portrait

Description:

Portrait of the oligotrich ciliate, Romstrombidium hyalinum. This genus is distinguished from the similar Strombidium by the small size and the termination of the spiral somatic ciliary rows before they reach the posterior pole of the cell (in Strombidium they form a terminal spiral). There are several species. R. hyalinum is colorless. The cell body is transversely truncate anteriorly and bluntly conical posteriorly. The cytostome is at the anterior end. A circular adoral zone of membranelles is present. There are six indistinct, slightly spiraling rows of short somatic cilia that extend nearly the length of the body. It is seldom possible to keep more than one row in the focal plane in the lateral view. The C- shaped macronucleus is anterior and transversely oriented The peripheral contractile vacuole is located in the posterior of the cell. A food vacuole is seen here posteriorly. Collected from freshwater pond near Boise, Idaho September 2003. DIC optics.