Pinnularia Borealis Lanceolata Guide
Credit: Loren Bahls
  1. Valves elliptic-lanceolate
  2. Apices acutely rounded
  3. Proximal raphe slightly deflected

Pinnularia borealis var. lanceolata has small elliptic-lanceolate valves with a maximum width of about 12 µm. Apices are rounded. The proximal raphe ends are only slightly laterally deflected. The broad striae number 5-6 in 10 µm.