1 04 ALGAE IN PH YTOPL ANKTON OF THE UNITED STATE S 



Division Pyrrophyta 

 Class Dinophyceae 

 Order Peridiniales 

 Family Peridiniaceae 

 GENUS PERIDINIUM Ehrenberg, 1830; emend., Stein, 1883 



(fig. 46) 



MORPHOLOGY 



Solitary, motile cells are spherical, ovoid, or angular and may or may 

 not have short apical and antapical horns. The cell is surrounded by a 

 definite number of plates arranged in a specific manner. Cell wall is 

 divided near the center into an apical epitheca and an antapical 

 hypotheca. Epitheca has 4 apical, 2-3 anterior intercalary, and 7 prec- 

 ingular plates; hypotheca has 5 postcingular and 2 antapical plates. A 

 longitudinal sulcus extends from the girdle into the hypotheca. There 

 are 2 flagella. A prominent eyespot may be present. Numerous 

 chromatophores are brown. 



REPRODUCTION 



Aplanospores are formed by division of the protoplast. 



OCCURRENCE 



The alga is of widespread distribution in the euplankton and 

 tychoplankton. 



ENVIRONMENTAL CONDITIONS 



Standard 

 Range Mean deviation 



Temperature degrees Celsius 0.0 - 33.0 



pH 4.6 - 9.6 



Dissolved oxygen milligrams per liter .8 - 18.7 



Specific conductance micromho 26 -30,000 



Total alkalinity milligrams per liter 3 - 477 



Total hardness do 5 - 2,000 



Total nitrogen do .05- 13.0 



Total phosphorus do .0 - 2.2 



SPECIES INFORMATION 



Refer to Lefevre (1932) and Prescott (1962). 



