Wikipedia
Missulena is a genus of spiders in the mygalomorph family Actinopodidae, sometimes called mouse spiders. there are 17 known species in this genus, all but one of which are indigenous to Australia. One species, M. tussulena, is found in Chile. The name derives from an old belief, now known to be false, that the spiders dig deep burrows similar to those of mice.
There is evidence that the bite of a mouse spider is potentially as serious as that of an Australasian funnel-web spider; however, recorded envenomings by this spider are rare. Funnel-web antivenom has been found to be an effective treatment for serious bites.
Another spider, Scotophaeus blackwalli, shares the nickname "mouse spider", but does not belong to the genus Missulena and is not considered dangerous.