Eunotia macroglossa most closely resembles species having kinship with E. minor, E. pectinalis and E. soleirolii. Eunotia macroglossa is set off from all three taxa by the heavily silicified, clearly visible helictoglossae at the valve ends. In valve outline, it is most similar to E. minor, but the ends of E. macroglossa are not as attenuated. Both E. soleirolii and E. pectinalis have parallel edges that end in a slight shoulder at the valve edge, while E. macroglossa has a slightly curved dorsal edge, with the valve ends only very slightly set off from the evenly curved dorsal margin. The helictoglossae of E. macroglossa are positioned further from the apices than in both E. soleirolii and E. pectinalis. Other distinguishing features of E. macroglossa include the radiate striae at the valve apices. These are clearly visible in most LM views at the appropriate level of focus. Eunotia lewisii has a large helictoglossa similar to E. macroglossa, but E. lewisii* has a higher stria density (20-25 in 10 μm). In addition, the dorsal margin of E. lewisii has a row of small spines, which are absent in E. macroglossa. The valves of E. lapponica are more broad with a higher stria density (17-20 in 10 μm) and more strongly dorsally deflected apices than E. macroglossa.

LM scalebar = 10 µm
Eunotia Macroglossa 82 69 E Macroglossa 73 Holotype E Macroglossa Girdler E Macroglossa 60 7R E Macroglossa 51 19R E Macroglossa 41 75R E Macroglossa 25 4
Length Range
21-93 µm
Width Range
4.5-6.6 µm
Striae in 10 µm
11-14 in the valve center, 16-18 near the valve apices.

Also compare to

Eunotia minor

(Kütz.) Rabenh.

Eunotia pectinalis

(Dillwyn) Rabenh.

Eunotia soleirolii

(Kütz.) Rabenh.

Eunotia lewisii

Siver and Hamilton

Eunotia lapponica