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Eunotia rhomboidea is similar to E. papilioforma because the widths of valve apices are not symmetric (one end is wider than the other). Valves of E. rhomboidea are, on average, narrower than valves of E. papilioforma. In E. papilioforma the positions of the helictoglossae relative to the valve apices can vary between valve apices within a specimen and among specimens within a population, where in E. rhomboidea, the positions of the helictoglossae are more consistent among specimens and within populations. Valves of E. rhomboidea are asymmetric in regard to apex width. Also, the helictoglossa are not as inset (or far) from the apices, in contrast to valves of E canicula and E. incisa which are symmetrical to transapic axis and have helictoglossae farther from (more inset) from the apices. The terminal raphe end curves on to the valve face in E. rhomboidea in contrast to E. incisa where the small groove of the distal raphe end lies in the mantle.

LM scalebar = 10 µm
Eunotia rhomboidea LM6 Eunotia rhomboideaLM3 Eunotia rhomboideaLM2 Eunotia rhomboideaLM4 Eunotia rhomboidea LM7 Eunotia rhomboideaLM5 Eunotia rhomboideaLM1
Length Range
18.0-25.6 µm
Width Range
2.7-3.8 µm
Striae in 10 µm
15-17 in the center valve

Eunotia papilioforma

Furey, Johansen and Lowe 2011

Eunotia apilioforma LM5 Eunotia apilioforma LM3 Eunotia apilioforma LM2 Eunotia apilioforma LM1 Eunotia apilioforma LM6 Eunotia apilioforma LM4
Length Range
13-35 µm
Width Range
3.3-4.8 µm
Striae in 10 µm
13-16

Eunotia incisa

W.Sm. ex W.Greg. 1854

Eunotia incisa LM6 Eunotia incisa LM5 Eunotia incisa LM4 Eunotia incisa LM3 Eunotia incisa LM2 Eunotia incisa LM1 Eunotia incisa LM7
Length Range
12-50 µm
Width Range
2.8-5.0 µm
Striae in 10 µm
16-21 in the center valve

Eunotia canicula

Furey, Lowe and Johansen 2011

Eunotia canicula LM5 Eunotia canicula LM3 Eunotia canicula LM Eunotia canicula LM2 Eunotia canicula LM1 Eunotia canicula LM5 Eunotia canicula LM4
Length Range
20-35 µm
Width Range
3.5-4.0 µm
Striae in 10 µm
14-15, areolae >35