ant mimic spider or velvet ant mimic spider or ground spider

Description:

This spider came crawling across my coworkers desk. It is about the size of a large grain of rice and resembles an ant in its shape and the way it moves. It has a relatively long orange cephalothorax and a black or gray abdomen with three white bands across it's back from side to side (like a bee). It has relatively large mandibles for its size, shaped like boxing gloves below its head. It seems to have four spinnerets.