Ventral surface of the metopid ciliate, Brachonella
spiralis(Smith,1897;Jankowski,1964)stained by a silver carbonate technique(see Foissner, W.Europ. J. Protistol.27,313-330;1991). The body is broadly conical anteriorly with a narrower obliquely truncate posterior. The long S-shaped peristome winds around the entire circumference of the cell terminating in the cytostome. This spiraling cytostome distinguishes Brachonella
from the similar genus Metopus
in which the peristome runs obliquely from anterior to posterior but does not spiral around the long axis. The cytostome is paralleled on the right by a perizonal stripe of kineties and on the left an adoral zone of membranelles (both seen well in this image). Somatic kineties run obliquely anterior to the cytostome and longitudinally posterior to it. A distinctive aggregate of brownish refractile granules typical of most metopids is noted anteriorly. The spherical anterior macronucleus and micronucleus are not seen here. Brachonella
is found in sapropelic habitats and contains methanogenic symbionts in the cytoplasm. From stagnant freshwater source with rotting vegetation near Boise, Idaho. Brightfield.