GENERA starting with "g"


Geissleria 6

  1. Annulae present at poles
  2. Isolated punctum present or absent in the central area
  3. Valve elliptical or linear-elliptical with rounded or rostrate ends

Symmetrical biraphid - Geissleria valves are elliptical to linear-elliptical, becoming obtuse, broadly rounded or rostrate at the ends. The striae are comprised of fine lineolate areolae; aerolae 50-80 in 10 ┬Ám. Distinctive annulae are present at the poles. The annulae are comprised of one to four transapical striae that interrupt the typical striae. The raphe is straight and filiform, with straight proximal ends. Terminal raphe ends are...

Gomphoneis 13

  1. Valves clavate, symmetric to the apical axis
  2. Pseudoseptae present
  3. Longitudinal lines may be present
  4. Striae multiseriate

Asymmetrical biraphid - Gomphoneis valves are clavate in both valve and girdle view. Valves are symmetrical to the apical axis. Two distinct groups are currently included within the genus Gomphoneis. One group contains species (including G. herculeana and G. eriense) with multiseriate striae crossed by longitudinal lines and with stigmata. The longitudinal lines are formed by either marginal lamellae or an axial plate, both internal structures...

Gomphonema 16

  1. Valve outline club-shaped
  2. Single stigma present, or absent
  3. Apical pore field present
  4. Striae uniseriate

Asymmetrical biraphid - Valves are symmetric to the apical axis, and asymmetric to the transapical axis. In valve view, valves are club-shaped, or clavate. In girdle view, frustules are wedge-shaped, or cuneate. A stigma may be present on one side of the central area. An apical pore field is present and bisected by the terminal raphe. Striae are uniseriate. Striae are not crossed by longitudinal lines, as in Gomphoneis. Many species grow on...

Gomphosinica 1

  1. Valves club-shaped
  2. Striae composed of 2-3 rows of areolae
  3. Stigma present
  4. Internally, stigma covered by hood
  5. Apical pore field present

Asymmetrical biraphid - Valves are clavate, or club-shaped, in valve view. In girdle view, frustules are cuneate. Striae are composed of 2-3 rows of areolae. Internally, the proximal raphe ends are unilaterally curved. A prominent stigma is present in the central area. Externally, the stigma has a round opening. Internally, the stigma has many small, round openings. An apical pore field is present at the footpole. The pore field has with...

Gomphosphenia 2

  1. Valves cuneate
  2. Axial area broad
  3. Proximal raphe with straight ends

Asymmetrical biraphid - Valves cuneate, with straight or undulate sides. Frustules are never bent or flexed. The raphe is straight and filiform, with straight external terminal fissures (both proximal and distal). Internally, the distal raphe fissure terminates in a helictoglossa. Stigmata are absent. Striae composed of open foramina, which may be obscured externally to give the appearance of ghost striae. Apical porefields, septa and...

Gyrosigma 2

  1. Valve sigmoid
  2. Raphe sigmoid
  3. Striae punctate, punctae form rows perpendicular and parallel to the axes

Symmetrical biraphid - Gyrosigma valves are sigmoid in valve outline. The axial area is narrow and also sigmoid, containing a sigmoid raphe. The striae are comprised of punctate areolae and form rows that are perpendicular and parallel to the apical and transapical axes. The central area is round to elliptical. External proximal raphe ends are deflected in opposite directions from one another. In living cells, two plastids are present....