SPECIES starting with "o"


Odontidium hyemale

Fragilaria hyemalis
Candollella hyemalis
Diatoma hyemale

  1. Valves narrow, lanceolate
  2. Spines present
  3. Sternum lanceolate, distinct
  4. Costae parallel to slanted
  5. Rimoportula present

Araphid - Valves are narrow and lanceolate, with broadly rounded apices. Costae are parallel to diagonal, numbering 3-5 in 10 um. The axial area in linear to lanceolate, increasing in breadth as cells decrease in size. The sternum is distinct and intrudes into apical porefields at both ends. Spines are present. A single sub-apical rimoportula is positioned at one apex.

Odontidium mesodon

  1. Valves elliptic-lanceolate with rounded ends
  2. Valves 6-12 µm wide
  3. Transapical costae 3-6 in 10 µm
  4. Rimoportula single, near apex

Araphid - Valves elliptic-lanceolate, with rounded apices. Transapical striae and costae are visible in the light microscope.

Orthoseira roeseana

  1. Cells heavily silicified
  2. Marginal spines conical or flattened
  3. Carinoportulae 2-5
  4. Cells joined in filaments

Centric - Cells are heavily silicified, large and possess deep mantles. They are adjoined face-to-face by regularly spaced marginal spines. On the valve face, a small central area contains 2-5 carinoportulae.

Oxyneis binalis

Tabellaria binalis

  1. Valves panduriform
  2. Septa present
  3. Apices broady rounded

Araphid - Valves are small and panduriform, with broadly rounded apices. Septa are present.

Oxyneis binalis var. elliptica

  1. Valves elliptic
  2. Septa present
  3. Stria parallel to slightly radiate

Araphid - Valves small and elliptic. Striae are parallel at the valve center, becoming radiate at the apices.