| Loxosceles intermedia | |
|---|---|
 | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Subphylum: | Chelicerata |
| Class: | Arachnida |
| Order: | Araneae |
| Infraorder: | Araneomorphae |
| Family: | Sicariidae |
| Genus: | Loxosceles |
| Species: | L. intermedia |
| Binomial name | |
| Loxosceles intermedia Mello-Leitão, 1934 [1] | |
| Synonyms [1] | |
| |
Loxosceles intermedia, the Brazilian brown recluse spider, is a highly venomous spider species in the family Sicariidae native to Brazil and Argentina.
The male has a total length of 5.3 mm, legs I to IV, have a length of 24.5, 31.8, 20.4 and 23.6 mm, the palp can be 5.4 mm long, females are larger, measuring about 8.5 mm in length, with legs ranging from 15.1, 16.0, 13.1 and 15, 5 mm, the palp of females measures 3.8 mm.
Both male and female carapace ranges from dull yellow to orange brown, covered with black and subpretiated bristles. The cephalica pars varies from dark orange-brown to reddish-brown, with a '' U '' shape contrasting with the yellowish pars thoracica. The tubers of the eyes are enlarged, while the lateral marens are not dark, the abdomen is grayish or blackened, with the dorsal part darker than the ventral part, the leg segments vary from orange-brown to reddish-brown. [2]
It is a very shy spider, with nocturnal habits, building irregular webs under fallen tree trunks and debris, usually in dark places. They can also be found in human environments, in socks, clothes, blankets, wardrobes, garages and among others dark places. Their food, as well as that of several recluse spiders, is based on insects such as cockroaches, crickets and beetles. They have been reported to attack other arthropods such as scorpions. It breeds in the hottest months of the year, laying about 20 eggs taking 46 days for the juveniles to hatch. The female builds a bag-shaped web where the eggs are deposited. [3]
Loxosceles intermedia is native to Brazil and Argentina. [1] They are found in temperate and warm regions of South America in southeastern and southern Brazil, as well as northern Argentina.[ citation needed ] They live in dark, very dry cracks, warm regions with elevations below 500 m, quite common around or inside the houses of humans. [4]
As well as the Chilean recluse spider, the venom of Loxosceles intermedia has a high concentration of the enzyme sphingomyelinase D. [5] responsible for local and systemic effects, and is one of the main species attributed to deaths in South America, since the systemic effects of the bite occur frequently. The symptoms are not immediate, which leads the victim to believe that the bite was mild. They usually take hours to manifest, and begins with severe pain, redness, inflammation and blisters, in more severe cases evolving to tissue necrosis. Systemic effects, include hemolysis, cardiac problems, vascular collapse and kidney failure. Loxosceles intermedia bite is also capable of inducing severe thrombocytopenia, increased fibrinogen, reduced clotting factor VII, disseminated intravascular coagulation and severe bleeding. The venom is also capable of inducing myofibril necrosis and leukocyte infiltration causing damage to skeletal muscle. Thrombocytopenia is an important clinical sign for diagnosing L. intermedia bites. Moderate symptoms such as nausea, vomiting, fever and muscle pain are common with Loxosceles bites, especially from this species. The minimum necrotic dose is 2.4 μg / kg. [4] [6]
The lethal dose for four strains of mice ranges from 4.6-24.5 μg. [7] Venom causes dermonecrotic lesions in humans and rabbits, however, rats do not develop this type of lesion. [8] The recombinant toxin Loxtox rLiD1 from the L. intermedia venom is responsible for the cardiotoxic effects, and a significant increase in density I (Ca, L), and intracellular Ca (2+) transients respectively. A sphingomyelinase D protein also plays a key role in cardiac dysfunction. [9] L. intermedia can produce 5.6 mg of venom, the male produces less, around 2.43 mg. [10] While 40 μg of the venom proteins corresponds to the average amount inoculated by the spider. [8]
The brown recluse is a recluse spider with necrotic venom. Similar to those of other recluse spiders, their bites sometimes require medical attention. The brown recluse is one of three spiders in North America with dangerous venom, the others being the black widow and the Chilean recluse.
Phoneutria is a genus of spiders in the family Ctenidae. They are mainly found in northern South America, with one species in Central America. Members of the genus are commonly referred to as Brazilian wandering spiders. Other English names include armed spiders and banana spiders.
The recluse spiders, 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. They are venomous spiders known for their bite, which sometimes produces a characteristic set of symptoms known as loxoscelism.
Sicariidae is a family of six-eyed venomous spiders known for their potentially necrotic bites. The family consists of three genera and about 160 species. Well known spiders in this family include the brown recluse spider and the six-eyed sand spider.
The Mediterranean recluse spider is a species of spider that originated in the Mediterranean region as its name implies, but can now be found in many parts of the world and is listed as one of the most invasive spiders worldwide. Usually dwelling in caves, the spiders will also inhabit basements and tunnels. Their webs shelter their egg sacs, which hatch into young that molt as they grow. The spider hunts at night and eats species including silverfish and cockroaches, and they usually target smaller insects.
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.
Phoneutria nigriventer is a species of medically-significant spider in the family Ctenidae, found in the Southern Cone of South America. Along with other members of the genus, they are often referred to as Brazilian wandering spiders.
Sicarius is a genus of recluse spiders that is potentially medically significant to humans. It is one of three genera in its family, all venomous spiders known for a bite that can induce loxoscelism. They live in deserts and arid regions of the Neotropics, and females use a mixture of sand and silk when producing egg sacs. The name is Latin for assassin.
The Chilean recluse spider, Loxosceles laeta, is a highly venomous spider of the family Sicariidae. In Spanish, it is known as araña de rincón, or "corner spider"; in Brazilian Portuguese, as aranha-marrom or "brown spider". It is considered by many to be the most dangerous of recluse spiders, and its bites often result in serious systemic reactions, up to and including death.
Loxoscelism is a condition occasionally produced by the bite of the recluse spiders. The area becomes dusky and a shallow open sore forms as the skin around the bite dies (necrosis). It is the only proven type of necrotic arachnidism in humans. While there is no known therapy effective for loxoscelism, there has been research on antibiotics, surgical timing, hyperbaric oxygen, potential antivenoms and vaccines. Because of the number of diseases that may mimic loxoscelism, it is frequently misdiagnosed by physicians.
Loxosceles deserta, commonly known as the desert recluse, is a recluse spider of the family Sicariidae. It is found in Mexico and the United States.
The pathophysiology of a spider bite is due to the effect of its venom. A spider envenomation occurs whenever a spider injects venom into the skin. Not all spider bites inject venom – a dry bite, and the amount of venom injected can vary based on the type of spider and the circumstances of the encounter. The mechanical injury from a spider bite is not a serious concern for humans. Some spider bites do leave a large enough wound that infection may be a concern. However, it is generally the toxicity of spider venom that poses the most risk to human beings; several spiders are known to have venom that can cause injury to humans in the amounts that a spider will typically inject when biting.
Hexophthalma is a genus of spiders in the family Sicariidae. Although the genus was originally erected in 1878, it was merged into the genus Sicarius in the 1890s, and remained unused until revived in 2017, when it was discovered that the African species then placed in Sicarius were distinct. The English name six-eyed sand spiders is used for members of the genus, particularly Hexophthalma hahni.
Sicarius thomisoides is a species of spider in the family Sicariidae, found in Chile. It is the type species of the genus Sicarius. Its correct name has been the source of confusion. It has often been known by the synonym Sicarius terrosus, a name which has also often been used incorrectly for other species.
Sicarius ornatus is a species of venomous spider found in South America (Brazil). It has a highly toxic venom like the other South American sicariid, Loxosceles laeta and the African Hexophthalma hahni, but there are few human bites recorded. Its venom has active sphingomyelinase D, and can lead to a severe pathology.
Sicarius tropicus is a species of six-eyed sand spider (Sicarius) endemic in South American caatinga in Brazil. Like related spiders, it is venomous, but only one medically-significant bite has been recorded, causing dermonecrotic lesions in a 17-year-old boy.
Loxosceles gaucho commonly known in English as the gaucho spider. is a highly venomous recluse spider endemic to South America.
Loxosceles similis, is a species of a venomous recluse spider endemic to South America.