A new type of arthropod photoreceptor

A new type of photoreceptor for the phylum Arthropoda, found in the class C ollembola (Arthropoda, Hexapoda) is reported. This new light-sensitive stru cture consists of a pair of interocular vesicles present in the genus Vesic ephalus Richards, 1964 and is anatomically related to the cluster of ommati dia. The absence of a lens, the presence of a rabdome in the upper part of the vesicle and the reflection and refraction of light by a hemolymph bubbl e with incidence to the rhabdomeric structure are the main traits of this n ew photoreceptor. (C) 2001 Elsevier Science Ltd. All rights reserved.