Ontogenesis of pleuropodia in different species of Blattaria (Insecta): A comparative study

Abstract The embryonic development of several insects is characterized by the formation of a pair of pleuropodial appendages on the first abdominal segment. The present paper describes the comparative ontogenesis, morphology, and structure of the pleuropodia of a few species of Blattaria belonging to their three differe/it families: Blattidae, Blattellidae, and Blaberidae. The pleuropodia appear when the first abdominal coelomic cavities begin to disintegrate; then they develop quickly, and regress when the dorsal closure of the embryo occurs. A slow process of degeneration leads, in some species, to the formation of a pair of small flaps; in others, the pleuropodial morphology is retained although the organ loses its secretory functions. In all species, the pleuropodia are cast off at embryonic eclosion, together with the first cuticle produced during an intraoothecal moult. The pleuropodia can be bulbiform, filiform, or caliciform. A relationship is suggested between pleuropodial morphology and the moda...