Ovoviviparity and morphology of the female reproductive system in Palumbina (Lepidoptera, Gelechiidae, Thiotrichinae)

Abstract Ovoviviparity is reported for the genus Palumbina of Thiotrichinae. The females of eight species were found to retain a hatched first instar larva or a fully developed embryo in the oviduct (vestibulum), which suggests that the females may deposit larvae or mature eggs that are ready to hatch. In the mature embryos, the mandibles and a head capsule were visible and enclosed in chorion. Taking this into consideration, the embryos may contain sufficient nutrition for development within the eggshell, which indicates an ovoviviparous reproduction. The embryos in the oviduct were not dissolved while the early-stage embryos in the anterior portion of the abdomen were destroyed by the treatment of KOH. Therefore, the formation of chorion likely takes place in the oviduct. The female reproductive system of Palumbina displayed typical morphology of ditrysian Lepidoptera although it showed minor variations among the species. The paired reservoirs of the colleterial gland were rather reduced in the species that carried larvae. We assume that this might be related to the ovoviviparous reproductive physiology. The lagena of the spermatheca was present or absent, and if present, the shape and the size were various even in the same species. The species without lagena had a numerous thorn-like structures on the utriculus. The function is possibly related to the maintenance of sperm, but the correlation between the structure and the absence of the lagena remains unclear. Further detailed studies are required to reveal the comprehensive mechanism of the ovoviviparous reproduction in Palumbina .