Section [Margaritiferae]: Cell surface granulated, gnarled or spiny; semicells pyramidal with flattened apex or trapezoid (Illustrations of The Japanese Fresh-water Algae, 1977).
Species [f. arcticum]: Cell body 35 μm long, 24 μm wide, isthmus 12.6 μm wide, both sides with 6 waves (including basal and apical corners), apex with 2 corners and 2 waves (Illustrations of The Japanese Fresh-water Algae, 1977).
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C. notabile
f. arcticum
42 x 30 μm
single pyrenoid
Hiroshima, 1998
C. notabile
f. arcticum
41 x 31 μm
Numa-no-hara m.
Madarao highland
Niigata, 2006
C. notabile
f. arcticum
40 x 28 μm
Shimo-muneoka
Shiki
Saitama, 2004
C. notabile
f. arcticum
38 x 26 μm
Riverside green l.
Sawara
Chiba, 2004
C. notabile
f. arcticum
38 x 24 μm
single pyrenoid
Hiroshima, 1998
Movies 
C. notabile
f. arcticum
29 x 21 μm
Tanohara Natural p.
Ontake highland
Nagano, 2005
C. notabile ?
or C. formosulum ?
21 x 16 μm
single pyrenoid
Tochigi, 1997
