Loxosceles laeta

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Loxosceles laeta
Loxosceles laeta

Loxosceles laeta

Systematics
Subordination : Real spiders (Araneomorphae)
Partial order : Haplogynae
Superfamily : Scytodoidea
Family : Sicariidae
Genre : Loxosceles
Type : Loxosceles laeta
Scientific name
Loxosceles laeta
( Nicolet , 1849)

Loxosceles laeta is a spider from the family of Sicariidae (formerly Family Loxoscelidae) with deposits, particularly in South America , there especially Chile - hence the commonly held designation as "Chilean angle Spider" ( Spanish araña de rincón chilena ) or "Chilean recluse spider" ( English Chilean Recluse Spider ). The Spanish name indicates its occurrence in dark nooks and crannies z. B. from cupboards or rooms. Contrary to the name, it does not belong to the taxonomic genus of Tegenaria ( angle spiders ).

Loxosceles laeta is one of the poisonous spiders that are life-threatening for humans. A well-known North American relative is Loxosceles reclusa . However, occurrences of L. laeta have also been reported in North America .

features

In the female sex, the species reaches a body length of 7 to 15, on average about 12 millimeters, the males are smaller (6 to 12 millimeters). The prosoma (or carapace) is on average 5.6 millimeters long and 4.5 millimeters wide. With outstretched legs, the animals reach a diameter of 3 to 5 cm. Prosoma, legs and palps are colored in a shade from yellow to orange to red-brown, with young animals being lighter than older ones, and typically almost monochrome without distinctive markings. Sometimes the front part around the eyes is drawn with darker lines; it then results in the indicated, typical "violin" drawing of the genre. The abdomen is colored white or light gray. The entire body is usually covered with dark hair, which makes it appear relatively gloomy. The six eyes are relatively small, the two rows of eyes are strongly curved, so that the imaginary connecting line between the front edges of the front side eyes is about one eye diameter behind the central eyes.

At least 24 species of the laeta group have been described from South America . The species Loxosceles laeta can be distinguished from most related species by its leg formula 4213, i. H. the fourth pair of legs is the longest, followed by the second, first and third. Typical for all species of the laeta species group is the shape of the last leg links (tarsi) of the males, which are quite narrow, in any case longer than wide and never broadened into a rounded lobe. One thing is certain Loxosceles laeta of similar types only by their sexual characteristics distinguishable: In the male the embolus of palp is very short, no longer than the length of the bulb, and the tibia of the palp is more than twice as long as wide. The species can also be distinguished from other species found in North and Central America by the Gertsch and Ennik key. As a rule, like its relatives, the spider moves very quickly and with agility.

biology

The way of life of the kind corresponds to that of the other kinds of the kind. They are nocturnal hunters who hunt freely and do not spin webs to acquire prey. They use their spider silk to create a hideout in a crevice or cavity in which they spend the daytime hours. The animals reach sexual maturity after one year and can then live two to four years, in the laboratory up to seven years. They can survive without food for more than a year.

distribution

The species is very common in western South America (Chile, Peru and Ecuador), where its original home is also assumed. It was carried off to other regions by trade and traffic. Today it can be found all over South and Central America from Argentina to Belize. In Chile it is the only representative of its genus, while Loxosceles gaucho also occur in Argentina and Loxosceles intermedia in Brazil and Loxosceles reclusa dominates in North America . Loxosceles rufescens can be found in the Mediterranean region . Loxosceles species mostly live in human dwellings or in their immediate vicinity. According to older surveys (1963), around every third household is affected in Santiago de Chile ; other studies have found the species in about 40% of households in urban areas of Chile and about 25% of houses in the countryside. The difference is attributed to the increased presence of Scytodes globula (tiger spider) in rural households, a natural enemy of Loxosceles laeta . In general, advisory literature and population information today assume that the spider is present in practically every Chilean household, and appropriate precautionary measures are called for. The spider appears much more frequently in the summer season than in winter.

The species is rare in North America and is believed to be found in heated buildings. Finds in storage rooms and cellars have been documented since 1960. In 1972 Loxosceles laeta was also found in the basement of the Zoological Institute of the University of Helsinki in Finland . In the San Francisco Bay area of ​​California, large populations are known to be found in underground tunnels of the supply systems of shopping malls; However, encounters with people or cases of poisoning hardly ever occur here.

Bite accidents and toxicity

Loxosceles laeta is considered to be the Loxosceles species with the most dangerous bite, especially since no real antidote is known. However, because it is nocturnal and not aggressive, bites are relatively rare. According to the Chilean health authorities, a total of 43 deaths from spider bites ( Loxosceles laeta and Latrodectus mactans ) were counted between 1985 and 1995 . Most bite accidents take place in the bedroom while getting dressed or while sleeping in bed. In most cases, the face or limbs are affected. The bite is very painful, is perceived as a sudden stinging or burning sensation, and usually does not go unnoticed. Within two to eighteen hours after the bite, increasing pain develops around the bite site. The poison causes severe tissue damage and can lead to death from liver failure . The mortality rate is given as three to four percent of those bitten. The strength of the poisonous effect is largely influenced by how long the spider fasted before the bite (the longer it was before the last food intake, the more poisonous a bite appears). The severity and severity of the symptoms of intoxication also depend on the disposition of those affected; in general, the symptoms are particularly severe in children.

In order to avoid bites, it is recommended that dark corners and nooks and crannies in living rooms and cupboards that have hardly been touched are cleaned regularly with a vacuum cleaner during the day and especially in summer and that insecticide is applied to the appropriate places. Items of clothing from rarely used wardrobe areas should be shaken out before getting dressed. Protective measures are also necessary in the workplace in dark, little-used areas. As with all spider bites, it is strongly recommended to catch the animal after a bite if possible and to bring it to the hospital outpatient department in a closed glass container so that the type and required antidote can be reliably determined. The main endangerment period from Loxosceles laeta in Chile begins around October and lasts six to eight months.

literature

  • Willis J. Gertsch : The spider genus Loxosceles in South America (Araneae, Scytodidae). In: Bulletin of the American Museum of Natural History , Vol. 136 (1967), Issue 3, pp. 121-173 u. Fig. (Panels).
  • Willis J. Gertsch, Franklin Ennik : The spider genus Loxosceles in North America, Central America, and the West Indies (Araneae, Loxoscelidae). In: Bulletin of the American Museum of Natural History , Vol. 175 (1983), No. 3, pp. 264-360.

Web links

Commons : Loxosceles laeta  - Collection of images, videos and audio files

Individual evidence

  1. ↑ a b c Arañas de rincón: cómo identificarlas y que hacer en caso de mordedura. In: Ladera Sur , January 19, 2019, accessed on March 14, 2020.
  2. ↑ DC Lowrie (1980): Starvation Longevity Of Loxosceles laeta (Nicolet) (Araneae). Entomological News 91: 130-132.
  3. ↑ Demitri Parra: Loxosceles laeta, identificación y una mirada bajo microscopía de barrido (PDF file; 1004 kB). In: SciELO Chile , Vol. 57 (2002), No. 1/2, p. 75.
  4. ↑ Marta Luciane Fischer & João Vasconcellos-Net (2005): Microhabitats Occupied by Loxosceles intermedia and Loxosceles laeta (Araneae: Sicariidae) in Curitiba, Paraná, Brazil. Journal of Medical Entomology 42 (5): 756-765. doi : 10.1603 / 0022-2585 (2005) 042 [0756: MOBLIA] 2.0.CO; 2
  5. ↑ a b c d Alejandro Palma ( Universidad de Concepción ): Loxocelismo , online material (publication status 2000, last accessed in 2018).
  6. ↑ a b c Araña de rincon chilena: ¿Qué tan bien la conoces? Article on the Chilean insect portal hablemosdeinsectos.com (last accessed in 2018).
  7. Jump up ↑ Richard S. Vetter, Paula E. Cushing, Rodney L. Crawford, Lynn A. Royce (2003): Diagnoses of brown recluse spider bites (loxoscelism) greatly outnumber actual verifications of the spider in four western American states. Toxicon 42: 413-418. doi : 10.1016 / S0041-0101 (03) 00173-9
  8. ↑ Demitri Parra: Loxosceles laeta, identificación y una mirada bajo microscopía de barrido. In: SciELO Chile , Vol. 57 (2002), No. 1/2, pp. 75-78 (here: p. 75 and note 2, with reference to J. M. Futrell: Loxoscelism. In: American Journal of the Medical Sciences, 304: 261-267 (1992)).
  9. ↑ Chile: El Niño climatic phenomenon causes poisonous spiders to multiply. In: latinapress , December 30, 2015, accessed June 1, 2018.
  10. ↑ Alejandro Palma: Loxocelismo , online material (publication as of 2000, bullet 10.4).
  11. ↑ Demitri Parra: Loxosceles laeta, identificación y una mirada bajo microscopía de barrido. In: SciELO Chile , Vol. 57 (2002), No. 1/2, pp. 75-78 (here: pp. 75 f.).
  12. ↑ a b c d Beatriz Burgos: El mayor riesgo por picadura de araña de rincón comienza en el mes de octubre: Prevención y diagnóstico. Bayer HealthCare Chile, accessed 2018.