SPECIES starting with "M"

Symmetrical biraphid - Valves are elliptic to linear-elliptic with bluntly rounded ends. Partecta are all the same size. Striae consist of single rows of coarse areolae. Raphe branches are sinuous (not straight).

Symmetrical biraphid - Valve linear-lanceolate with apices protracted and rounded. The raphe is lateral, reverse lateral about midway from the apices to the central area. Striae are radiate and biseriate.

Symmetrical biraphid - Valves are linear-lanceolate to elliptic-lanceolate with subtly protracted and broadly rounded apices, lateral sterna, and partecta of two different sizes. The striae are uniseriate and the raphe is straight, rather than sinuous.

Symmetrical biraphid - Valves elliptic-lanceolate with protracted, broadly rounded apices. The raphe is filiform, becoming lateral at about ½ from the apices to the center. Striae are radiate and distinctly punctate.

Symmetrical biraphid - Valves linear-lanceolate, with margins slightly convex to nearly straight. The apices are bluntly produced. The raphe is straight and filiform, becoming lateral at about ½ the way between the apex and central area. The proximal raphe ends are enlarged. Striae are distinctly punctate and radiate, except at the apices where they are parallel.

Centric - Melosira undulata has large, robust, cylindrical frustules linked in long chains. Valves and mantles are conspicuously ornamented with rimoportulae and striae. A ring of evenly-spaced rimoportulae encircles the mantle near the valve/mantle interface. The mantle is unevenly thickened internally, giving an undulating appearance.

Centric - Cells cylindrical, often forming long chains. Valve face slightly convex, covered with very small spines. Unlike many Aulacoseira species, valves lack areolae.

Araphid - Valves linear-clavate, asymmetric to the transapical axis. Costae are present running transversely across the valves. A narrow sternum extends the length of the valve. A single rimoportula is located near the headpole.

Araphid - Valves are slightly heteropolar, with ovoid to linear-lanceolate margins. Frustules typically attach to one another in long ribbon-like colonies. Transapical costae are mostly perpendicular to the apical axis and number 4-6 in 10 µm. Striae are distinct and number 16-18 in 10 µm.