60 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 



Division Chrysophyta 

 Class Bacillariophyceae 

 Order Pennales 

 Family Cymbellaceae 

 GENUS AMPHORA Ehrenberg, 1840 (fig. 24) 



MORPHOLOGY 



Cells are commonly sessile, with concave faces attached in girdle 

 view. They are broadly elliptical in outline and have truncated ends. 

 Girdles generally are separated by several punctate or striate inter- 

 calary bands. Values are lunate, longitudinally asymmetrical, and 

 transversely striate. Raphe is gibbous, with a central nodule close to 

 the concave margin. Some species have a single chromatophore which 

 lies next to the concave girdle face; other species have 2 or 4 

 chromatophores. 



REPRODUCTION 



Two gametes are formed from the protoplast of 2 approximate cells 

 and unite to form 2 auxospores. Geitler (1929) observed the production 

 of a single auxospore from a single cell. 



OCCURRENCE 



Amphora is widely distributed. Freshwater species commonly are 

 found in circumneutral waters having a fairly high nutrient content. 



ENVIRONMENTAL CONDITIONS 



Standard 

 Range Mean deviation 



Temperature degrees Celsius__ 0.0 - 



PH 4.9 



Dissolved oxygen milligrams per liter 2.7 - 



Specific conductance micromho__ 22 



Total alkalinity milligrams per liter ■ 



Total hardness do 4 



Total nitrogen do .00- 



Total phosphorus do .0 - 



SPECIES INFORMATION 



Refer to Cleve (1895) and Boyer (1927a). 



