COMPOSITE, HAUSTELLATE MOUTHPARTS IN NETWINGED BEETLE AND FIREFLY LARVAE (COLEOPTERA, CANTHAROIDEA, LYCIDAE, LAMPYRIDAE)

During lycid embryogenesis, labral and mandibular anlagen develop sepa rately. Each anterolateral corner of the labrum elongates into a style t, while the whole of each mandible involutes into a flute that is ope n to the lateral aspect. The stylets and flutes interlock in such a wa y as to leave canals, fashioning left and right haustellate apparatuse s. During lampyrid embryogenesis, only one pair of anlagen forms inste ad of two. The pair matures into sharp, arcuate appendages that appear to be typical mandibles, but nevertheless a canal forms internally. T he canal is not formed by coadaptation of two appendages; instead, cel ls within the pair create the canal autonomously. Indications are that the canal is homologous between these two families. It is suggested t hat in lampyrids, labral and mandibular cell fields develop together i n the same anlage but behave according to their own respective program s, forming the canal with morphogenetic movements that are comparable to those of lycids. (C) 1994 Wiley-Liss, Inc.