Phylum: Ochrophyta  Family: Fragilariaceae

Asterionella formosa Hassall, 1850

Widespread in benthic conditions. They have no means of locomotion and rely on currents

References: 
Kelly (2000) Identification of Common Benthic Diatoms in Rivers
Canter-Lund (1998) Freshwater Algae: their microscopic world explored