soc Trop Med Hyg. 1998 Sep-Oct;92(5):546-8.
• Brown Recluse Spider Bites
• Alejandro Palma, "Loxoscelismo" Universidad de Concepción (in Spanish, contains graphic images)