#1b42

Navicula cocconeiformis

Valves strictly elliptical to almost circular with more or less broadly rounded ends

Puncta more dense (>10-16/10um)

Striae strongly radial

Central area small or absent

Valves more or less rhomboid-lanceolate

Found in sample 1B42

Cymbella subcuspidata

Terminal fissures curved towards dorsal margin

More naviculoid forms, dorsal side a little more convex than ventral side

Valves linear, narrowly elliptical, broadly elliptical or linear-elliptical

Valves broadly elliptical

Striae coarsely punctate

Raphe proximally with shepherd's crook shaped central fissure

Found in sample 1B42

Gomphonema acuminatum

Without distinct longitudinal lines on valve or mantle face

Central area with 1 or 2 stigmata

Valves with 1 stigma in the central area, either a lengthening of the central striae (which are usually short) or in an almost central position (rarely with additional "isolated puncta" distinguishable)

Valves strongly constricted (transapically) above the middle of the valve

Head pole more or less cuneate or drawn out and sharply rounded

Found in sample 1B42