FINE-STRUCTURE AND SYSTEMATIC POSITION OF ENCHELYOMORPHA-VERMICULARIS(SMITH, 1899) KAHL, 1930, AN ANAEROBIC CILIATE (PROTOZOA, CILIOPHORA)FROM DOMESTIC SEWAGE

Enchelyomorpha vermicularis is a pouch-like ciliate having not only a holotrichous ciliature but also many short, tentacle-like processes on the cell surface. Its systematic position thus varied, depending on t he characters used, between the suctorians and the haptorid gymnostome s, and a recent investigation using refined light microscopic methods could also not clarify the situation. We thus examined some stages of the life cycle of E. vermicularis and studied its fine structure with the transmission electron microscope. The results definitely show that E. vermicularis is the swarmer of a small, globular suctorian with te ntacles irregularly distributed on the anterior body half. The tentacl es, which are not associated with barren basal bodies, contain the bar rel-shaped haptocysts and the two concentric microtubule cores typical of ''good'' suctorians. Furthermore, the cortex possesses small pits and the fine structure of the somatic kinetids is also very similar to that known from other suctorian swarmers, although the kinetodesmal f ibre is anchored to the epiplasm and subkinetal microtubules are proba bly absent. The kinetids are rotated 90 degrees counter-clockwise with respect to the longitudinal body axis causing the ciliary rows to ext end transversely. Usually, two swarmers are produced simultaneously by endogenous budding. Enchelyomorpha vermicularis lacks a scopuloid and mitochondria but possesses cytoplasmic inclusions resembling hydrogen osomes, indicating that it is a true anaerobic ciliate, which is in ac cordance with most faunistic data. The mode of swarmer production, the organization of the swarmer, and the fine structure of the tentacles show that Enchelyomorpha is an entotropid suctorian, belonging to the suborders Acinetina or Discophryina. Acinetid affinities are indicated by the fine structure of the tentacles and the general organization o f the swarmer, whereas swarmer production resembles Cyathodinium in th e suborder Discophryina. Obviously, Enchelyomorpha has a highly distin ct combination of characters which suggests at least separation at fam ily level, i.e. maintenance of the family Enchelyomorphidae Augustin a nd Foissner, 1992.