Neither apposition nor superposition: the compound eyes of the Chestnut Leafminer Cameraria ohridella

The two lemon-shaped compound eyes of the moth Cameraria ohridella measure in dorsal–ventral direction 263.0 μm in male and 238.9 μm in female individuals. In anterior–posterior direction no significant differences were found between the sexes, eye length being about 194.6 μm. The eyes of males consist of ca. 417 hexagonal facets, while those of females contain 367. In both sexes facet diameters are approximately 11.5 μm. Despite the size differences of the eyes in the two sexes, ultrastructurally they are identical and both possess ommatidia of 80 μm mean length. The ultrastructure of the eye is described and compared with that of other compound eyes of Lepidoptera. Anatomically the eyes represent a type intermediate between apposition and refractive superposition kind. A distal rhabdom is present in the space that in the eyes of larger moths with superposition optics is occupied by the so-called clear zone. A tracheal tapetum and longitudinal screening pigment migrations, typical of superposition but not apposition eyes are present despite the lack of a clear zone. Thus, our results support an earlier calculated minimal theoretical limit for superposition eyes.