1987 Volume 3 Pages 89-98
The samples examined were collected from the rivulet in Cuzco, Peru. Almost 380 valves were analyzed by light microphotographs. Margins of the valves almost linear to slightly widened toward the center of the valve. Two types are distinguished in the form of the valves. The first type is Navicula type, of which valve is symmetrical with respect to the raphe and the second type is Cymbella type, of which valve is asymmetrical. Most of the valves belong to the Navicula type. Valve with capitate ends is more common than that with rostrate ends. Thirty seven percent of the valve have crooked protruding ends. Striae, at the center of the valve, mostly parallel ( 65% ). The relative frequencies of each characteristics are similar to the specimens from Taitong, Taiwan. Length,9-18μm, breadth 3.5-4.5μm, striae in 10, am,20-25 at dorsal margin,20-24 at ventral margin. The valves in Cuzco are smaller and have denser striae than those in Taitong and previously reported data.
