COMPARATIVE ULTRASTRUCTURE OF THE CYTOPLASM IN SPECIES OF THE GENUS TRACHELORAPHIS (CILIOPHORA, KARYORELICTIDA) .1. SOMATIC CORTEX

The somatic kineties, the myonemes, the dorsal non-ciliated stripe, th e cortical granules and the rhabdocysts are described in four species of the genus Tracheloraphis: Tr. phoenicopterus, Tr. totevi, Tr. crass us, and Tr. caudatus. The somatic kineties carry kinetosome pairs of w hich both are usually ciliated. Less frequently, only the anterior kin etosome is ciliated. Each kinety is accompanied on its right by a stro ng lamellated postciliodesma and, on its left, by a prominent longitud inal microfilamentous myoneme. Tr. totevi has also thinner transverse myonemes which are more superficial than the longitudinal ones. The ki netosome pairs show a set of typical fibrillar derivatives: the poster ior kinetosome has a strong postciliary fibre joining the postciliodes ma and a short hooked kinetodesmal filament, the anterior kinetosome s hows a transverse fibre of seven microtubules. Each ciliary row is und erlain by a subkinetal fibre directed backwards and consisting of up t o 10 sheets of microtubules. The basal end of a kinetosome is closed b y a dense basal plate; the intermediate zone is short and consists of a cup-formed septum and a large axial granule. The cortex displays ref ractile subpellicular bodies which are pigmented in some species and c ontain dense granular material, and rhabdocysts consisting of a concen trically-structured ''head'', a shaft and a basal vesicle. Incomplete extrusion of rhabdocysts has been observed. The basal vesicle swells a nd the shaft moderately elongates upon extrusion.