Abdomen
Description:
With the head and the thorax, the third major division (tagma) of an insect body. It contains most or all of the systems of digestion and reproduction. In ants, the abdomen is formed by seven visible abdominal segments (A1 to A7) and some of them are highly modified. The first abdominal segment (A1), represented only by its tergite (the sternite has been lost during the Apocrita evolution), is called the propodeum and is incorporated into the thorax to form the alitrunk or mesosoma. The second abdominal segment (A2), the petiole, is usually reduced, forming a node or scale isolated from the alitrunk anteriorly and from the remaining abdominal segments posteriorly. The third abdominal segment (A3) is either reduced and isolated, or not. When reduced and isolated, it is called the postpetiole and the next abdominal segment is the first gastral segment. When it is not reduced and isolated, it is called the first gastral segment and form with the 4 remaining abdominal segments the gaster.
