acidopore

A small circular opening or orifice at the tip of the gaster used to expel formic acid as part of the defensive and communication system. When present the acidopore is generally surrounded by a fringe of short hairs or setae and is easily seen. In a few species the fringe of hairs is lacking and the acidopore can be difficult to detect. This structure is found only in the subfamily Formicinae and occurs in all genera within this subfamily (Shattuck, 1994).

gaster armed with acidopore (Paratrechina longicornis)