Description
Acanthosomatidae have heads that are keeled laterally and possess a pair of five-segmented antennae. The mesosternum has a strongly projecting keel. The tarsi of the legs are bisegmented. The second visible abdominal sternite has an elongate spine that projects forwards. The spiracles of the second abdominal segment are concealed by the metapleura. Abdominal sternite III has paired trichobothria. In males, sternite VIII is exposed and there is a specialised genital capsule. In females, one or two pairs of Pendergrast’s organs are present in the abdomen (sometimes absent, e.g. Elasmucha) and sternite VII has an emarginate posterior margin. In general appearance, Acanthosomatidae are similar to Pentatomidae. Various sources distinguish them based on the number of tarsal segments being two in acanthosomatids and three in pentatomids. However, some pentatomids have bisegmented tarsi as well.
