Cells larger and wider than the standard type, measuring between 16 to 54 micrometers in diameter. The calyptrae, due to this increased diameter, exhibit a more pronounced and abrupt tapering, making the process more prominent. The structure is extremely delicate, although in many cases, it appears coarser than in the standard type. The cell wall is finely punctuated, with the puncta arranged in quincunx rows, which are short and therefore seem to appear irregular.