Remarks: Specimen with a more open sinus and straight, almost parallel sides are considered to belong to Cosmarium pseudamoenum Wille. In the material that I have studied this distinction was difficult to make.
Notice that the two rows of granules just under and above the sinus of specimen 2008004007 are well separated, while those of specimen 2011030027 are so close associated that the base of the granules are merged with each other.