#2a66

[diatomsoffinland-blog]

Rhopalodia gibberula

Valves with narrower, steeply sloping dorsal side and broader, less sloping ventral side, the raphe is running on the ridge between the dorsal and ventral sides.

Puncta distinguishable under L/M with high magnification

Fine structure

Ventral edge concave, outline of the valve sickle-shaped

Keel weakly developed, raphe running along the valve edge, barely distinguishable in valve view

Found in sample 2A66

(2/2, p. 442 - keys out p. 184)

[diatomsoffinland-blog]

Eunotia serra

Distal raphe ends end in a shorter or longer curve on the valve surface, valve ends not rostrate

Dorsal edge with two or more pronounced humps

Valves with more than three humps, compare with E. muelleri

Found in sample 2A66

(2/3, p. 522 - keys out p. 76)

[diatomsoffinland-blog]

Pinnularia semicruciata

Striae and transapical ribs narrower

Striae somewhat divergent or not divergent

Valves with moderately broader or narrower central area

Raphe strongly lateral, large forms

Ends sharply narrowing and broadly wedge shaped, middle of the valve not distended or barely so

Central area a single sided fascia, 4-5 striae broad

Found in sample 2A66

(2/1, p. 834 - keys out p. 148)

[diatomsoffinland-blog]

Tabellaria flocculosa

Valve convex in the middle with ends inflated

Edge of the valve with delicate to coarse spinules

Valves less than 10um wide, only a single rimoportula near the middle of the valve

Found in sample 2A66

(2/3, p. 442 - keys out p. 69)