The food pump of Aphelocheirus aestivalis F. as compared with that of typical Naucoridae (Heteroptera)

The heteropteran cibarium forms a sucking pump which conveys fluid foods into the pharynx. The food pumps of Hydrocorisae have the additional function of grinding or filtering particulate matter; they contain ridges, hairs, and sclerotized processes which have probably evolved at least twice among the hydrocorisine families. Aphelocheirus , like the Naucoridae, possesses a modified anteclypeus and a tripartite type of food pump. The main sucking action occurs in the pump's anterior and posterior regions, while the middle region is specialized for grinding and filtering. The anteclypeus has broadened and fused with other parts of the cranium, and is thus braced against the pull of the powerful cibarial dilator muscles. In the Naucoridae the three regions of the pump have the same functions as those of Aphelocheirus . The pumps of the five naucorid genera here studied are structurally very similar to each other but differ considerably from that of Aphelocheirus . Cibarial morphology, as well as respiratory differences, thus supports the contention that Aphelocheirus is not a member of the Naucoridae but should be placed in a separate family.