| 
Inner side slightly concaved; L/W=7-14 | 
| 
Cell body more than 40 μm in width | 
 
	 var. acerosum
	 40 samples
	 197-692 μm
	 L/W=7.5-14.2
	 1998-2007 | 
 
	 var. acerosum
	 40 samples
	 197-692 μm
	 L/W=7.5-14.2
	 1998-2007 | 
 
	 var. acerosum
	 40 samples
	 197-692 μm
	 L/W=7.5-14.2
	 1998-2007 | 
 
	 var. acerosum
	 40 samples
	 197-692 μm
	 L/W=7.5-14.2
	 1998-2007 | 
| 
Cell body 20-40 μm in width | 
 
	 var. acerosum
	 13 samples
	 206-560 μm
	 L/W=12-16
	 1999-2006 | 
 
	 var. acerosum
	 13 samples
	 206-560 μm
	 L/W=12-16
	 1999-2006 | 
 
	 var. acerosum
	 13 samples
	 206-560 μm
	 L/W=12-16
	 1999-2006 | 
 
	 var. acerosum
	 13 samples
	 206-560 μm
	 L/W=12-16
	 1999-2006 | 
| 
Cell body small (194-410 μm); L/W=7-11 | 
 
	 var. minus ?
	 14 samples
	 194-484 μm
	 L/W=6-10
	 1998-2007 | 
 
	 var. minus ?
	 14 samples
	 194-484 μm
	 L/W=6-10
	 1998-2007 | 
 
	 var. minus ?
	 14 samples
	 194-484 μm
	 L/W=6-10
	 1998-2007 | 
 
	 var. minus ?
	 14 samples
	 194-484 μm
	 L/W=6-10
	 1998-2007 | 
| 
Cell body long (388-915 μm), central region nearly straight; L/W=15-33 | 
 
	 var. elongatum
	 21 samples
	 303-892 μm
	 L/W=17-23
	 1998-2008 | 
 
	 var. elongatum
	 21 samples
	 303-892 μm
	 L/W=17-23
	 1998-2008 | 
 
	 var. elongatum
	 21 samples
	 303-892 μm
	 L/W=17-23
	 1998-2008 | 
 
	 var. elongatum
	 21 samples
	 303-892 μm
	 L/W=17-23
	 1998-2008 | 
| 
Inner side slightly convexed (336-494 μm); L/W=8-12 | 
 
	 var. tumidum ?
	 312 x 19 μm
	 L/W=16
	 laminae irregular
	 Saitama, 1999 |