COMPARATIVE ULTRASTRUCTURE OF THE CYTOPLASM IN SPECIES OF THE GENUS TRACHELORAPHIS (CILIOPHORA, KARYORELICTIDA) .3. BUCCAL APPARATUS

The structure of the apical mouth has been studied in Tracheloraphis d ogieli, Tr. phoenicopterus, Tr. totevi and Tr. caudatus. There is no p ermanent cytostome in any of them. The apical surface is covered by on ly the plasma membrane with many extrusomes of the type of subpellicul ar bodies (pigmentocysts) beneath it. In Tr. dogieli, the apical area is flat and surrounded with a circular ''lip''. In Tr. phoenicopterus, the apical surface is dome-shaped, and the cytoplasm of the body ''he ad'' is filled with refringent oval electron-lucent granules up to 2 m u m in size, clearly different from the extrusomes. The peribuccal cil iature of Tracheloraphis includes a specialized circumoral kinety inde pendent of the meridional somatic kineties. In most species, this kine ty consists of paired kinetosomes, one ciliated and one barren. Howeve r, in Tr. dogieli the circumoral ciliature consists of a series of sho rt radial rows of kinetosomes, at least four kinetosomes in each row ( 2 ciliated and 2 barren). The innermost kinetosome, which is barren, s ends a ribbon of transverse microtubules towards the apical area. This kinetosomal array is immediately outside the circular ''lip''. The ci lia of these kinetosomes are directed forward and form the apical cili ary ''crown''. Nemadesmata start from the kinetosomes of the ''crown'' , both ciliated and barren, and are directed obliquely backwards. The somatic kineties, formed by dikinetids, begin well behind this ''crown '' and are not connected with it. They bear no nemadesmata.