On the spiracles of the larvae of the suborder Myxophaga (Coleoptera)

Abstract

The structure of the spiracles in larvae of three (Hydroscaphidae, Sphaeriidae, Torridincolidae) of the four known families of the suborder Myxophaga is described. Further evidence that supports the validity of the suborder Myxophaga is provided by the unusual nature of the respiratory systems of the three families. The larvae of all three families have spiracular gills, and they are the only endopterygote larvae so far known with such structures. The type of permanent physical gill known as a plastron is widely distributed among adult, pupal, and egg stages of insects. It is here reported for the first time in a larval insect. The spiracular gills of the Torridincolidae support a typical plastron meshwork, and reasons are given for believing that the larvae of the Hydroscaphidae and Sphaeriidae are also plastron-breathers.