Navicula transitans var. derasa

Navicula transitans var. derasa (Grunow) Cleve 1883 is quite common in the Arctic Ocean, and it's the counterpart to Navicula kariana var. detersa. They both have striae partly hidden around the raphe. Counting, I call them Navicula blotted and Navicula blotted wide. This one is blotted, kariana is wide.

This species remained unnamed in my counts for a long time because of the size of the Bering Sea specimens. While it's supposed to be up to 72 um long, mine are up to 110 um, which is even longer than the nominative variety (105 um). Every other feature in the description matches, but there is a possibility it's not N. transitans. Should you happen to have any suggestions on the identity, let me know!

The most useful paper: Poulin, M. and A. Cardinal (1982) Sea ice diatoms from Manitounuk Sound, southeastern Hudson Bay ( Quebec, Canada). II. Family Naviculaceae, genus Navicula. Canadian Journal of Botany 60: 2825-2845.