Fine structure of the compound eyes of callitettix versicolor (Insecta: Hemiptera)

Abstract

The external morphology and internal anatomy of the compound eyes of the adults of the rice spittlebug Callitettix versicolor (F., 1794) (Insecta: Hemiptera: Cercopidae) are described for the first time with light, scanning, and transmission electron microscopy observations. The eyes of C. versicolor are of the apposition type and each eye consists of ∼2,042 ommatidia. Each ommatidium is composed of a plano-convex corneal lens, a eucone-type crystalline cone, eight retinular cells, two primary pigment cells, and an undetermined number of secondary pigment cells (probably six). The rhabdomeres of the eight retinular cells form a centrally fused rhabdom surrounded by palisades. The distal end of the rhabdom is funnel shaped around the proximal region of the crystalline cone. The microvilli of the rhabdom are arranged in orthogonal directions suggesting polarization sensitivity. With a small F-number of 1.48 and a large interommatidial angle Δφ of 7.7°, the eye possesses high light sensitivity but low spatial resolution. With a large ommatidial acceptance angle Δρ of 11.6°, the eye can merely form a burred image of its surroundings, but the ratio Δρ/Δρ of 1.5 indicates that the eye can provide a relatively good contrast.