Compare Semiorbis eliasiae
Both Semiorbis rotundus and S. hemicyclus have larger, even more strongly arched valves.
Semiorbis catillifera has sub-rostrate apicies, and less valve curvature.
Semiorbis hemicyclus
has valves that are slightly less curved and less protracted.
LM scalebar = 10 µm
Length Range
16.5-40.5 µm
16.5-40.5 µm
Width Range
3.5-5.7 µm
3.5-5.7 µm
Striae in 10 µm
8-12
8-12
Length Range
32.9-45.1 µm
32.9-45.1 µm
Width Range
3.9-4.8 µm
3.9-4.8 µm
Striae in 10 µm
12-13
12-13
Length Range
17-40 µm
17-40 µm
Width Range
4.8-5.3 µm
4.8-5.3 µm
Striae in 10 µm
12-13
12-13
Length Range
11.7-28.1 µm
11.7-28.1 µm
Width Range
2.5-4.5 µm
2.5-4.5 µm
Striae in 10 µm
11-14
11-14
