Comparative morphology of the larval mouthparts among six species of Notodontidae (Insecta, Lepidoptera), with discussions on their feeding habits and pupation sites

Larval mouthparts are significant organs for the individual development, morphologically related with feeding habits, and providing valuable characters for taxonomy and phylogenetic analysis. In previous studies, larval mouthparts revealed two identifying characters of Notodontidae. However, the evolutionary driving force and exact definition of these structures remain unsatisfactory. In this study, the larval mouthparts of Euhampsonia cristata (Butler, 1877), Fentonia ocypete (Bremer, 1861), Phalera assimilis (Bremer & Grey, 1853), Nerice davidi Oberthür, 1881, Cerura erminea (Esper, 1783) and Furcula furcula (Clerck, 1759) are morphologically observed and compared using scanning electron microscopy (SEM). The larval mouthparts of the six species are commonly equipped with paired maxillary sacs, congruent with the previous descriptions. However, the larval mouthparts of N. davidi are peculiar for bearing toothed mandibles, providing an exception of Notodontidae. Otherwise, the mouthparts exhibit morphological differences on mandibles, spinnerets, labral notches, and setal arrangements among the six species. The morphological diversity and the related feeding and pupation habits are briefly discussed.