16 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 



Division Chlorophyta 

 Class Chlorophyceae 

 Order Chlorococcales 

 Family Oocystaceae 

 GENUS ANKISTRODESMUS Corda, 1838; emend., Ralfs, 

 1848 (fig. 2) 



MORPHOLOGY 



Cells are acicular to fusiform, straight, curved, or sigmoid. Diameter 

 ranges from about 1 to 4 /*m; cells length varies from 15 to 80 fim. Cells 

 are generally singular but may be loosely aggregated. The single 

 chromatophore is parietal. 



REPRODUCTION 



The cell divides longitudinally into 2, 4, or 8 autospores. 



OCCURRENCE 



Ankistrodesmus is widely distributed in the euplankton, but it rarely 

 occurs in abundance. According to Smith (1950), aquariums and other 

 receptacles containing water that has been standing in the laboratory 

 for some time may contain a virtually unialgal culture of the alga. The 

 commonly occurring species, Ankistrodesmus falcatus, is generally 

 found in acidic water of high temperature, where there is a dense con- 

 glomeration of other algae. 



ENVIRONMENTAL CONDITIONS 



Standard 

 Range Mean deviation 



Temperature degrees Celsius 0.0 - 36.0 



pH 3.4 - 10.0 



Dissolved oxygen milligrams per liter .1 - 22.0 



Specific conductance micromho 10 -50,000 



Total alkalinity milligrams per liter n 500 



Total hardness do 3 - 2,000 



Total nitrogen do .00- 41.0 



Total phosphorus do .0 - 3.9 



SPECIES INFORMATION 



Refer to Brunnthaler (1915) and Prescott (1962). 



