102 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 



Division Pyrrophyta 

 Class Dinophyceae 

 Order Peridiniales 

 Family Glenodiniaceae 

 GENUS GLENODINIUM Stein, 1883 (fig. 45) 



MORPHOLOGY 



Solitary, motile cells are asymmetrically globose but may be slightly 

 dorsoventrally flattened. 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 

 2-9 apical, 0-4 anterior intercalary, and 6-12 precingular plates; 

 hypotheca has 5-12 postcingular, 0-2 posterior intercalary, and 1-2 an- 

 tapical 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 



Reproduction is isogamous by the union of gymnodinoid gametes. 

 Each zygote forms 4 zoospores. 



OCCURRENCE 



The genus is generally found in the tychoplankton; however, it can 

 occur in the euplankton. It seems to prefer soft- water conditions. 



ENVIRONMENTAL .CONDITIONS 



Standard 

 Range Mean deviation 



Temperature degrees Celsius__ 0.0 - 34.0 



pH 4.6 - 9.2 



Dissolved oxygen milligrams per liter .1 - 22.0 



Specific conductance micromho 11 -42,100 



Total alkalinity milligrams per liter - 477 



Total hardness do 6 - 1,700 



Total nitrogen do .00- 11.0 



Total phosphorus do .0 - 3.2 



SPECIES INFORMATION 



Refer to Schiller (1933) and Prescott (1962). 



