Myth: A deadly, exotic spider has been found lurking under toilet seats in airports and airplanes.
Fact: This urban legend began in August, 1999 as a deliberate Internet hoax, disguised as a news story. The original version refers to a spider allegedly called Arachnius gluteus, or South American Blush Spider (literally "butt spider"). Nothing mentioned in the story is genuine; there is no such spider, no such airport, no such medical association, no such doctor, no such restaurant, and no such aeronautics board. For more detail, see Rick Vetter's hoax page.
In October, 2002 a new version of the same hoax surfaced. This one mentions a real species, the south Asian jumping spider, Telamonia dimidiata, but it is still a hoax. A jumping spider is one of the least likely to be found in such a situation; they are sun-lovers, and none are more than mildly toxic to humans. This version resurfaced in 2011.