Portrait (lateral view) of the cryptomonad flagellate, Rhodomonas
(Karsten,1898). The cells are laterally flattened. The anterior end is obliquely truncate and the posterior rounded. Two subequal flagella insert into a ventral furrow-gullet complex. A single contractile vacuole is seen adjacent to the anterior opening of the ventral furrow. The inner layer of the periplast is composed of overlapping rounded or square proteinaceous organic plates about 0.4 um in diameter. There is a single large boat-shaped chloroplast with a small pyrenoid. Although not always this color, this species is red due to a chloroplast containing Cr-phycoerythrin 545. Like other cryptomonads, ultrastructural studies of Rhodomonas
reveal a nucleomorph associated with the plastid. The nucleomorph is thought to represent a nuclear remnant of an ancestral endosymbiotic red alga. The function, if any, of the nucleomorph is unknown. Large ejectosomes are seen here lining the ventral furrow-gullet. Rhodomonas
is phototrophic. This genus is found in both freshwater and marine habitats. This specimen was collected from a commercial saltwater aquarium in Boise, Idaho, September 2004. DIC.