[Structure of eyes in trombidioid mites (Acariformes: Trombidioidea)]

The eyes or ocelli of trombidioid mite larvae of Euschoengastia rotundata, Hirszutiella zachvatkini and Camerotrombidium pexatum, and larvae and adults of Platytrombidium fasciatum were studied by means of transmission electron microscopy. These species together with larvae of Odontacarus efferus, Ericotrombidium hasgelum, Walchia chinensis and adult E. rotundata and H. zachvatkini were also studied under scanning electron microscope. The eyes of larvae are not inverted and characterized by an epicuticular lamellar lens. The group of phoreceptor cells with rhabdomeres arranged typically of Chelicerata is underlaid by a pigment cup. The eyes of adult mites are inverted, perikarions of photoreceptor cells are situated between the lens and rhabdomeres; tapetum occupies the space between the pigment cup and rhabdomeres. Sensitivity of eyes to light is similar to that of primary eyes of spiders dwelling on soil surface.