Johnston's organ and central organ in Nezara viridula (L.) (Heteroptera, Pentatomidae)

The fine structure of Johnston's organ and central organ in Nezara viridula (Heteroptera, Pentatomidae) is described. Johnston's organ consists of 45 scolopidia distributed around the periphery of the distal part of the third antennal segment (distal pedicellite). The scolopidia are anchored separately in invaginations of joint cuticle between the pedicel and flagellum. The scolopidia are amphinematic and each scolopidium comprises three sensory cells and three enveloping cells. The latter are a proximal scolopale cell with a typical labyrinth, an attachment cell filled with many microtubules, and a distal accessory cell also filled with microtubules. Axons of 17 scolopidia gather and join one antennal nerve; 28 scolopidia of the opposite side, extend axons into the other antennal nerve. The central organ consists of seven mononematic scolopidia, which comprise of one or two sensory cells. They anchor in the same joint as the scolopidia of Johnston's organ. The sensory cell bodies of the central organ are located close to the antennal nerves, more proximally than those of Johnston's organ. The axons of four scolopidia join one antennal nerve and those of the remaining three scolopidia join the other antennal nerve. Enveloping cells similar to those in Johnston's organ are present in the central organ.