Aulacoseira westfjordensis, a new centric diatom species from Iceland (Aulacoseiraceae, Coscinodiscophyceae)

A new centric diatom, Aulacoseira westfjordensis sp. nov., is described from the Westfjords in northwestern Iceland. The morphology of the species is illustrated using detailed light and scanning electron microscopy observations. Its main discriminating features include the very shallow Ringleiste, the presence of long attenuate spines with an anchor-shaped tip and acute side outgrowths, mantle striae composed of a spiraling, oblique and a straight parallel part, a hyaline discus and marginal valve face areolae.

The new species is compared to related species showing a combination of a hyaline discus and long, thin irregular spines. The species is observed in several weakly acid, soft-water rivers and brooks in the Westfjords.