Portrait

Description :

Portrait (ventral aspect) of the large hypotrich ciliate, Euplotes eurystomus (Wrześniowski, 1870). The pellicle is colorless and inflexible. The lateral sides are approximately parallel. Anteriorly a rounded pellicular collar protrudes beneath the prominent adoral zone of membranelles (AZM). The somewhat sigmoid AZM of E. eurystomus differs from that of the very similar E. aediculatus which is relatively straight. A short undulating membrane is visible at the posterior end of the right peristomal margin. There are nine frontoventral cirri, 5 transverse cirri, 2 left marginal cirri and 2 caudal cirri often appearing frayed at their tips. There are 9 - 11, (usually 10) rows of dorsal bristles in longitudinal furrows. These dorsal bristle complexes have a complicated structure consisting of dikinetids at the base of a shallow pellicular pit with only the anterior one bearing a bristle. A rosette of cortical ampullae resembling mucocysts radiates from each complex. These dorsal bristles are probably not locomotary but may have a sensory function. The macronucleus is 3 shaped. A small spherical micronucleus sits in a shallow notch at the anterior left edge of the macronucleus. The contractile vacuole is located posteriorly on the right. E. eurystomus feeds on bacteria, flagellates, algae and ciliates. Collected from a freshwater aquaculture pond near Boise, Idaho. DIC.