Wikipedia
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.