Antennal sensory structures in Nepticulidae (Lepidoptera) and their phylogenetic implications

Antennae of representatives of most genera and subgenera of Nepticulidae have been examined in detail with SEM. Flagellar segments are highly uniform and possess each 1–3 s. trichodea, 1–3 long s. chaetica type I, 12 short s. chaetica type II and 0–2 s. coeloconica of a simpified type without “picket fence”. The dominating structure is a pair of s. vesiculoclada, a unique sensillum type, believed to be a synapomorphy for the Nepticulidae. A pair is present on alt flagellomeres in male antennae but not on all flagellomeres of females in two subgenera of Ectoedemia. Principally each s. vesiculocladum is five-branched, with the branches joined tightly to the flagellar cuticle, but reduction of the branches occurs in several genera, in particular in Ectoedemia. This sensillum can be classified as a single-walled wp sensillum, and thus a chemoreceptor. The s. vesiculocladum is considered to be a homologue of the ascoid sensilla in the Opostegidae. The presence of these special setae is considered as an additional synapomorphy for both families. A review of previous Literature on lepidopteran sensilla is presented and the present data are compared and discussed. In the Nepticulidae the s. vesiculocladum is assumed to be the major pheromone detector in contrast to the s. trichodea of most other Lepidoptera.