ИСТИНА

Oweniidae is among families which seem to be the nearest to the basal root of annelid tree – to the last common annelid ancestor. Detailed morphological investigation are necessary to support this phylogenetical statements. To evolve the annelid eyes ultrastrucutre comparison we decided to start first of all with Oweniidae eyes study. Amphinomidae derived later on than Oweniidae, and Amphinomidae possesses well developed 2 pairs of normal converse adult cerebral eyes. The data about Oweniidae eyes structure can help to reconstruct ground pattern of annelid adult eyes. The eyes of Galatowenia oculata and Owenia fusiformis were studied with light microscopy and TEM. Both species bear one pair of pigmented eyes on the lateral sides of prostomium, some specimens of G. oculata have additional pigmented strips running to the dorsal side. In both species pigmented cells form a spot, some area within epidermis, not a cup, they are distributed loosely. In G. oculata presumable photoreceptor cells bear one cilia and most of their cytoplasm is filled with large elongated mitochondria and a lot of vacuoles with electron-lucent content and invaginations, similar cells occur within the pigmented strips also. The apical parts of pigmented and unpigmented supportive cells posses large vacuoles with homogenous contents of moderate electron density protruding towards cuticle and forming lens-like structure. The data assume that the eyes of oweniids are not typical adult annelids eyes. The work was financially supported by DAAD “Ostpartnerschaftsprogramm“ and Lomonosov Moscow State University and DAAD “Vladimir Vernadskij” Programm in 2016