Photo by Terry Hayes

Ant-mimicking jumping spider (Synemosyna formica) is often overlooked and mistaken for an ant. It is found in bushes and tall grass from Vermont to Georgia west to Minnesota and Texas.

Most jumping spiders have furry round bodies. Ant-mimicking jumping spider is a Batesian mimic, evolved to imitate the appearance of ants which are avoided by ants, mantises, and larger jumping spiders. The ant-like modifications include a constricted abdomen and front legs that are curved, mimicking ant antennae.

There are more than 300 species of spiders that are ant mimics. Ant-mimicking jumping spider is distinguished by a sharp downward slope between the head portion and the thorax portion of the cephalothorax; narrow, parallel-sided rear portion of the cephalothorax; white or pale marks at the abdominal constriction; and in the palpal bulbs of the male the embolus is fixed to the tegulum.

http://minnesotaseasons.com/Arachnids/ant-mimicking_jumping_spider.html