Morphology and morphogenesis of Pseudoamphisiella lacazei (MAUPAS, 1883) SONG, 1996 with suggestion of establishment of a new family Pseudoamphisiellidae nov fam (Ciliophora, Hypotrichida)

The morphology and morphogenesis of the hypotrichous ciliate Pseudoamphisiella lacazei (MAUPAS, 1883) SONG, 1996 (formerly Holosticha lacazei MAUPAS, 1883) isolated from coastal waters of Qingdao (Tsingtao), People's Republic of China are described using protargol silver impregnation. Improved diagnoses of the genus Pseudoamphisiella and of P. lacazei are presented. Some characters (the origin of the right marginal cirri and the absence of frontoterminal cirri) are sufficiently different from other hypotrichs to suggest the erection of a new family, Pseudoamphisiellidae, nov. fam. The morphogenetic investigation on P. lacazei shows that the numerous oblique frontoventral transverse (FVT) streaks generate only three rows of cirri: two ventral rows and a row of highly developed transverse cirri. Thus it has midventral rows which, nevertheless, occur in an unusual interphase pattern as two distinctly separate ventral ones. The right marginal row in both proter and opisthe originate, uniquely, from the last FVT-anlage. Generally, all anlagen develop de novo except those of the left marginal row and dorsal kineties, which derive from disaggregated parental cirri or kineties. The parental adoral membranelles and undulating membranes are completely renewed during the cell division. The caudal cirri, which develop from the posterior end of each dorsal kinety anlage, connect with the left and right marginal rows and are therefore very difficult to recognize in the interphase. The phylogenetic position of the new family is discussed but for the time being remains Hypotrichida incertae sedis.