| Apical cells not hairly; axial filament 8-12 μm in diam. | 
|   S. tenue
 μm
 Inari Park
 Toyama, 2002
 |   S. tenue ?
 10-20 x 5 μm
 Kayoicho-ike
 Fukuoka, 2001
 |   S. tenue ?
 10-22 x 5 μm
 Nishi-Urawa
 Saitama, 2001
 |   S. tenue ?
 stock Ti-3 & Ti-5
 Inari Park
 Toyama, 2002
 | 
|   S. tenue ?
 μm
 Omiya
 Saitama, 2001
 |   S. tenue ?
 μm
 Tone river
 Tsukiyono
 Gunma, 2003
 |   S. tenue
 & st. Taw-12
 11-15 x 6-10 μm
 Watarase river
 Ashikaga
 Tochigi, 2004
 |   S. tenue
 15 x 9 μm
 Furu-tone river
 Kasukabe
 Saitama, 2004
 | 
|   S. tenue
 7-27 x 6-10 μm
 Tama river
 Chofu
 Tokyo, 2004
 |   S. tenue
 10-30 x 6-10 μm
 Karasu river
 Takasakis
 Gunma, 2004
 |   S. tenue
 8-23 x 6-13 μm
 Kurome river
 Asaka
 Saitama, 2004
 |   S. tenue
 μm
 Showa-machi g.p.
 Showa
 Saitama, 2006
 
  | 
|   S. tenue
 μm
 Jinbei-numa
 Motono
 Chiba, 2006
 
  |   S. tenue
 10-25 x 6-7 μm
 drainage ditch
 Kawagoe
 Saitama, 2007
 
  | 
| Apical cells hairly; axial filament 5-8 μm in diam.; no constriction at cell-cell junction | 
|   S. aestivale
 μm
 Itakura Central Park
 Itakura
 Gunma, 2003
 |   S. aestivale ?
 17-24 x 9.5 μm
 Tsukuba
 Ibaraki, 2000
 |   S. aestivale ?
 μm
 Shiroyama Park
 Okegawa
 Saitama, 2006
 
  | 
| Apical cells hairly; axial filament 10-15 μm in diam.; slight constriction at cell-cell junction | 
|   S. subsecundum
 13-25 x 4-9 μm
 Watarase river
 Ashikaga
 Tochigi, 2004
 |   S. subsecundum ?
 μm
 Ootagaya numa
 Tsurugashima
 Saitama, 2003
 |   S. subsecundum ?
 μm
 Mikazuki-bashi
 Ushiku
 Ibaraki, 2002
 |   S. subsecundum ?
 μm
 Onnenai
 Kushiro marsh
 Hokkaido, 2005
 | 
|   S. subsecundum
 20-35 x 4-10 μm
 Ohnuma
 Nasu-shiobara
 Tochigi, 2006
 
  |   S. subsecundum ?
 μm
 Binnuma-gawa
 Fujimi
 Saitama, 2006
 
  | 
| ??? | 
|   S. lubricum ?
 μm
 Tsuki river
 Ranzan
 Saitama, 2003
 |   Stigeoclonium sp. ?
 μm
 Akebono-yama A.P.
 Kashiwa
 Chiba, 2002
 |   Stigeoclonium sp. ?
 μm
 water treatment c.
 Sakado
 Saitama, 2004
 |   Stigeoclonium sp. ?
 μm
 Ikenokochi marsh
 Tsuruga
 Fukui, 2004
 |