The antennal sensilla of the praying mantis Tenodera aridifolia: A new flagellar partition based on the antennal macro-, micro- and ultrastructures

• We identified 6 different types of sensilla on Tenodera aridifolia's antennae.
• We devised a new division to separate the different parts of the flagellum.
• Males possess a huge number of grooved peg sensilla in T. aridifolia.
• Pheromone receiving sensilla are double-walled in mantis.
• The antennal development might comprise two distinct sites of flagellar division.

In insects, the antenna consists of a scapus, a pedicellus, and a flagellum comprising many segments (flagellomeres). These segments possess many morphological types of sensory organs (sensilla) to process multimodal sensory information. We observed the sensilla on flagellomeres in praying mantis (Tenodera aridifolia) with both scanning and transmission electron microscopes. We classified the sensilla into six types: chaetic, campaniform, coelocapitular, basiconic, trichoid and grooved peg sensilla, and inferred their presumptive functions on the basis of their external and internal structures. In addition, based on their distribution, we newly divided the flagellum into 6 distinct parts. This new division leads to a better understanding about the sexual dimorphism and the antennal development in the mantises. The sexual difference in distribution of the grooved peg sensilla suggests that this type of sensilla may play a role in sex-pheromone detection in mantis, which is a rare case of double-walled sensilla mediating this function.

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