The book of earth

The coneweb spiders of the family Diguetidae are six-eyed haplogyne (lacking hardened female genitalia, or epigyne) spiders that live in tangled space webs. They fashion a cone-like central retreat in which they hide and lay eggs. The family is small (two genera and only 15 species) and is confined to the New World, where it is usually found in deserts. Members of the genus Diguetia usually build their webs in shrubs or between cactus pads. Although they have the same eye arrangement as the venomous recluse spiders (family Sicariidae), none of these genera are known to be harmful to humans.[citation needed]

The Diguetidae are sometimes considered a subfamily of the Plectreuridae.

Taxonomy

The group was first created by F. O. Pickard-Cambridge in 1899 as the subfamily Diguetiinae of the family Scytodidae. It was raised to the rank of family by Willis J. Gertsch using the spelling "Diguetidae". Pickard-Cambridge's use of double "i" is correct according to Article 29.3 of the International Code of Zoological Nomenclature, since the name is based on the genus Diguetia. In 2004, Jörg Wonderlich suggested reducing it again to a subfamily, but now of the family Plectreuridae.

Genera and species

As of May 2016, the World Spider Catalog accepted the following genera and species:

Diguetia Simon, 1895

Diguetia albolineata (O. Pickard-Cambridge, 1895) – USA, Mexico
Diguetia andersoni Gertsch, 1958 – USA
Diguetia canities (McCook, 1889) (type species) – USA, Mexico
Diguetia catamarquensis (Mello-Leitão, 1941) – Argentina
Diguetia imperiosa Gertsch & Mulaik, 1940 – USA, Mexico
Diguetia mojavea Gertsch, 1958 – USA
Diguetia propinqua (O. Pickard-Cambridge, 1896) – Mexico
Diguetia signata Gertsch, 1958 – USA, Mexico
Diguetia stridulans Chamberlin, 1924 – Mexico
Segestrioides Keyserling, 1883

Segestrioides badia (Simon, 1903) – Brazil
Segestrioides bicolor Keyserling, 1883 (type species) – Peru
Segestrioides copiapo Platnick, 1989 – Chile
Segestrioides tofo Platnick, 1989 – Chile
^

source - Wikipedia
if u like the post please like and shear

Because the study material is quite expensive, not all can buy it. The RBbox does the same small cache of the same information and study material to reach you for free. You also help in making this case successful by cooperating. You also have some information that you can send to others as a post or article. We will publish it with your name and picture. www.rbbox.in

The Chilean rose tarantula (Grammostola rosea), also known as the rose hair tarantula, the Chilean fire tarantula or the Chilean red-haired tarantula (depending on the color morph), is probably the most common species of tarantula available in American and European pet stores today, due to the large number of wild-caught specimens exported cheaply from their native Chile into the pet trade. The species is also known from Bolivia and Argentina.

G. rosea is a common pet of tarantula hobbyists. Females have been known to live as long as 15–20 years, but due to the limited time they have been available on the market (and hence for extensive study) it is possible that they may live considerably longer than 20 years. There is considerable confusion between this species and Grammostola porteri, with some arguing that many of the "G. rosea" in the pet trade actually are G. porteri.

Habitat

The natural habitat of Grammostola rosea is the desert and scrub regions of Northern Chile, Bolivia, and Argentina. While previously thought to be wanderers in nature, large numbers have been observed living in burrows in their natural habitat. They generally do not burrow in captivity. They are usually active in the evening or night.

Food

This tarantula has a diverse menu including grasshoppers, crickets, moths, beetles, cockroaches, mealworms, small lizards, and mammals. When tarantulas are kept as pets, the best food that can be provided for them are crickets that have been gut loaded on vegetables, as this is the best source of hydrated nutrition for the tarantula.

Reproduction

Grammostola rosea has been bred in captivity for years either for research purposes or for trade and Gurley, R (n.d) states that the females profit from a 'cooling period' of a couple of months preceding the introduction of a male for mating. Once a male has reached sexual maturity he will create a sperm web before he is introduced to the female's terrarium. He will eventually approach the females burrow with caution, tapping and vibrating his legs to attract her out of her shelter. At the opportune moment the male will lunge himself forward and using his hooks he will hold the female's chelicerae, pushing his mate into a vertical position giving him access to the female's epigyne (external genitalia). The male will insert one (or even both left and right) pedipalp into the female's epigyne and inject the fertilizing fluid. Gurley, R (n.d) continues that in the weeks following fertilization, the female produces a large egg sac (usually containing around 500 spiderlings).

Pets

This section is written like a manual or guidebook. Please help rewrite this section from a descriptive, neutral point of view, and remove advice or instruction. (August 2010) (Learn how and when to remove this template message)
Gramostola rosea are relatively docile, low maintenance, and inexpensive, so they are popular as pets. A terrarium should be at least triple the spiders' legspan in length, with a retreat for hiding. Though docile, they can become aggressive if handled too frequently. G. rosea can be kept in relatively low humidity; overflowing the water dish one or two times a week should provide ample humidity for this species. They are quite happy living at temperatures of around 25-30°C (77-86°F), with a diet of four to six crickets every three weeks (or one locust per week). Their feeding schedule is rather erratic, however; the spider can fast for weeks to months at a time. Fasting is sometimes an indication of an upcoming moult.

Grammostola rosea are usually skittish, running away from danger rather than acting defensively, but they may also raise their front legs and present their fangs in preparation to defend themselves. They can act especially defensive for days after moulting; this may be innate in the spiders behavior. As with the majority of tarantulas from the Americas (New World tarantulas), they have small spine-like urticating hairs on their abdomen that they kick off or release when threatened as a defense. Aggressive specimens are often known to have a bald spot on their abdomen from frequent kicking of the hairs, which is often a sign of being over handled.

In February 2009 a British man was treated for tarantula hairs lodged in his cornea. The urticating hairs were thrown from the man's pet G. rosea while the man was cleaning its tank. Medical authorities urge owners to wear protective eyewear when handling a G. rosea.

source - Wikipedia
if u like the post please like and shear

Buthidae is the largest family of scorpions, containing about 80 genera and over 800 species as of mid-2008. Its members are known as, for example, fat-tailed scorpions and bark scorpions. There are a few very large genera (like Ananteris, Centruroides, Compsobuthus or Tityus), but also a high number of species-poor or monotypic ones. New taxa are being described at a rate of several to several dozen new species per year. They occur in the warmer parts of every major landmass on Earth, except on New Zealand. Together with the Microcharmidae, the Buthidae make up the superfamily Buthoidea. The family was established by Carl Ludwig Koch in 1837.

Around 20 species of medically important (meaning potentially lethal to humans) scorpions are known and all but one of these are members of Buthidae. In dead specimens, the spine beneath the stinger, characteristic for this family, can be observed.

List of genera and species

Afghanobuthus Lourenco, 2005
Afroisometrus Kovarik, 1997
Akentrobuthus Lamoral, 1976
Alayotityus Armas, 1973
Ananteris
Androctonus – fattail scorpions
Anomalobuthus
Apistobuthus
Australobuthus
Babycurus
Baloorthochirus
Birulatus
Buthacus
Butheoloides
Butheolus
Buthiscus
Buthoscorpio (includes "Stenochirus" jinnahii and "S." rahmatii)
Buthus
Centruroides – typical bark scorpions
Charmus
Cicileus
Cicileiurus
Compsobuthus
Congobuthus
Darchenia
Egyptobuthus
Grosphus
Hemibuthus
Hemilychas
Himalayotityobuthus
Hoplocystis (a nomen dubium)
Hottentotta
Iranobuthus
Isometrus
Isometroides
Karasbergia
Kraepelinia
Lanzatus
Leiurus
Liobuthus
Lissothus
Lychas
Lychasoides
Mauritanobuthus
Mesobuthus (paraphyletic?)
Mesotityus
Microananteris
Microbuthus
Microtityus
Neobuthus
Neogrosphus
Odontobuthus
Odonturus
Orthochirus
Orthochiroides
Orthochirus (includes Paraorthochirus and Simonoides)
Parabuthus
Pectinibuthus
Physoctonus
Plesiobuthus
Polisius
Psammobuthus
Pseudolissothus
Pseudolychas
Pseudouroplectes
Razianus
Rhopalurus
Sabinebuthus
Sassanidothus
Somalibuthus
Somalicharmus
Thaicharmus
Tityobuthus
Tityopsis
Tityus
Troglorhopalurus
Troglotityobuthus
†Uintascorpio (Eocene, Green River Formation)
Uroplectes
Uroplectoides
Vachoniolus
Vachonus
Zabius
Description

Few Buthidae scorpions are among the larger scorpions; on average the members of this family are mid-sized tending towards smallish. Microtityus and Microbuthus barely reach 2 cm (0.8 in). The largest members are found among Androctonus (fattail scorpions), Apistobuthus, and Centruroides; and can reach a dozen cm (approximately 5 inches). Most of them have between two and five pairs of eyes. Some resemble Vaejovidae. Chaerilidae and Chactidae have one pair of eyes at most, and the former show a yellowish spot between and to the rear of these.

Their vernacular name refers to the thick tails found in many Buthidae, especially in the Old World. The pedipalps on the other hand tend to be weak, slender and tweezer-like. Members of Buthidae are generally rather cryptically colored, quite uniformly ochre to brown, but some are black or (like Centruroides and Uroplectes) more vividly colored. More conspicuous patterns and shapes occur e.g. in Isometrus or Lychas.

Toxicity and relationship with humans

Scorpion § Scorpion sting and venom

A handful of sometimes species-rich genera – fattail scorpions (Androctonus), Centruroides, Hottentotta,[Note 1] Leiurus, Parabuthus and Tityus – are notorious for their strong venom. Human fatalities have been recorded from fewer than two dozen species; identification of e.g. a particular Tityus is likely problematic and detailed data on the venom exists only for a small fraction of the Buthidae (see BmKAEP from the venom of Mesobuthus martensii, for an example).

source - Wikipedia
if u like the post please like and shear

For the spider ranging from southeastern California to Arizona, see desert recluse. For the spider inhabiting Hawaii, see Mediterranean recluse spider.
The brown recluse, Loxosceles reclusa, Sicariidae (formerly placed in a family "Loxoscelidae") is a spider with a necrotic venom and is one of two spiders (the other being the brown widow) with medically significant venom in North America.

Brown recluse spiders are usually between 6 and 20 millimetres (0.24 and 0.79 in), but may grow larger. While typically light to medium brown, they range in color from whitish to dark brown or blackish gray. The cephalothorax and abdomen are not necessarily the same color. These spiders usually have markings on the dorsal side of their cephalothorax, 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 nicknames fiddleback spider, brown fiddler, or violin spider.

Description

The brown recluse.

The brown recluse has three pairs of eyes, unlike most spiders.
The violin pattern is not diagnostic, as other spiders can have similar markings (e.g. cellar spiders and pirate spiders). For definitive identification it is imperative to examine the eyes. While most spiders have eight eyes, recluse spiders have six eyes arranged in pairs (dyads) with one median pair and two lateral pairs. Only a few other spiders have three pairs of eyes arranged in this way (e.g., scytodids). Recluses have no obvious coloration patterns on the abdomen or legs, and the legs lack spines. The abdomen is covered with fine short hairs that, when viewed without magnification, give the appearance of soft fur. The leg joints may appear to be a slightly lighter color.

Life-cycle

Adult brown recluse spiders often live about one to two years. Each female produces several egg sacs over a period of two to three months, from May to July, with approximately fifty eggs in each sac. The eggs hatch in about one month. The spiderlings take about one year to grow to adulthood. The brown recluse spider is resilient and can tolerate up to six months of extreme drought and scarcity or absence of food. On one occasion it survived in controlled captivity for over five seasons without food.

Behavior

A brown recluse's stance on a flat surface is usually with all legs radially extended. When alarmed it may lower its body, withdraw the forward two legs straight rearward into a defensive position, withdraw the rearmost pair of legs into a position for lunging forward, and stand motionless with pedipalps raised. The pedipalps in mature specimens are dark and quite prominent and are normally held horizontally forward. When threatened it usually flees, seemingly to avoid a conflict, and if detained may further avoid contact with quick horizontal rotating movements or even resort to assuming a lifeless pose (playing dead). The spider does not usually jump unless touched brusquely, and even then its avoidance movement is more of a horizontal lunge rather than a vaulting of itself entirely off the surface. When running, the brown recluse does not leave a silk line behind, which would make it more easily tracked when it is being pursued. Movement at virtually any speed is an evenly paced gait with legs extended. When missing a leg or two it appears to favor this same gait, although (presumably when a leg has been injured) it may move and stand at rest with one leg slightly withdrawn. During travel it stops naturally and periodically when renewing its internal hydraulic blood pressure that, like most spiders, it requires to renew strength in its legs.

Habitat

Brown recluse on cardboard box.
Brown recluse spiders build asymmetrical (irregular) webs that frequently include a shelter consisting of disorderly thread. They frequently build their webs in woodpiles and sheds, closets, garages, plenum spaces, cellars, and other places that are dry and generally undisturbed. When dwelling in human residences they seem to favor cardboard, possibly because it mimics the rotting tree bark which they inhabit naturally. They have also been encountered in shoes, inside dressers, in bed sheets of infrequently used beds, in clothes stacked or piled or left lying on the floor, inside work gloves, behind baseboards and pictures, in toilets, and near sources of warmth when ambient temperatures are lower than usual. Human-recluse contact often occurs when such isolated spaces are disturbed and the spider feels threatened. Unlike most web weavers, they leave these lairs at night to hunt. Males move around more when hunting than the females, which tend to remain nearer to their webs. The spider will hunt for firebrats, crickets, cockroaches, and other soft-bodied insects.[citation needed]

Distribution

A large brown recluse compared to a US penny (diameter 0.75 inches, 19.05mm)
The range lies roughly south of a line from southeastern Nebraska through southern Iowa, Illinois, and Indiana to southwestern Ohio. In the southern states, it is native from central Texas to western Georgia and north to Kentucky.

Despite rumors to the contrary, the brown recluse spider has not established itself in California or anywhere outside its native range. This directly contradicts numerous sensationalized media reports of bites occurring where these spiders are absent (and no specimens were found), such as a 2014 report from Thailand, where a man was claimed to have died from a brown recluse bite. Over the last century, occasional spiders have been intercepted in various locations where they have no known established populations; these spiders may be transported fairly easily, though the lack of established populations well outside the natural range also indicates that such movement has not led to colonization of new areas, after decades of opportunities. Note that the occurrence of brown recluses in a single building (such as a warehouse) outside of the native range is not considered a successful colonization; such single-building populations can occur (e.g., in several such cases in Florida), but do not spread, and can be easily eradicated.

There are other species of the genus Loxosceles native to the southwestern part of the United States, including California, that may resemble the brown recluse, but these species have never been documented as medically significant. The number of "false positive" reports based on misidentifications is considerable; in a nationwide study where people submitted spiders that they thought were brown recluses, of 581 from California only 1 was a brown recluse—submitted by a family that moved from Missouri and brought it with them (compared to specimens submitted from Missouri, Kansas, and Oklahoma, where between 75% and 90% were recluses). From this study, the most common spider submitted from California as a brown recluse was in the genus Titiotus, whose bite is deemed harmless. A similar study documented that various arachnids were routinely misidentified by physicians, pest control operators, and other non-expert authorities, who told their patients or clients that the spider they had was a brown recluse when in fact it was not. Despite the absence of brown recluses from the Western U.S., physicians in the region commonly diagnose "brown recluse bites", leading to the popular misconception that the spiders inhabit those areas.

Bite

Loxoscelism

The bite frequently is not felt initially and may not be immediately painful, but it can be serious. The brown recluse bears a potentially deadly hemotoxic venom. Most bites are minor with no necrosis. However, a small number of brown recluse bites do produce severe dermonecrotic lesions (i.e. necrosis); an even smaller number produce severe cutaneous (skin) or viscerocutaneous (systemic) symptoms. In one study of clinically diagnosed brown recluse bites, skin necrosis occurred 37% of the time, while systemic illness occurred 14% of the time. In these cases, the bites produced a range of symptoms common to many members of the Loxosceles genus known as loxoscelism, which may be cutaneous and viscerocutaneous. In very rare cases, bites can even cause hemolysis—the bursting of red blood cells.

As suggested by its specific epithet reclusa (recluse), the brown recluse spider is rarely aggressive, and bites from the species are uncommon. In 2001, more than 2,000 brown recluse spiders were removed from a heavily infested home in Kansas, yet the four residents who had lived there for years were never harmed by the spiders, despite many encounters with them. The spider usually bites only when pressed against the skin, such as when tangled within clothes, towels, bedding, inside work gloves, etc. Many human victims report having been bitten after putting on clothes that had not been worn recently, or had been left for many days undisturbed on the floor. The fangs of the brown recluse are so tiny they are unable to penetrate most fabric.

Around 49% of brown recluse bites do not result in necrosis or systemic effects. When both types of loxoscelism do result, systemic effects may occur before necrosis, as the venom spreads throughout the body in minutes. Children, the elderly, and the debilitatingly ill may be more susceptible to systemic loxoscelism. The systemic symptoms most commonly experienced include nausea, vomiting, fever, rashes, and muscle and joint pain. Rarely, such bites can result in hemolysis, thrombocytopenia, disseminated intravascular coagulation, organ damage, and even death. Most fatalities are in children under the age of seven or those with a weak immune system.

While the majority of brown recluse spider bites do not result in any symptoms, cutaneous symptoms occur more frequently than systemic symptoms. In such instances, the bite forms a necrotizing ulcer that destroys soft tissue and may take months to heal, leaving deep scars. These bites usually become painful and itchy within 2 to 8 hours. Pain and other local effects worsen 12 to 36 hours after the bite, and the necrosis develops over the next few days. Over time, the wound may grow to as large as 25 cm (10 inches). The damaged tissue becomes gangrenous and eventually sloughs away.

There is now an ELISA-based test for brown recluse venom that can determine whether a wound is a brown recluse bite, although it is not commercially available and not in routine clinical use. Clinical diagnoses often use Occam's razor principle in diagnosing bites based on what spiders the patient likely encountered and previous similar diagnoses.

There are numerous documented infectious and noninfectious conditions that produce wounds that have been initially misdiagnosed as recluse bites by medical professionals, including:

Pyoderma gangrenosum
Infection by Staphylococcus
Infection by Streptococcus
Herpes
Diabetic ulcers
Fungal infection
Chemical burns
Toxicodendron dermatitis
Squamous cell carcinoma
Localized vasculitis
Syphilis
Toxic epidermal necrolysis
Sporotrichosis
Lyme disease
Many of these conditions are far more common and more likely to be the source of necrotic wounds, even in areas where brown recluse spiders actually occur. The most important of these is methicillin-resistant Staphylococcus aureus (MRSA), a bacterium whose necrotic lesions are very similar to those induced by recluse bites, and which can be lethal if left untreated. Misdiagnosis of MRSA as spider bites is extremely common (nearly 30% of patients with MRSA reported that they initially suspected a spider bite), and can have fatal consequences.

Reported cases of brown recluse bites occur primarily in Arkansas, Colorado, Kansas, Missouri, Nebraska, Oklahoma, and Texas. There have been many reports of brown recluse bites in California—though a few related species may be found there, none of these are known to bite humans. To date, the reports of bites from areas outside of the spider's native range have been either unverified, or, if verified, the spiders have been moved to those locations by travelers or commerce. Many arachnologists believe that a large number of bites attributed to the brown recluse in the West Coast are either from other spider species or not spider bites at all. For example, the venom of the hobo spider, a common European species established in the northwestern United States and southern British Columbia, has been reported to produce similar symptoms as the brown recluse bite when injected into laboratory rabbits. However, the toxicity of hobo spider venom has been called into question as actual bites have not been shown to cause necrosis, and no such occurrences have ever been reported where the spider is native.

Numerous other spiders have been associated with necrotic bites in medical literature. Other recluse species, such as the desert recluse (found in the deserts of southwestern United States), are reported to have caused necrotic bite wounds, though only rarely. The hobo spider and the yellow sac spider have also been reported to cause necrotic bites. However, the bites from these spiders are not known to produce the severe symptoms that can follow from a recluse spider bite, and the level of danger posed by these has been called into question. So far, no known necrotoxins have been isolated from the venom of any of these spiders, and some arachnologists have disputed the accuracy of spider identifications carried out by bite victims, family members, medical responders, and other non-experts in arachnology. There have been several studies questioning the danger posed by some of these spiders. In these studies, scientists examined case studies of bites in which the spider in question was identified by an expert, and found that the incidence of necrotic injury diminished significantly when "questionable" identifications were excluded from the sample set. (For a comparison of the toxicity of several kinds of spider bites, see the list of spiders having medically significant venom.)

First aid involves the application of an ice pack to control inflammation 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.

Routine treatment should include immobilization of the affected limb, application of ice, local wound care, and tetanus prophylaxis. Many other therapies have been used with varying degrees of success, including hyperbaric oxygen, dapsone, antihistamines (e.g., cyproheptadine), antibiotics, dextran, glucocorticoids, vasodilators, heparin, nitroglycerin, electric shock, curettage, surgical excision, and antivenom. None of these treatments have been subjected to randomized controlled trials to conclusively show benefit. In almost all cases, bites are self-limited and typically heal without any medical intervention.

Outpatient palliative care following discharge often consists of a weak or moderate strength opioid (e.g. codeine or tramadol, respectively) depending on pain scores, an anti-inflammatory agent (e.g. naproxen, cortisone), and an antispasmodic (e.g. cyclobenzaprine, diazepam), for a few days to a week. If the pain and/or spasms have not resolved by this time, a second medical evaluation is generally advised, and differential diagnoses may be considered. Occasionally, an antibiotic is prescribed as well.

Cases of brown recluse venom travelling along a limb through a vein or artery are rare, but the resulting tissue mortification can affect an area as large as several inches and in extreme cases require excising of the wound.

In presumed cases of recluse bites, dapsone is often used for the treatment of necrosis, but controlled clinical trials have yet to demonstrate efficacy. However, dapsone may be effective in treating many "spider bites" because many such cases are actually misdiagnosed microbial infections. There have been conflicting reports about its efficacy in treating brown recluse bites, and some have suggested it should no longer be used routinely, if at all.

Wound infection is rare. Antibiotics are not recommended unless there is a credible diagnosis of infection.

Studies have shown that surgical intervention is ineffective and may worsen outcome. Excision may delay wound healing, cause abscesses, and lead to scarring.

Purportedly application of nitroglycerin stopped necrosis. However, one scientific animal study found no benefit in preventing necrosis, with the study's results showing it increased inflammation and caused symptoms of systemic envenoming. The authors concluded the results of the study did not support the use of topical nitroglycerin in brown recluse envenoming.

Antivenom is available in South America for the venom of related species of recluse spiders. However, the bites, often being painless, usually do not present symptoms until 24 or more hours after the event, possibly limiting the effect of this intervention.

Due to increased fear of these spiders prompted by greater public awareness of their presence in recent years, extermination of domestic brown recluses is performed frequently in the lower midwestern United States. Brown recluse spiders possess a variety of adaptive abilities, including the ability to maintain homeostasis for several seasons with no food or water. Additionally, these spiders survive significantly longer in a relatively cool, thermally stable environment.

The most important precaution is to remove and reduce trash and rubbish from your property, such as woodpiles, boxes, plywood, tires, and trash cans—especially if they are stored right next to the house. With attached garages, block off house access by sealing cracks around doors and access holes for electrical conduits or plumbing. In the Midwest, some brown recluse bites occur when a sleeping person rolls over during the night, and the trapped spider bites. In the bedroom, move the bed away from the wall, remove any skirts or ruffles and remove all items stored under it. This minimizes chances that any spider can crawl onto the bed. Do not leave clothes and shoes on the floor, or shake them before dressing if they are left out. Apparel and equipment that is only occasionally worn should be stored in tightly closed plastic bags, especially if stored in the garage or other dark storage areas. Typically, pesticide control of spiders is difficult. There are various insecticides available in retail outlets labeled for spider control. However, spiders' perched legs allow them to walk over most pesticides, making the use of chemicals to eradicate the spiders impractical and unnecessarily toxic. A 2014 study indicates that fumigation may be more effective than previously believed. Sticky traps placed along floor boards offer a non-insecticidal way to trap spiders as well as provide an idea of population levels in the structure.

source - Wikipedia
if u like the post please like and shear

>
Phoneutria, commonly known as Brazilian wandering spiders, armed spiders (armadeiras, as they are known in Brazilian Portuguese), or banana spiders (a name shared with several others), are a genus of aggressive and venomous spiders of potential medical significance to humans. They are mainly found in tropical South America, with one species in Central America. These spiders are members of the family Ctenidae of wandering spiders.

The Brazilian wandering spiders appear in Guinness World Records from 2010 as the world's most venomous spider. Guinness World Records states that although the Brazilian wandering spider venom is the most toxic, an effective antivenom is available and few fatalities occur.

Description

The spiders in the genus can grow to have a leg span of 13 to 15 cm (5.1 to 5.9 in). Their body length ranges from 17 to 48 mm (0.67 to 1.89 in). While some other araneomorph spiders have a longer leg span, the largest Phoneutria species have the longest body and the greatest body weight in this group. The genus is distinguished from other related genera such as Ctenus by the presence of dense prolateral scopulae (a dense brush of fine hairs) on the pedipalp tibiae and tarsi in both sexes. Phoneutria are easily confused with several other non-medically significant ctenids, especially Cupiennius, in which the recently described C. chiapanensis also has bright red hairs on the chelicerae. Additionally, some Phoneutria species lack red hairs on the chelicerae, making it an unreliable identification feature. The presence of a dark linear stripe or stripes on the frontal (dorsal) palps and presence of a single thin black line running anterior-posterior along the dorsal carapace may help identify Phoneutria. Other features are the strong ventral marking on the underside of the legs with contrasting dark mid-segments and lighter joints, and the pattern on the ventral (underside) of the abdomen with several rows of black dots, or an overall reddish colour.

The characteristic defensive posture with frontal legs held high is an especially good indicator to confirm a specimen is Phoneutria, especially alongside correct colour patterns. During the defensive display the body is lifted up into an erect position, the first two pairs of legs are lifted high (revealing the conspicuous black/light-banded pattern on the leg underside), while the spider sways from side to side with hind legs in a cocked position.

Taxonomy

The genus Phoneutria was erected by Maximilian Perty in 1833. The genus name is from the Greek φονεύτρια, meaning "murderess". Perty placed two species in the genus: Phoneutria rufibarbis and Phoneutria fera. The former is treated as a "doubtful name" (nomen dubium); the latter as the type species of the genus.

Female of P. cf nigriventer. This and other species of the genus Phoneutria have medically significant venom that can be dangerous if the spiders are handled.
As of March 2016, the World Spider Catalog accepted the following species:

Phoneutria bahiensis Simó & Brescovit, 2001 – Brazil
Phoneutria boliviensis (F. O. Pickard-Cambridge, 1897) – Central, South America
Phoneutria eickstedtae Martins & Bertani, 2007 – Brazil
Phoneutria fera Perty, 1833 (type species) – Colombia, Ecuador, Peru, Brazil, Suriname, Guyana
Phoneutria keyserlingi (F. O. Pickard-Cambridge, 1897) – Brazil
Phoneutria nigriventer (Keyserling, 1891) – Brazil, Uruguay, Paraguay, Argentina
Phoneutria pertyi (F. O. Pickard-Cambridge, 1897) – Brazil
Phoneutria reidyi (F. O. Pickard-Cambridge, 1897) – Colombia, Venezuela, Peru, Brazil, Guyana
^ a b c "Gen. Phoneutria Perty, 1833", World Spider Catalog, Natural History Museum Bern, retrieved 2016-03-14
^ a b
^ Wandering Spiders of the Amazon (2013). Phoneutria - toxicity. Staatliches Museum für Naturkunde Karlsruhe (State Museum of Natural History Karlsruhe). Retrieved 23 February 2013.
Species

Female of P. cf nigriventer. This and other species of the genus Phoneutria have medically significant venom that can be dangerous if the spiders are handled.
As of March 2016, the World Spider Catalog accepted the following species:

Phoneutria bahiensis Simó & Brescovit, 2001 – Brazil
Phoneutria boliviensis (F. O. Pickard-Cambridge, 1897) – Central, South America
Phoneutria eickstedtae Martins & Bertani, 2007 – Brazil
Phoneutria fera Perty, 1833 (type species) – Colombia, Ecuador, Peru, Brazil, Suriname, Guyana
Phoneutria keyserlingi (F. O. Pickard-Cambridge, 1897) – Brazil
Phoneutria nigriventer (Keyserling, 1891) – Brazil, Uruguay, Paraguay, Argentina
Phoneutria pertyi (F. O. Pickard-Cambridge, 1897) – Brazil
Phoneutria reidyi (F. O. Pickard-Cambridge, 1897) – Colombia, Venezuela, Peru, Brazil, Guyana
^ Wandering Spiders of the Amazon (2013). Phoneutria - toxicity. Staatliches Museum für Naturkunde Karlsruhe (State Museum of Natural History Karlsruhe). Retrieved 23 February 2013.
^ "Gen. Phoneutria Perty, 1833", World Spider Catalog, Natural History Museum Bern, retrieved 2016-03-14
Behaviour

Wandering spiders are so-called because they wander the jungle floor at night, rather than residing in a lair or maintaining a web. During the day they hide inside termite mounds, under fallen logs and rocks, and in banana plants (hence the "banana spider" nickname) and bromeliads. P. nigriventer is known to hide in dark and moist places in or near human dwellings.

P. nigriventer mates during the dry season from April to June, which leads to frequent observations of the species during this time.

Distribution

Phoneutria are found in forests from Costa Rica, and throughout South America east of the Andes into northern Argentina, including Colombia, Venezuela, the Guianas, Ecuador, Peru, Bolivia, Brazil and Paraguay. Three species (P. reidyi, P. boliviensis and P. fera) are found in the Amazon region, one species (P. fera) is restricted to the Amazon, and one (P. boliviensis) ranges into Central America in Panama and Costa Rica. The remaining species are restricted to Atlantic Forest of Argentina, Paraguay and Brazil, including forest fragments in the Cerrado savanna. In Brazil, Phoneutria is only absent in the northeastern region north of Salvador, Bahia.

Phoneutria has been introduced to Chile and Uruguay.

Toxicity and prey

P. fera and P. nigriventer are widely considered the most venomous species of spider. Their venom contains a potent neurotoxin, known as PhTx3, which acts as a broad-spectrum calcium channel blocker that inhibits glutamate release, calcium uptake and also glutamate uptake in neural synapses. At deadly concentrations, this neurotoxin causes loss of muscle control and breathing problems, resulting in paralysis and eventual asphyxiation. In addition, the venom causes intense pain and inflammation following a bite due to an excitatory effect the venom has on the serotonin 5-HT4 receptors of sensory nerves. This sensory nerve stimulation causes a release of neuropeptides such as substance P which triggers inflammation and pain. The median lethal dose (LD50) of the venom is 134 µg/kg.

Aside from causing intense pain, the venom of the spider can also cause priapism in humans. Erections resulting from the bite are uncomfortable, can last for many hours and can lead to impotence. A component of the venom (Tx2-6) is being studied for use in erectile dysfunction treatments.

The amount of P. nigriventer venom necessary to kill a 20 g mouse has been shown to be only 6 μg intravenously and 134 μg subcutaneously as compared to 110 μg and 200 μg respectively for Latrodectus mactans (Southern black widow). This ranks Phoneutria venom among the most deadly spider venoms to mice. The Brazilian wandering spider's prey also includes crickets, katydids, mantids, and other larger animals, including tree frogs and lizards.

Danger to humans

The genus Phoneutria includes some of the relatively few species of spiders known to present a threat to humans. Danger to humans is not merely a question of toxicity, but requires the capacity to deliver the venom, a sufficient quantity of venom, a disposition that makes a bite likely and proximity to human habitation. The actual incidence of death or serious injury must also be considered.

Spider mouthparts are adapted to envenom very small prey; they are not well-adapted to attacking large mammals such as humans. Some experts believe that various spiders like Phoneutria can deliver a "dry" bite to purposely conserve their venom, as opposed to a more primitive spider like Atrax that usually delivers a full load.[citation needed] A study in March 2009 suggests that Phoneutria inject venom in approximately one-third of their bites, and only a small quantity in one-third of those cases. Another study similarly suggested that only 2.3 percent of bites (mainly in children) were serious enough to require antivenom. Other studies, as cited in the Wolfgang Bücherl studies, showed that the toxicity of Phoneutria venom was clearly more potent than both Latrodectus and Atrax. Research in this area is hindered by the difficulty of identifying particular species. Nevertheless, there are well-attested instances of death. In one case, a single spider killed two children in São Sebastião. The spider was positively identified as a Phoneutria by Wolfgang Bücherl.

Despite their reputation as the world's deadliest spiders, there are multiple studies that call into question their capacity for fatal human envenomation, though some of these are labeled with a level of uncertainty, as Phoneutria are often confused with other genera of ctenids, lycosids or other large labidognatha spiders. Of the eight described species, P. nigriventer and P. fera most frequently receive mention in mass-media publications. P. nigriventer is the species responsible for most cases of venom intoxication in Brazil because it is commonly found in highly populated areas of southeastern Brazil, such as the states of São Paulo, Minas Gerais, Rio de Janeiro and Espírito Santo. The species P. fera is native to the northern portion of South America in the Amazon of Brazil, Venezuela, Ecuador, Peru and the Guyanas.

These spiders' wandering nature is another reason they are considered so dangerous. In densely populated areas, Phoneutria species usually search for cover and dark places to hide during daytime, leading it to hide within houses, clothes, cars, boots, boxes and log piles, where they may bite if accidentally disturbed. These spiders acquired their other common name, "banana spider", because they are occasionally found within shipments of bananas, though the number of reports is exaggerated due to common misidentifications of unrelated spiders; a survey of spiders found in banana shipments revealed that only 7 of 135 spiders were Phoneutria species, and spiders such as Cupiennius had been misidentified by otherwise experienced arachnologists. Nonetheless, real cases have been documented: in 2005 a man was bitten in Bridgwater, England by a P. fera in a shipment of bananas; he was quickly treated but took a week to recover. In 2014 a family in London found and photographed a Brazilian wandering spider in a bunch of bananas delivered to their home.

source - Wikipedia
if u like the post please like and shear

Pages

The book of earth

Toxicity and relationship with humans

Scorpion § Scorpion sting and venom

Loxoscelism

Translate

About Me

LET’S BE FRIENDS

Popular Posts

Labels

recent posts

Blog Archive