Recluse spider

Recluse spider; Temporal range: Neogene– Present PreꞒ Ꞓ O S D C P T J K Pg N
	Loxosceles gaucho, Brazil
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Chelicerata
Class:	Arachnida
Order:	Araneae
Infraorder:	Araneomorphae
Family:	Sicariidae
Genus:	Loxosceles; Heineken & Lowe, 1832[1]
Type species
	L. rufescens; (Dufour, 1820)
Species
	139, see text
Synonyms[1]
	Calheirosia Mello-Leitão, 1917[2]; Loxoscella Strand, 1906[3];

The recluse spiders (Loxosceles (/lɒkˈsɒsɪliːz/), also known as brown spiders, fiddle-backs, violin spiders, and reapers, is a genus of spiders that was first described by R. T. Lowe in 1832.[4] They are venomous spiders known for their bite, which sometimes produces a characteristic set of symptoms known as loxoscelism.

Recluse spiders are now identified as members of the family Sicariidae, having formerly been placed in their own family, the Loxoscelidae. Although recluse spiders are feared, they are usually not aggressive.[5]

Relation with other spiders

Sicariidae are of the superfamily Scytodoidea. Other families in the Scytodoidea include Drymusidae, Scytodidae, and Periegopidae.

Habitat and appearance

Loxosceles is distributed nearly worldwide in warmer areas. All have six eyes arranged in three groups of two (dyads) and some are brownish with a darker brown characteristic violin marking on the cephalothorax. However, the "violin marking" cannot be used as a reliable way to identify the spider as thousands of species of spider have similar markings. Spiders come with many markings varying greatly within the same species. Most Loxosceles can live for one and a half to two years. Many species of this genus can live for very long times without food or water. They are about 7–12 mm long.

The most common and most famous species in the United States is the brown recluse spider (Loxosceles reclusa). 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. The brown recluse feeds on whatever small prey is available, and has been observed to prefer scavenging over actively hunting.[6] Other notable members of this genus include the Chilean recluse spider (L. laeta) and the Mediterranean recluse spider (L. rufescens).

Recently, concerns have been raised regarding recluses spreading faster due to warmer air carrying them farther as a result of changing climate. On the contrary, newly hatched recluses do not travel via ballooning and thus the populations are confined to very tight spaces with dense populations.[7]

Venom components and effects

Loxosceles spiders, like Hexophthalma species, have potent tissue-destroying venoms containing the dermonecrotic agent, sphingomyelinase D, which is otherwise found only in a few pathogenic bacteria.[8] Recent research has indicated the venom is composed largely of sulfated nucleosides, though these compounds are relatively new discoveries, so little is known about them.[9] The venom produces necrotic lesions that are slow to heal and may require skin grafts. Rarely, the venom is carried by the bloodstream, causing red blood cell destruction.

The venom is identical in male and female spiders, but females can have almost twice the concentration of toxins.[10] For unknown reasons, the toxicity of the venom to mammalian species varies; recluse bites may cause necrosis in humans, rabbits, and guinea pigs, but not in mice or rats.[10]

The Chilean recluse (L. laeta) supposedly has a more potent venom, which results in systemic involvement more often. All Loxosceles species that have been tested have venoms similar to that of the brown recluse and all should be avoided. In general, though, they are not aggressive and commonly occupy human dwellings without causing problems.[11]

Many types of skin wounds are mistaken for or assumed to be the result of a recluse spider bite.[12] Several diseases can mimic the lesions of the bite, including Lyme disease, various fungal and bacterial infections, and the first sore of syphilis.[13] It is important to associate the spider directly with the bite to avoid improper treatment, and to successfully treat common infections or other conditions if no spider was seen.

Bites most often occur as a defense when the spider is trapped against the skin, in clothing, for example.[7] Insecticides often fail to kill the spider, instead intoxicating its nervous system and inducing erratic behavior.[14]

The bite of a recluse spider can generally be categorized into one of the following groups:[7]

Unremarkable - self-healing minute damage
Mild reaction - self-healing damage with itchiness, redness, patterns of aggressive behavior and a mild lesion.
Dermonecrotic - the uncommon, "classic" recluse bite, producing a necrotic skin lesion. About 66% of necrotic bite lesions heal with no complications.[15] In extreme cases, the lesion may be up to 40 centimeters wide, last for several months, and heal with a permanent scar.[7]
Systemic or viscerocutaneous - an extremely rare, systemic reaction to envenomation of the bloodstream. It is observed more often in children.[7]

Most bites are unremarkable or mild.[16][17][18]

Species

As of July 2019 it contains 139 species, found in Central America, the Caribbean, Oceania, Asia, Africa, North America, Europe, and South America:[1]

L. accepta Chamberlin, 1920 – Peru
L. adelaida Gertsch, 1967 – Brazil
L. alamosa Gertsch & Ennik, 1983 – Mexico
L. alicea Gertsch, 1967 – Peru
L. amazonica Gertsch, 1967 – Peru, Brazil
L. anomala (Mello-Leitão, 1917) – Brazil
L. apachea Gertsch & Ennik, 1983 – USA, Mexico
L. aphrasta Wang, 1994 – China
L. aranea Gertsch, 1973 – Mexico
L. arizonica Gertsch & Mulaik, 1940 – USA
L. aurea Gertsch, 1973 – Mexico
L. baja Gertsch & Ennik, 1983 – Mexico
L. barbara Gertsch & Ennik, 1983 – Mexico
L. belli Gertsch, 1973 – Mexico
L. bentejui Planas & Ribera, 2015 – Canary Is.
L. bergeri Strand, 1906 – Namibia
L. bettyae Gertsch, 1967 – Peru
L. blancasi Gertsch, 1967 – Peru
L. blanda Gertsch & Ennik, 1983 – USA
L. boneti Gertsch, 1958 – Mexico, El Salvador
L. candela Gertsch & Ennik, 1983 – Mexico
L. carabobensis González-Sponga, 2010 – Venezuela
L. cardosoi Bertani, von Schimonsky & Gallão, 2018 – Brazil
L. caribbaea Gertsch, 1958 – Greater Antilles
L. carinhanha Bertani, von Schimonsky & Gallão, 2018 – Brazil
L. carmena Gertsch & Ennik, 1983 – Mexico
L. cederbergensis Lotz, 2017 – South Africa
L. chapadensis Bertani, Fukushima & Nagahama, 2010 – Brazil
L. chinateca Gertsch & Ennik, 1983 – Mexico
L. colima Gertsch, 1958 – Mexico
L. conococha Gertsch, 1967 – Peru
L. coquimbo Gertsch, 1967 – Chile
L. corozalensis González-Sponga, 2010 – Venezuela
L. coyote Gertsch & Ennik, 1983 – Mexico
L. cubana Gertsch, 1958 – Cuba, Bahama Is., HIspaniola
L. cubiroensis González-Sponga, 2010 – Venezuela
L. curimaguensis González-Sponga, 2010 – Venezuela
L. dejagerae Lotz, 2017 – South Africa
L. deserta Gertsch, 1973 – USA, Mexico
L. devia Gertsch & Mulaik, 1940 – USA, Mexico
L. diaguita Brescovit, Taucare-Ríos, Magalhaes & Santos, 2017 – Chile
L. ericsoni Bertani, von Schimonsky & Gallão, 2018 – Brazil
L. fontainei Millot, 1941 – Guinea
L. foutadjalloni Millot, 1941 – Guinea
L. francisca Gertsch & Ennik, 1983 – Mexico
L. frizzelli Gertsch, 1967 – Peru
L. gaucho Gertsch, 1967 – Brazil. Introduced to Tunisia
L. gloria Gertsch, 1967 – Ecuador, Peru
L. griffinae Lotz, 2017 – Namibia
L. guajira Cala-Riquelme, Gutiérrez-Estrada & Flórez, 2015 – Colombia
L. guatemala Gertsch, 1973 – Guatemala
L. guayota Planas & Ribera, 2015 – Canary Is.
L. haddadi Lotz, 2017 – South Africa
L. harrietae Gertsch, 1967 – Peru
L. herreri Gertsch, 1967 – Peru
L. hirsuta Mello-Leitão, 1931 – Brazil, Paraguay, Argentina
L. huasteca Gertsch & Ennik, 1983 – Mexico
L. hupalupa Planas & Ribera, 2015 – Canary Is.
L. immodesta (Mello-Leitão, 1917) – Brazil
L. inca Gertsch, 1967 – Peru
L. insula Gertsch & Ennik, 1983 – Mexico
L. intermedia Mello-Leitão, 1934 – Brazil, Argentina
L. irishi Lotz, 2017 – Namibia
L. jaca Gertsch & Ennik, 1983 – Mexico
L. jamaica Gertsch & Ennik, 1983 – Jamaica
L. jarmila Gertsch & Ennik, 1983 – Jamaica
L. julia Gertsch, 1967 – Peru
L. kaiba Gertsch & Ennik, 1983 – USA
L. karstica Bertani, von Schimonsky & Gallão, 2018 – Brazil
L. lacroixi Millot, 1941 – Ivory Coast
L. lacta Wang, 1994 – China
L. laeta (Nicolet, 1849) – South America. Introduced to USA, Finland, Australia
L. lawrencei Caporiacco, 1955 – Venezuela, Trinidad, Curaçao
L. lutea Keyserling, 1877 – Colombia, Ecuador
L. luteola Gertsch, 1973 – Mexico
L. mahan Planas & Ribera, 2015 – Canary Is.
L. maisi Sánchez-Ruiz & Brescovit, 2013 – Cuba
L. makapanensis Lotz, 2017 – South Africa
L. malintzi Valdez-Mondragón, Cortez-Roldán, Juárez-Sánchez & Solís-Catalán, 2018 – Mexico
L. manuela Gertsch & Ennik, 1983 – Mexico
L. maraisi Lotz, 2017 – Namibia
L. martha Gertsch & Ennik, 1983 – USA
L. meruensis Tullgren, 1910 – Ethiopia, Kenya, Tanzania
L. misteca Gertsch, 1958 – Mexico
L. mogote Sánchez-Ruiz & Brescovit, 2013 – Cuba
L. mrazig Ribera & Planas, 2009 – Tunisia
L. mulege Gertsch & Ennik, 1983 – Mexico
L. muriciensis Fukushima, de Andrade & Bertani, 2017 – Brazil
L. nahuana Gertsch, 1958 – Mexico
L. neuvillei Simon, 1909 – Ethiopia, Somalia, East Africa
L. niedeguidonae de Andrade, Bertani, Nagahama & Barbosa, 2012 – Brazil
L. olivaresi González-Sponga, 2010 – Venezuela
L. olmea Gertsch, 1967 – Peru
L. pallalla Brescovit, Taucare-Ríos, Magalhaes & Santos, 2017 – Chile
L. pallidecolorata (Strand, 1906) – Ethiopia, Kenya
L. palma Gertsch & Ennik, 1983 – USA, Mexico
L. panama Gertsch, 1958 – Panama
L. parramae Newlands, 1981 – South Africa
L. persica Ribera & Zamani, 2017 – Iran
L. pilosa Purcell, 1908 – Namibia, South Africa
L. piura Gertsch, 1967 – Peru
L. pucara Gertsch, 1967 – Peru
L. puortoi Martins, Knysak & Bertani, 2002 – Brazil
L. reclusa Gertsch & Mulaik, 1940 – North America
L. rica Gertsch & Ennik, 1983 – Costa Rica
L. rosana Gertsch, 1967 – Peru
L. rothi Gertsch & Ennik, 1983 – Mexico
L. rufescens (Dufour, 1820) (type) – Southern Europe, northern Africa to Iran. Introduced to USA, Mexico, Macaronesia, South Africa, India, China, Japan, Korea, Laos, Thailand, Australia, Hawaii
L. rufipes (Lucas, 1834) – Guatemala, Panama, Colombia. Introduced to West Africa
L. russelli Gertsch & Ennik, 1983 – USA
L. sabina Gertsch & Ennik, 1983 – USA
L. sansebastianensis González-Sponga, 2010 – Venezuela
L. seri Gertsch & Ennik, 1983 – Mexico
L. similis Moenkhaus, 1898 – Brazil
L. simillima Lawrence, 1927 – Southern Africa
L. smithi Simon, 1897 – Ethiopia, Malawi, Kenya, Tanzania
L. sonora Gertsch & Ennik, 1983 – Mexico
L. spadicea Simon, 1907 – Peru, Bolivia, Argentina
L. speluncarum Simon, 1893 – South Africa
L. spinulosa Purcell, 1904 – South Africa
L. surca Gertsch, 1967 – Peru, Chile
L. taeniopalpis Simon, 1907 – Ecuador
L. taino Gertsch & Ennik, 1983 – Bahama Is., Jamaica, Hispaniola
L. tazarte Planas & Ribera, 2015 – Canary Is.
L. tehuana Gertsch, 1958 – Mexico
L. tenango Gertsch, 1973 – Mexico
L. tenochtitlan Valdez-Mondragón, 2019 – Mexico
L. teresa Gertsch & Ennik, 1983 – Mexico
L. tibicena Planas & Ribera, 2015 – Canary Is.
L. tlacolula Gertsch & Ennik, 1983 – Mexico
L. troglobia Souza & Ferreira, 2018 – Brazil
L. valdosa Gertsch, 1973 – Mexico
L. vallenar Brescovit, Taucare-Ríos, Magalhaes & Santos, 2017 – Chile
L. variegata Simon, 1897 – Paraguay
L. virgo Gertsch & Ennik, 1983 – Virgin Is.
L. vonwredei Newlands, 1980 – Namibia
L. weyrauchi Gertsch, 1967 – Peru
L. willianilsoni Fukushima, de Andrade & Bertani, 2017 – Brazil
L. yucatana Chamberlin & Ivie, 1938 – Mexico, Belize, Guatemala
L. zapoteca Gertsch, 1958 – Mexico

gollark: And/or not speaking English well for some reason, possibly.

gollark: <@!249056455552925697> So that they don't waste time with people with some amount of sanity.

gollark: Why? Isn't it kind of annoying to do much on a small touchscreen versus an actual PC?

gollark: I personally use "amaze" or something, which mostly works, but I don't exactly do much file exploring on my phone.

gollark: Hmm, perhaps I should actually read that copy of The Art of Electronics I got off archive.org ages ago considering the newly announced announcement.

References

"Gen. Loxosceles Heineken & Lowe, 1832". World Spider Catalog Version 20.0. Natural History Museum Bern. 2019. doi:10.24436/2. Retrieved 2019-08-26.
Brignoli, P. M. (1978). "Spinnen aus Brasilien, II. Vier neue Ochyroceratidae aus Amazonas nebst Bemerkungen über andere Amerikanische Arten (Arachnida: Araneae)". Studies on Neotropical Fauna and Environment. 13: 18.
Gertsch, W. J.; Ennik, F. (1983). "The spider genus Loxosceles in North America, Central America, and the West Indies (Araneae, Loxoscelidae)". Bulletin of the American Museum of Natural History. 175: 277.
Lowe, R. T. (1832). "Descriptions of two species of Araneidae, natives of Madeira". The Zoological Journal. 5: 320–323.
Binkovitz, Leah. "Why We Should All Celebrate Save a Spider Day". Smithsonian. Retrieved 2017-07-17.
Sandidge, J. (2003). "Arachnology: Scavenging by brown recluse spiders". Nature. 426 (30): 30. Bibcode:2003Natur.426...30S. doi:10.1038/426030a. PMID 14603305.
Vetter, R. S. (2008). "Spiders of the genus Loxosceles: a review of biological, medical and psychological aspects regarding envenomations" (PDF). Journal of Arachnology. 36 (3): 150–163. doi:10.1636/RSt08-06.1.
Binford, G. J.; et al. (2005). "Sphingomyelinase D from venoms of Loxosceles spiders: evolutionary insights from cDNA sequences and gene structure" (PDF). Toxicon. 45 (5): 547–560. doi:10.1016/j.toxicon.2004.11.011. PMID 15777950.
Schroeder, F. C.; et al. (2008). "NMR-spectroscopic screening of spider venom reveals sulfated nucleosides as major components for the brown recluse and related species". PNAS. 105 (38): 14283–14287. Bibcode:2008PNAS..10514283S. doi:10.1073/pnas.0806840105. PMC 2567178. PMID 18794518.
Swanson, D. L.; Vetter, R. S. (2006). "Loxoscelism" (PDF). Clinics in Dermatology. 24 (3): 213–221. doi:10.1016/j.clindermatol.2005.11.006. PMID 16714202. Retrieved 12 April 2011.
Vetter, R. and D. Barger. (2002). "An infestation of 2,055 brown recluse spiders (Araneae: Sicariidae) and no envenomations in a Kansas home: implications for bite diagnoses in nonendemic areas". J Med Entomol. 39 (6): 948–51. doi:10.1603/0022-2585-39.6.948. PMID 12495200.
Vetter, R. and S. Bush. (2002). "The diagnosis of brown recluse spider bite is overused for dermonecrotic wounds of uncertain etiology". Ann Emerg Med. 39 (5): 544–6. doi:10.1067/mem.2002.123594. PMID 11973562.
"UCR Spiders Site". Retrieved 28 October 2014.
Hite, J. M. (1966). The biology of the brown recluse spider. Kansas State University.
Pauli, I.; et al. (2006). "The efficacy of antivenom in loxoscelism treatment". Toxicon. 48 (2): 123–37. doi:10.1016/j.toxicon.2006.05.005.
Wright, S. W.; et al. (1997). "Clinical presentation and outcome of brown recluse spider bite". Annals of Emergency Medicine. 30: 28–32. doi:10.1016/S0196-0644(97)70106-9. PMID 9209221.
Anderson, P. C. (1998). "Missouri brown recluse spider: a review and update". Missouri Medicine. 95 (7): 318–22. PMID 9666677.
Cacy, J. and J. W. Mold. (1999). "The clinical characteristics of brown recluse spider bites treated by family physicians: an OKPRN study". Journal of Family Practice. 48 (7): 536–42. PMID 10428252.

External links

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[WSC_g3087-1] "Gen. Loxosceles Heineken & Lowe, 1832". World Spider Catalog Version 20.0. Natural History Museum Bern. 2019. doi:10.24436/2. Retrieved 2019-08-26.

[Brig1978-2] Brignoli, P. M. (1978). "Spinnen aus Brasilien, II. Vier neue Ochyroceratidae aus Amazonas nebst Bemerkungen über andere Amerikanische Arten (Arachnida: Araneae)". Studies on Neotropical Fauna and Environment. 13: 18.

[Gert1983-3] Gertsch, W. J.; Ennik, F. (1983). "The spider genus Loxosceles in North America, Central America, and the West Indies (Araneae, Loxoscelidae)". Bulletin of the American Museum of Natural History. 175: 277.

[Lowe1832-4] Lowe, R. T. (1832). "Descriptions of two species of Araneidae, natives of Madeira". The Zoological Journal. 5: 320–323.

[5] Binkovitz, Leah. "Why We Should All Celebrate Save a Spider Day". Smithsonian. Retrieved 2017-07-17.

[Arachnology2003-Sandidge-6] Sandidge, J. (2003). "Arachnology: Scavenging by brown recluse spiders". Nature. 426 (30): 30. Bibcode:2003Natur.426...30S. doi:10.1038/426030a. PMID 14603305.

[vetter-7] Vetter, R. S. (2008). "Spiders of the genus Loxosceles: a review of biological, medical and psychological aspects regarding envenomations" (PDF). Journal of Arachnology. 36 (3): 150–163. doi:10.1636/RSt08-06.1.

[binford-8] Binford, G. J.; et al. (2005). "Sphingomyelinase D from venoms of Loxosceles spiders: evolutionary insights from cDNA sequences and gene structure" (PDF). Toxicon. 45 (5): 547–560. doi:10.1016/j.toxicon.2004.11.011. PMID 15777950.

[schroeder-9] Schroeder, F. C.; et al. (2008). "NMR-spectroscopic screening of spider venom reveals sulfated nucleosides as major components for the brown recluse and related species". PNAS. 105 (38): 14283–14287. Bibcode:2008PNAS..10514283S. doi:10.1073/pnas.0806840105. PMC 2567178. PMID 18794518.

[Swanson-Vetter-10] Swanson, D. L.; Vetter, R. S. (2006). "Loxoscelism" (PDF). Clinics in Dermatology. 24 (3): 213–221. doi:10.1016/j.clindermatol.2005.11.006. PMID 16714202. Retrieved 12 April 2011.

[JMedEntomol2002-Vetter-11] Vetter, R. and D. Barger. (2002). "An infestation of 2,055 brown recluse spiders (Araneae: Sicariidae) and no envenomations in a Kansas home: implications for bite diagnoses in nonendemic areas". J Med Entomol. 39 (6): 948–51. doi:10.1603/0022-2585-39.6.948. PMID 12495200.

[annemergmed2002-Vetter-12] Vetter, R. and S. Bush. (2002). "The diagnosis of brown recluse spider bite is overused for dermonecrotic wounds of uncertain etiology". Ann Emerg Med. 39 (5): 544–6. doi:10.1067/mem.2002.123594. PMID 11973562.

[13] "UCR Spiders Site". Retrieved 28 October 2014.

[Hite-14] Hite, J. M. (1966). The biology of the brown recluse spider. Kansas State University.

[pauli-15] Pauli, I.; et al. (2006). "The efficacy of antivenom in loxoscelism treatment". Toxicon. 48 (2): 123–37. doi:10.1016/j.toxicon.2006.05.005.

[wright-16] Wright, S. W.; et al. (1997). "Clinical presentation and outcome of brown recluse spider bite". Annals of Emergency Medicine. 30: 28–32. doi:10.1016/S0196-0644(97)70106-9. PMID 9209221.

[anderson-17] Anderson, P. C. (1998). "Missouri brown recluse spider: a review and update". Missouri Medicine. 95 (7): 318–22. PMID 9666677.

[cacy-18] Cacy, J. and J. W. Mold. (1999). "The clinical characteristics of brown recluse spider bites treated by family physicians: an OKPRN study". Journal of Family Practice. 48 (7): 536–42. PMID 10428252.