Ehrenberg 1837 Category: Monoraphid TYPE SPECIES: Cocconeis
scutellum Ehrenberg Cocconeis is heterovalvar, that is, the
raphe valve ornamentation differs from that of the rapheless
valve. Ornamentation of the raphe valve may differ markedly from
that of the rapheless valve. The valve mantle is narrow in
relation to the valve face, so cells are rarely (if ever) seen
in girdle view. Valves may be flexed, or arched, along the
apical axis forming a 'saddle' shape. Striae are often
uniseriate, but some taxa possess multiseriate striae composed
of loculate areolae. In several taxa, the raphe valve is marked
by a region near the edge of the valve that is ornamented with a
hyaline ring and a more defined mantle than the rapheless valve.
Valvocopula may be closed, or complete, with internal
projections of silica. The genus contains both marine and
freshwater taxa. Living cells have a solitary and adnate habit
of growth. Cells possess a single plastid that is flat and
C-shaped. Species of Cocconeis may be epiphytic on