Recluse spider

Taxobox
name = Recluse spiders


image_width = 200px
image_caption = Loxosceles amazonica spider
regnum = Animalia
phylum = Arthropoda
classis = Arachnida
ordo = Araneae
familia = Sicariidae
genus = "Loxosceles"
genus_authority = Heineken & Lowe, 1832
diversity_link = List of Sicariidae species#Loxosceles
diversity = 100 species
subdivision_ranks = Species
subdivision = see article

The recluse spiders (genus "Loxosceles"), also known as fiddle-back or violin spiders, are a venomous genus of spiders known for their necrotic bite. They are members of the family Sicariidae, having formerly been placed in their own family, "Loxoscelidae".

Habitat and appearance

"Loxosceles" is distributed nearly worldwide in warmer areas, and are often known as violin spiders or fiddlebacks. All have six eyes arranged in three groups of two (dyads) and are usually brownish with a darker brown characteristic violin marking on the cephalothorax. Most "Loxosceles" can live for one and a half to two years. Members of both genera can live for very long times without food or water.

The recluse spider family includes about 13 species in the United States, the brown recluse spider ("Loxosceles reclusa") being the best known of these. It is found in a large area of the Midwest, west to Colorado and the New Mexico state line and east to Northern Georgia. Sporadic records from other locations only represent incidental introductions, not established populations.

Other notable members of this genus include the Chilean recluse ("L. laeta") and the Mediterranean recluse ("Loxosceles rufescens").

Venom components and effects

"Loxosceles" spiders, like their cousins in "Sicarius", have potent tissue-destroying venoms containing the dermonecrotic agent, sphingomyelinase D, which is otherwise found only in a few pathogenic bacteria. This venom is highly necrotic in effect, capable of causing lesions (open sores) as large as a US quarter. The wounds take a long time to heal and may require skin grafts. If these open wounds become infected there are often serious consequences. Rarely, the venom is carried by the blood stream to internal organs causing systemic effects.

The Chilean recluse ("Loxosceles laeta") supposedly has a more potent venom, which results in systemic involvement more often. This spider was accidentally introduced to the Los Angeles area (Alhambra, Sierra Madre, and Monterey Park). This spider, however, seems to be confined to a very limited area, even though it has lived there for over 30 years. Other members of the genus that have been tested have venoms similar to the brown recluse and all members of this genus are best avoided. However, the brown recluse and its relatives are not very aggressive and huge populations have been found in houses where the human inhabitants remained unbitten after years of cohabitation.cite journal | author = Vetter R, Barger D | title = An infestation of 2,055 brown recluse spiders (Araneae: Sicariidae) and no envenomations in a Kansas home: implications for bite diagnoses in nonendemic areas | journal = J Med Entomol | volume = 39 | issue = 6 | pages = 948–51 | year = 2002 | pmid = ]

A possible problem with diagnosing a recluse spider bite is that the bite of these spiders is probably both underreported in some areas and over reported generally.cite journal | author = Vetter R, Bush S | title = The diagnosis of brown recluse spider bite is overused for dermonecrotic wounds of uncertain etiology | journal = Ann Emerg Med | volume = 39 | issue = 5 | pages = 544–6 | year = 2002| doi = 10.1067/mem.2002.123594] Unfortunately several diseases can mimic the lesions of a recluse spider bite, including Lyme disease, various fungal and bacterial infections and the first sore of syphilis( [http://spiders.ucr.edu/necrotic.html] ). Therefore it is extremely important to associate the spider directly with the bite, if at all possible, and consider alternative diagnoses if no spider was seen.

Recluse spiders are usually found in the center of space webs made of fungus-like silk, which often contains the remains of their recent meals. The most abundant food items for the Arizona recluse ("Loxosceles arizonica") are night-active ants such as carpenter ants. The brown recluse feeds on whatever small prey is available. This is also true of all sicariids. Loxosceles reclusa have been shown in laboratory experiments to prefer scavenging than actively hunting.cite journal | author = Sandidge J | title = Arachnology: Scavenging by brown recluse spiders | journal = Nature | volume = 426 | issue = 30 | year = 2003 | doi = 10.1038/426030a]

pecies

* "Loxosceles accepta" Chamberlin, 1920 — Peru
* "Loxosceles adelaida" Gertsch, 1967 — Brazil
* "Loxosceles alamosa" Gertsch & Ennik, 1983 — Mexico
* "Loxosceles alicea" Gertsch, 1967 — Peru
* "Loxosceles amazonica" Gertsch, 1967 — Brazil
* "Loxosceles anomala" (Mello-Leitão, 1917) — Brazil
* "Loxosceles apachea" Gertsch & Ennik, 1983 — USA, Mexico
* "Loxosceles aphrasta" Wang, 1994 — China
* "Loxosceles aranea" Gertsch, 1973 — Mexico
* "Loxosceles arizonica" Gertsch & Mulaik, 1940 — USA
* "Loxosceles aurea" Gertsch, 1973 — Mexico
* "Loxosceles baja" Gertsch & Ennik, 1983 — Mexico
* "Loxosceles barbara" Gertsch & Ennik, 1983 — Mexico
* "Loxosceles belli" Gertsch, 1973 — Mexico
* "Loxosceles bettyae" Gertsch, 1967 — Peru
* "Loxosceles blancasi" Gertsch, 1967 — Peru
* "Loxosceles blanda" Gertsch & Ennik, 1983 — USA
* "Loxosceles boneti" Gertsch, 1958 — Mexico, El Salvador
* "Loxosceles candela" Gertsch & Ennik, 1983 — Mexico
* "Loxosceles caribbaea" Gertsch, 1958 — Greater Antilles
* "Loxosceles carmena" Gertsch & Ennik, 1983 — Mexico
* "Loxosceles chinateca" Gertsch & Ennik, 1983 — Mexico
* "Loxosceles colima" Gertsch, 1958 — Mexico
* "Loxosceles conococha" Gertsch, 1967 — Peru
* "Loxosceles coquimbo" Gertsch, 1967 — Chile
* "Loxosceles coyote" Gertsch & Ennik, 1983 — Mexico
* "Loxosceles cubana" Gertsch, 1958 — Cuba, Bahama Islands
* "Loxosceles deserta" Gertsch, 1973 — USA, Mexico
* "Loxosceles devia" Gertsch & Mulaik, 1940 — USA, Mexico
* "Loxosceles fontainei" Millot, 1941 — Guinea
* "Loxosceles foutadjalloni" Millot, 1941 — Guinea
* "Loxosceles francisca" Gertsch & Ennik, 1983 — Mexico
* "Loxosceles frizzelli" Gertsch, 1967 — Peru
* "Loxosceles gaucho" Gertsch, 1967 — Brazil, Tunisia
* "Loxosceles gloria" Gertsch, 1967 — Ecuador, Peru
* "Loxosceles guatemala" Gertsch, 1973 — Guatemala
* "Loxosceles harrietae" Gertsch, 1967 — Peru
* "Loxosceles herreri" Gertsch, 1967 — Peru
* "Loxosceles hirsuta" Mello-Leitão, 1931 — Brazil, Paraguay, Argentina
* "Loxosceles huasteca" Gertsch & Ennik, 1983 — Mexico
* "Loxosceles immodesta" (Mello-Leitão, 1917) — Brazil
* "Loxosceles inca" Gertsch, 1967 — Peru
* "Loxosceles insula" Gertsch & Ennik, 1983 — Mexico
* "Loxosceles intermedia" Mello-Leitão, 1934 — Brazil, Argentina
* "Loxosceles jaca" Gertsch & Ennik, 1983 — Mexico
* "Loxosceles jamaica" Gertsch & Ennik, 1983 — Jamaica
* "Loxosceles jarmila" Gertsch & Ennik, 1983 — Jamaica
* "Loxosceles julia" Gertsch, 1967 — Peru
* "Loxosceles kaiba" Gertsch & Ennik, 1983 — USA
* "Loxosceles lacroixi" Millot, 1941 — Ivory Coast
* "Loxosceles lacta" Wang, 1994 — China
* "Loxosceles laeta" (Nicolet, 1849) — South America, introduced to North America, Finland and Australia
* "Loxosceles lawrencei" Caporiacco, 1955 — Venezuela, Trinidad, Curaçao
* "Loxosceles lutea" Keyserling, 1877 — Colombia, Ecuador
* "Loxosceles luteola" Gertsch, 1973 — Mexico
* "Loxosceles manuela" Gertsch & Ennik, 1983 — Mexico
* "Loxosceles martha" Gertsch & Ennik, 1983 — USA
* "Loxosceles meruensis" Tullgren, 1910 — Tanzania
* "Loxosceles misteca" Gertsch, 1958 — Mexico
* "Loxosceles mulege" Gertsch & Ennik, 1983 — Mexico
* "Loxosceles nahuana" Gertsch, 1958 — Mexico
* "Loxosceles neuvillei" Simon, 1909 — Somalia, East Africa
* "Loxosceles olmea" Gertsch, 1967 — Peru
* "Loxosceles pallidecolorata" (Strand, 1906) — Ethiopia
* "Loxosceles palma" Gertsch & Ennik, 1983 — USA, Mexico
* "Loxosceles panama" Gertsch, 1958 — Panama
* "Loxosceles parrami" Newlands, 1981 — South Africa
* "Loxosceles piura" Gertsch, 1967 — Peru
* "Loxosceles pucara" Gertsch, 1967 — Peru
* "Loxosceles puortoi" Martins, Knysak & Bertani, 2002 — Brazil
* "Loxosceles reclusa" Gertsch & Mulaik, 1940 — North America
* "Loxosceles rica" Gertsch & Ennik, 1983 — Costa Rica
* "Loxosceles rosana" Gertsch, 1967 — Peru
* "Loxosceles rothi" Gertsch & Ennik, 1983 — Mexico
* "Loxosceles rufescens" (Dufour, 1820) — Cosmopolitan
* "Loxosceles rufipes" (Lucas, 1834) — Guatemala, Panama, Colombia
* "Loxosceles russelli" Gertsch & Ennik, 1983 — USA
* "Loxosceles sabina" Gertsch & Ennik, 1983 — USA
* "Loxosceles seri" Gertsch & Ennik, 1983 — Mexico
* "Loxosceles similis" Moenkhaus, 1898 — Brazil
* "Loxosceles smithi" Simon, 1897 — Ethiopia
* "Loxosceles sonora" Gertsch & Ennik, 1983 — Mexico
* "Loxosceles spadicea" Simon, 1907 — Peru, Bolivia, Argentina
* "Loxosceles speluncarum" Simon, 1893 — South Africa
* "Loxosceles spinulosa" Purcell, 1904 — Southern Africa
* "Loxosceles surca" Gertsch, 1967 — Peru
* "Loxosceles taeniopalpis" Simon, 1907 — Ecuador
* "Loxosceles taino" Gertsch & Ennik, 1983 — Bahama Islands, Jamaica, Hispaniola
* "Loxosceles tehuana" Gertsch, 1958 — Mexico
* "Loxosceles tenango" Gertsch, 1973 — Mexico
* "Loxosceles teresa" Gertsch & Ennik, 1983 — Mexico
* "Loxosceles tlacolula" Gertsch & Ennik, 1983 — Mexico
* "Loxosceles valdosa" Gertsch, 1973 — Mexico
* "Loxosceles valida" Lawrence, 1964 — South Africa
* "Loxosceles variegata" Simon, 1897 — Paraguay
* "Loxosceles virgo" Gertsch & Ennik, 1983 — Virgin Islands
* "Loxosceles vonwredei" Newlands, 1980 — Namibia
* "Loxosceles weyrauchi" Gertsch, 1967 — Peru
* "Loxosceles yucatana" Chamberlin & Ivie, 1938 — Mexico, Belize, Guatemala
* "Loxosceles zapoteca" Gertsch, 1958 — Mexico

ee also

* List of Sicariidae species
* Spider families

Footnotes

External links

* [http://www.arachnology.org/Arachnology/Pages/Reclusa.html Arachnology Home Pages: Loxosceles: Recluse spiders]
* [http://www.museums.org.za/bio/spiderweb/sicariid.htm Biodiversity Explorer: Family Sicariidae] (Beautiful photos of "Sicarius" and "Loxosceles"!)
* [http://research.amnh.org/entomology/spiders/catalog81-87/index.html Platnick, N.I. 2003. World Spider Catalog.]
* [http://spiders.ucr.edu/necrotic.html Vetter, R. 2003. Causes of Necrotic Wounds other than Brown Recluse Spider Bites.]
* [http://spiders.ucr.edu/myth.html Vetter, R. 2003. Myth of the Brown Recluse Fact, Fear, and Loathing.]
* [http://www.spiderpicturesandinfo.com/brown-recluse-spider/ Pictures of the Brown Recluse Spider]
* [http://www.forestryimages.org/browse/subimages.cfm?SUB=3438 Pictures of "L. reclusa" and wound] (free for noncommercial use)