Olsson, A. A., 1932. Contributions to the Tertiary Paleontology of Northern Peru: Part 5, The Peruvian Miocene. Bulletins of American Paleontology, 19 (68        ).
        
            New Species-Group Names:
            
                - 
                    sophus Olsson, 1932. p. 154. pl. 16. f. 6. 8-9. 
                
                 
                - 
                    spiekeri Olsson, 1932. p. 153. pl. 16. f. 5. 7.