Cytopharyngeal basket annulus

Description :

Detail of the large nassulid ciliate Obertrumia aurea (Ehrenberg, 1833; Foissner 1987). Synonym of Nassula aurea. Obertrumia is distinguished by it's bipartite "hypostomial frange", linear arrays of ciliary tufts. There is a prominent cytopharyngeal basket (nasse) composed of stout nematodesmata at the base of a shallow oral introitus in the anterior 1/3 of the cell. Focal swellings of the nematodesmata give the appearance of a ring (annulus) near the outer end of the nasse. Numerous small mucocysts give the cortex a roughly granular appearance. O. aurea feeds mainly on cyanobacteria. Collected from a freshwater pond near Boise, Idaho November 2003. DIC optics.