portrait;left lateral

Description:

Lateral view of Metopus hasei (Sondheim, 1929).Synomnyms include Metopus fusus (Vuxanovici, 1962) and Metopus latusculisetus (Tucolesco, 1962). The cell is elongate .The anterior end is twisted to the left resulting in a rounded lip that overhangs the peristome.The spiral peristome is bordered on the left by an adoral zone of membranelles and on the right by five closely spaced kineties,the "perizonal stripe".Just to the right of the posterior termination of the AZM is a short, inconspicuous undulating membrane(usually visible only in silver-stained preparations).The The right somatic kineties parallel the peristome anteriorly and the left somatic kineties terminate at the margin of the peristome.There is a tuft of long caudal cilia. This feature distinguishes M. hasei from flask-like forms of M. palaeformis which lack long caudal cilia. The prominent ellipsoid macronucleus and adjacent micronucleus are in the anterior half. The contractile vacuole is at the posterior end.The cytoplasm contains endosymbiotic methanogenic bacilli.There is an aggregate of brown refractile granules at the anterior end (seen here)typical of the metopid ciliates.Collected from the bottom sediments of an organically enriched rain pool with abundant decaying grass contaminated by Canada goose (Branta canadensis) droppings.Boise, Idaho. January 2006. DIC.