110 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 



Division Cyanophyta 

 Class Cyanophyceae 

 Order Chyroococcales 

 Family Chroococcaceae 

 GENUS AGMENELLUM Drouet and Daily, 1956 (fig. 49) 



Generic Synonym. -Merismopedia Meyen, 1839 



MORPHOLOGY 



Cells are spherical or almost hemispherical when dividing. They are 

 contained in free-floating, multicelled colonies. Cells, 3-6 ^m wide, are 

 regularly arranged in parallel vertical and transverse rows. The colony 

 is 1 cell in thickness. The gelatinous matrix is homogeneous and col- 

 orless. 



REPRODUCTION 



Reproduction is by cell division and colony fragmentation. 



OCCURRENCE 



Agmenellum is widely distributed and generally is indicative of soft- 

 water and acidic conditions. 



ENVIRONMENTAL CONDITIONS 



Standard 

 Range Mean deviation 



Temperature degrees Celsius__ 0.0 - 36.0 22.5 7.2 



pH 5.6 - 9.4 7.7 .6 



Dissolved oxygen milligrams per liter .1 - 20.6 8.2 2.4 



Specific conductance micromho__ 26 -39,500 1,190 2,720 



Total alkalinity milligrams per liter 1 - 450 120 78 



Total hardness do 4 - 2,000 241 272 



Total nitrogen do .01- 21.0 1.52 1.63 



Total phosphorus do .0 - 3.1 .2 .3 



SPECIES INFORMATION 



Refer to Thompson (1938), Geitler (1930), and Prescott (1962). 



