portrait

Description:

Portrait (optical coronal section) of Holophrya discolor (Ehrenberg,1833), a common prostome ciliate. Body shape variable from nearly spheroid to oblong. Some species with zoochlorellae. The oral aperture is an anterior apical or somewhat offset invagination. The cytopharynx is supported by fine trichites (seen here). Ciliature is dense and holotrichous with three double rows of kinetids forming a "dorsal brush" extending posterior from the oral aperture about 1/3 the body length. There are some longer caudal cilia. The spherical macronucleus located in the mid-body has a characteristic large nucleolus. The micronucleus is attached to the right posterior of the macronucleus in this image. Small peripheral mucocysts are present. The contractile vacuole is posterior. Numerous food vacuoles are seen. Holophrya sp. are distinguished from the very similar genus, Prorodon, by their spherical or ellipsoid macronuclei. Prorodon sp. typically have sausage shaped or ribbon-shaped macronuclei. Omnivorous. From organically enriched freshwater pond near Boise, Idaho. DIC optics.