C. constricta, 68 and 55 µm
Corythion constricta (Certes, 1889) Jung, 1942
Diagnosis: As for C. dubium, but much larger (>45 µm) and with well developed pseudostomal border.
Dimensions: Jung (1942): Shell length 68—74 µm; width 50—56 µm. Vucetich (1975): Length 79—83 µm. My measurements: Length 49—72 µm (see table below).
Ecology: Sphagnum and mosses.
Morphometry of Corythion dubium in one sample from a Sphagnum bog in Amersfoort, the Netherlands. Three groups can be distinguished. The left shell represents the middle group and is 35 µm long, the other shell, possibly C. constricta, is 56 µm and represents the population to the right.
Corythion cf constricta, each shell 72 µm
Corythion cf constricta 72 µm
C. constricta a-b: after Jung (1942); d: after Vucetich (1975)