80 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 



Division Chrysophyta 

 Class Bacillariophyceae 

 Order Pennales 

 Family Gomphonemataceae 

 GENUS GOMPHONEMA Agardh, 1824 (fig. 34) 



MORPHOLOGY 



Cells are commonlyy epiphytic on the ends of dichotomously branch- 

 ed gelatinous stalks. They are sometimes sessile or solitary and free 

 floating. Cells are transversely asymmetrical in both valve and girdle 

 views. Cells are straight, lanceolate, or clavate. One pole is capitate or 

 broader than the other. Intercalary bands are lacking. The raphe is 

 straight and central and polar nodules are conspicuous. Striations are 

 strictly transverse or somewhat radial. The chromatophore is a single, 

 lobed plate. 



REPRODUCTION 



The protoplasts of 2 cells each form 2 gametes, which unite to form 2 

 auxospores. 



OCCURRENCE 



The alga is widely distributed. Freshwater species are generally 

 epiphytic, but they occur commonly in the euplankton and 

 tychoplankton. 



ENVIRONMENTAL CONDITIONS 



Standard 

 Range Mean deviation 



Temperature degrees Celsius 0.0 



pH 4.3 



Dissolved oxygen milligrams per liter .8 



Specific conductance micromho 12 



Total alkalinity milligrams per liter 



Total hardness do 4 



Total nitrogen do .00- 



Total phosphorus do .0 



SPECIES INFORMATION 



Refer to Boyer (1927a). 



