FINE-STRUCTURE OF THE PREOCELLAR PIT IN TRISSOLCUS-BASALIS (WOLL) (HYMENOPTERA, SCELIONIDAE)

The preocellar pit of both sexes of Trissolcus basalis (Hymenoptera: S celionidae), a solitary egg parasitoid of Nezara viridula, is describe d. Externally, the opening is median, spherical, with an average diame ter 12 mum. Internally, the preocellar pit corresponds to a bell-shape d apodeme (27 mum deep) with smooth cuticular walls, except for the ap ical portion, which is rounded and roughly sculptured. Ultrastructural observations show that the preocellar apodeme apex is connected to th e protocerebrum by a bundle of elongated epidermal cells, which are ve ry rich in microtubules extending from the base to the cell apex. It i s assumed that the apodeme and the epidermal cell bundle act as a susp ension to support the brain. The taxonomic significance of this pit is recognized.