Character	Lutophila	Biremis 1,2	Oestrupia 1,3	Krasskella 4	Chamaepinnularia 5,6	Nupela 7,8
Valve size	Small (L:8.4–	Small to	Medium to	Small (L:12–27,	Small (L:5–34, W:2–	Small (L:5–29,
	25.2, W:1.6–3.7	medium (L:7–	large (L:50–	W:1.4–3 µm)	12 µm)	W:2–6 µm)
	µm)	78, W:2.5–10	110, W:6.5–15			
		µm)	µm)			
Valve	Bilateral	Dorsi-ventral or	Bilateral	Bilateral	Bilateral	Slightly
symmetry	or slightly	bilateral				asymmetric,
	asymmetric					heterovalvar
Valve shape	Linear	Elliptical or	Linear or	Linear lanceolate	Linear lanceolate,	Linear
	lanceolate	linear lanceolate	broadly		elliptical, rhombical-	lanceolate
			lanceolate		lanceolate or undulate	
Apex	Broadly round	Cuneate, rostrate	Broadly round	Subcapitate or	Subcapitate, capitate	Subcapitate,
	to subcapitate	or subrostrate	or slightly	capitate	or broadly round	capitate or
			cuneate			slightly cuneate
Striae	Not chambered,	İncludes two	Chambered	Not chambered,	Chambered,	Not chambered,
	composed of	kinds of areolae,	with two	composed of two	composed of two	composed
	two rows of	one in valve	alveoli	rows of areolae,	rows of macroareolae,	of elliptic
	macro areolae,	face with broad	composed of	one macroareola	one on valve face	areolae, Areolae
	one on valve	areolae, not	macroareolae	on valve face and	and one on mantle,	transapically
	face and one on	chambered	occluded	one circular on	sometimes circular	elongated,
	mantle	and the other	by small	mantle		external
		marginally	multiseriate			openings of
		chambered	poroids, one			areolae larger
		Composed	on valve face			than internal
		of two,	and the other			openings
		three or four	extending onto			
		transapically	the mantle			
		circle or slit-like				
		broad openings				
		on mantle				
Occlusion in	Hymenate	Absent	Absent	Hymenate with	Covered by vela	Hymenate
external valve				lineolate pores		
face						
Occlusion in	Foriculate	Present (delicate	Absent	Absent	Absent	?
internal valve		porous strip,				
face		called cribra)				
Internal	Straight or	Simple and	Arcuate or bent	Slightly bent to	slightly bent to one	Straight or T-
central raphe	slightly bent to	straight	to one side	one side	side or strongly	shaped ends
endings	one side				deflected	
Internal polar	Simple and	Bent to one side	Deflected to	Simple and	Simple and straight	Simple and
raphe endings	straight	or straight	one side	straight		straight
External central raphe endings	Straight and slightly expanded	Slightly expanded or simple, indistinct	Simple and straight or slightly expanded and slightly bent to one side	Straight	Straight or slightly bent to one side, expanded with small distinct pores	Slightly expanded or straight
External polar raphe endings	Deflected to the same side	Deflected to the same side or straight	Simple and straight or deflected to one side	Deflected to the same side	Deflected to the same side	Deflected to the same side
Helictoglossa	Shallow and present at ends	Shallow and present at ends	Present at ends	Very small and present at ends	Small and present at ends	Shallow and present at ends
Girdle bands	Simple	Porous	Simple	Simple	Simple	?
Habitat	Hypersaline	Freshwater-marine	Marine-brackish	Freshwater	Freshwater or marine	Freshwater
Raphe	Central, externally straight and internally slightly curved	Central or eccentric, straight or biarcuate	Central, straight	Central, slightly curved and short not reaching the center	Central, internally straight or slightly curved, externally straight or slightly arched	Central, slightly curved, heterovalvar (may be reduced or absent on one valve)
Hyaline longitudinal lines or areas	Absent	As a line near the valve margin interrupting the stria and forming a marginal chamber	As a line near the valve margin separating the two alveoli	Absent	As a line near the margin of the valve or as areas (only C. witkowskii), in some species absent	Absent
Central area	Indistinct and small	Indistinct or forming a fascia	Forming a fascia or round, sometimes extended to one side with irregular thickenings	Linear	Swollen or undulate with a fascia or indistinct and small	Asymmetric to apical axis
Axial area	Narrow	Broad, in some species forming a conopeum	Broad	Narrow	Narrow or rather broad	Linear to lanceolate