Latrodectus

noun

Lat·​ro·​dec·​tus -ˈdek-təs 

: a genus of nearly cosmopolitan spiders of the family Theridiidae that includes most of the well-known venomous spiders (as the black widow, L. mactans), that are of medium size and dark or black in color and often marked with red, and that have a large globular usually glossy abdomen and long and wiry legs