MORPHOLOGY AND ECOLOGY OF SIROLOXOPHYLLUM-UTRICULARIAE (PENARD, 1922)N-G, N-COMB (CILIOPHORA, PLEUROSTOMATIDA) AND AN IMPROVED CLASSIFICATION OF PLEUROSTOMATID CILIATES

The morphology and infraciliature of Siroloxophyllum utriculariae (Pen ard, 1922) n. g., n. comb. were studied in live cells, with the scanni ng and transmission electron microscope, as well as in specimens impre gnated with protargol and silver carbonate. The new genus, Siroloxophy llum, belongs to the Loxophyllidae and has a specific combination of c haracters, viz. an oral bulge surrounding almost the entire cell, thre e perioral kineties, a single brush kinety, and a single right dorsola teral kinety. The ecology and faunistics of S. utriculariae are review ed. It is a rare and infrequent predator preferring clean freshwaters. The somatic monokinetid of S. utriculariae has typical haptorid ultra structure, including two transverse microtubular ribbons. The oral bul ge is patterned string-like with riffles containing the transverse mic rotubular ribbons originating from the oral kinetids. Perioral kinetie s 1 and 2 consist of dikinetids having one basal body each ciliated; t he nonciliated basal body is associated with a nematodesmal and a tran sverse microtubular ribbon. Perioral kinety 3 consists of ciliated mon okinetids having a fine structure similar to the somatic kinetids; the y form triads with the dikinetids from perioral kinety 2. The classifi cation of pleurostomatid ciliates is reviewed. Two suborders (Amphilep tina, Litonotina) and three families (Amphileptidae, Litonotidae, Loxo phyllidae n. fam.) are recognized and defined.