The Compound Eye of the Soybean Beetle, Anomala rufocuprea MOTSCHULSKY (Coleoptera : Scarabaeidae)

The structure of the compound eye of the soybean beetle, Anomala rufocuprea, which is nocto-diurnally active, was observed with light and electron microscope. The eye is the typical superposition eye with eucone ommatidia. In the cone sheath, the libosome particles on the concentric endoplasmic reticulum appeared in dark adapted state whereas they were obscured during the light adaptation. The proximal tip of the cone cells extended about 20μm long as the cone tract during light adaptation. They invaded the intercellular spaces of the retinula cells and reached their nuclear level. The principal pigment cells extended proximally in the light adapted state, and the pigment grains were about 0.4μm in diameter in the distal region, while at the proximal part they were 1.5μm. The pigment grains in the accessory pigment cells were restricted to the area above the nuclear level of retinula cells. These pigment grains were about 0.9μm in diameter in the distal region and about 1.2μm at the proximal level. Seven of eight retinula cells contributed to the rhabdom formation. One of the rhabdomeres was situated at the most distal point and was formed by long and anomalous microvilli. The rhabdom layer was surrounded by more than 40 tracheoles which formed the tapetum.