Rachiptera limbata Bigot develops on Baccharis linearis (R. et Pav.) in the areas around Santiago, Chile. The larvae feed on stem tissues and secrete a liquid that hardens to form a protective feeding and pupation chamber. The immature stages of Neotropical species of Tephritinae are poorly known. In this paper, the morphology of the immature stages of R. limbata are described and compared, in a phylogenetic context, with other Tephritinae species. Antennomaxillary complex, pads, oral ridge, cephalopharyngeal skeleton, anterior and posterior spiracles and anal lobes of first-, second-, third-instar larvae and pupae were studied with optical and scanning electron microscopy. The cephalopharyngeal skeleton is darkly sclerotized and shows an opening or window in the ventral cornua. This trait seems to be plesiomorphic in R. limbata and in other Neotropical species. First-instar larvae anterior spiracles are absent; whereas in second and third instars spiracles are developed as a row of five short tubules. In first- and second-instar larvae, the posterior spiracular slit has only a single hair per bundle; whereas third-instar larvae lack hairs. This last trait seems to be consequence of a larval development delay and an apomorphic trait in R. limbata, compared to other Neotropical and Neartical species.
Adaptation; neoteny; plesiomorphic; apomorphic traits
