Postembryonic development of the ground louse Zorotypus caudelli Karny (Insecta: Zoraptera: Zorotypidae)

Abstract

Based on captive breeding, the postembryonic development of the ground louse Zorotypus caudelli Karny, 1927 (Zoraptera, Zorotypidae) was examined and described in detail. The number of nymphal instars in Z. caudelli is five. During the second molt (2nd to 3rd instar), the number of antennomeres increases from eight to nine by subdivision of the basal flagellomere (meriston). Apterous and winged forms differentiate in the 4th nymphal instar. In the 4th instar of the winged form, small wing pads and small ocular spots appear. In the 5th instar, the wing pads elongate and the ocular spots are widened, and three ocelli are differentiated. Wing dimorphism may be a phenomenon independent of crowding. The two sexes closely resemble each other as in other zorapteran species, and sexual dimorphism does not appear until the final (5th) nymphal instar: in the 5th instar of males, setae increase in number on the 9th and 10 + 11th abdominal terga, and a small posteromedian swelling appears on the 10 + 11th abdominal tergum, the precursor of the mating hook. Key to nymphal instars of Zorotypus caudelli was given. The formation of thoracic pleural sclerites was examined and revaluated.