''Trechona venosa'' is a species of a

venomous Venom or zootoxin is a type of toxin produced by an animal that is actively delivered through a wound by means of a bite, sting, or similar action. The toxin is delivered through a specially evolved ''venom apparatus'', such as fangs or a sti ...

spider Spiders ( order Araneae) are air-breathing arthropods that have eight legs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species ...

edemic to

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

Description and behavior

''Trechona venosa'' is a large South American

mygalomorphae The Mygalomorphae, or mygalomorphs, are an infraorder of spiders, and comprise one of three major groups of living spiders with over 3000 species, found on all continents except Antarctica. Many members are known as trapdoor spiders due to the ...

, they grow from 3 to 4.5 in length (1.2–1.8 inches). In wingspan, they can grow from 6 to 7 cm, equivalent to 2.4–2.8 inches respectively, while the fangs measure 3–4 mm in length. Its color is black or brownish-gray, with yellow stripes on the abdomen. ''Trechona venosa'' is not an aggressive spider, inhabiting plants in the tropical forests of the

Atlantic Forest The Atlantic Forest ( pt, Mata Atlântica) is a South American forest that extends along the Atlantic coast of Brazil from Rio Grande do Norte state in the northeast to Rio Grande do Sul state in the south and inland as far as Paraguay and th ...

. They live on the edges of forests in places far from housing and human activity. They have

nocturnal Nocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnal meaning the opposite. Nocturnal creatures generally have highly developed sens ...

/twilight habits, they are solitary animals, meeting members of their species only during the mating season. They weave funnel-shaped webs.http://repositorio.unicamp.br/jspui/bitstream/REPOSIP/314604/1/Fontana_MarcosDias_D.pdf

Distribution

These spiders are restricted to the Atlantic Forest of

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

Venom

The venom of ''Trechona venosa'' has a lethal dose of 0.070 mg for 20 grams rat by subcutaneous injection, and 0.030 mg by intravenous injection, 2 mg by intramuscular injection results in muscle contractions, paralysis and death in rats, while 0.4 mg results in death by tetanism, for pigeons, the lethal dose ranges from 0.01–0.007 mg, by intravenous injection. The average yield is 1.00 mg, and the maximum is 1.70 mg. Symptoms in mice include severe pain, tremors, salivation, urine output, paroxysmal tetany, spasmodic breathing movements and coma. Symptoms in humans are not known, as accidents are extremely rare, but symptomatic envenoming is possible.

References

{{Taxonbar, from=Q2320066 Spiders of South America Fauna of Brazil Spiders described in 1832