MODIFICATIONS OF THE FOOD PUMPS OF HYDROCORISAE (HETEROPTERA)

Abstract

The food pumps of ninny Hydrocorisae contain devices for straining or masticating ingested foods. In the Belostomatidae and Nepidae these consist of minute, sclerotized processes on the anteclypeal epipharynx. The cibarial dilator muscles are not subdivided, and the anteclypeus is unmodified. The Gelastocoridae, Ochteridae, Notonectidae, and Naucoridae have more complex epipharyngeal and hypopharyugeal devices (ridges, folds, hairs, or "teeth") in their tripartite, cibarial pumps. Their cibarial muscles are subdivided into four groups, and their anteclypei are anteriorly broadened and fused with the loral plates. The grinding and filtering devices of the Corixidae are very elaborate. Their food pumps are bipartite and controlled by both pharyngeal and cibarial muscles, the latter being divided into two groups. The corixid anteclypeus is broadened but not fused with the loral plates.These masticating or straining devices appear to be specialized rather than primitive features. It is proposed that they arose independently at least twice and possibly three times in the Hydrocorisae. It is also suggested that the ancestral Hydrocorisae gave rise first to the Belostomatidae and Nepidae, then to the Corixidae, still later to the Gelastocoridae and Ochteridae, and finally to the Notonectidae and Naucoridae.