Anuroctonus phaiodactylus (Swollen Stinger Scorpion)
The Eastern Swollenstinger scorpion (Anuroctonus phaiodactylus) is a nocturnal arachnid found in arid environments, known for its robust pedipalps (claws) and a swollen area just before its stinger on the tail. It's an ambush predator, primarily feeding on insects near its burrow. Stings can cause pain and swelling, but are not typically considered dangerous. 
Key Characteristics:
Appearance: Dark brown, with large, black-tipped claws (pedipalps) and a noticeably swollen region on the tail near the stinger. 
Behavior: Nocturnal, spends most of its time in burrows, and is an ambush predator. 
Habitat: Arid regions, especially in the western United States. 
Venom: Stings can be painful and cause localized swelling, but are not generally considered dangerous to humans, according to Orkin. 
Additional Information:
Diet: Primarily insects and other small invertebrates. 
Life Cycle: Scorpions typically go through several molts before reaching adulthood. 
Defense: Primarily uses its stinger to subdue prey and defends itself when threatened, according to Picture Insect. 
Distinguishing Feature: The swollen area just before the stinger is most prominent in mature males.