Latrodectus

Latrodectus is a genus of spider in the big spider family Theridiidae, most of which are commonly known as widow spiders. The genus contains 31 recognized species distributed worldwide, including the North American black widows (L. mactans, L. hesperus, and L. variolus), the button spiders of Africa, and the Australian redback. Species vary widely in size. In most cases the females are dark-colored and readily identifiable by reddish hourglass-shaped markings on the abdomen.