Sampling date 06/2013. Scale bar indicates 25 µm.

The shape of this species is very similar to Cosmarium meneghinianum and is best distinguished by its size.
C. connatum:            L. 85–100 µm, Br. 60–75 µm, I. 45–60 µm,
C. meneghinianum: L. 63–75 µm, Br. 45–53 µm, I. 38–41 µm.

Furthermore, the sinus of C. connatum is more deeply incised than that of C. meneghinianum.

Place name: Wetland Mittermoos near Fieberbrunn (Tyrol, Austria) 
Latitude: 47.47998695     Longitude: 12.5240922

Microscope Zeiss Universal, camera Canon EOS 600D. DOF image.