CHLOROTHECIUM (Borzi) Pascher 1939, p. 863 



Cells subspherical, clavate, or ellipsoid, attached by a broad flat- 

 tened base or short, thick stipe to a substrate; cells straight or slightly 

 bent if elongate; cell wall smooth, in 2 sections, the upper longer 

 than the lower; chromatophores 1 to many, without pyrenoids ( ? ) ; 

 reproduction by autospores and aplanospores. 



Chlorothecium Pirottae Borzi 1894, p. 139 

 PL 95, Fig. 11 

 Cells club-shaped to elongate-ellipsoid, or clavate, narrowed at 

 the base to form a short, stout stipe with an adhesive disc; chromato- 

 phores 2-4, parietal; contents divided to form (2)-4 or many aplano- 

 spores which are liberated by the gelatinization of the upper part 

 of the cell; cells 6-10/a in diameter, up to 30;u, long. 



Attached to filamentous algae and other submerged aquatic plants. 

 Mich. 



OPHIOCYTIUM Naegeli 1849, p. 87 



An attached or free-floating cylindrical or clavate unicell which 

 may be straight, arcuate, or spirally coiled; sometimes with one end 

 swollen and capitate; solitary or in some species forming corymb- 

 like clusters; poles of the cell truncately rounded, with or without 

 a spine or stipe; chromatophores (3)-4-16 pale yellow parietal discs 

 or plates, without pyrenoids; oil but not starch formed as a storage 

 product; reproduction by autospores or zoospores, liberated by the 

 lifting away of the upper portion of the cell. 



Some species of the genus are attached by the stipe, usually to 

 filamentous algae. It is thought likely that some of the free-floating 

 species are the same as those which are attached and which become 

 planktonic in age, the stipe then appearing as one of the polar spines. 



Key to the Species 

 1. Cells attached, epiphytic ' 



1 . Cells free-floating 5 



2. Plants solitary O. desertum 



2. Plants colonial ^ 



3. Cells with an apical spine O. mucronatum 



3. Cells without an apical spine 4 



4. Cells with a slender stipe, 2-4 times the 



diameter of the cell in length - O gracilipes 



4. Cells with a short, stout stipe, equal to or 



IV. times the diameter of the cell in length .- O. arhuscula 



5. Cells with a spine at each pole " 



5. Cells with a spine at one pole only, or without spines 7 



6. Cells 15-20m in diameter; spine long, up to 40m O. bicuspidatum 



6. Cells smaller, (2.7)-5-10,ti in diameter; spines short and sharp ..O. capitatum 



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