Actinotaenium cucurbita

(Brébisson ex Ralfs) Teiling, 1954

Most likely ID: n.a.

 

Synonym: n.a.

 

Sampling location: Sima Moor (Austria)

 

Phylogenetic tree: Actinotaenium cucurbita

 

Diagnosis:

  • cells almost cylindrical or broad ellipsoidal
  • circular in apical view
  • lateral margings almost straight, tapering to flat convex apices
  • shallow median constriction
  • length 30–50 µm, width 15–25 µm
  • cells 2–2.4 times longer than wide
  • chloroplasts star-shaped with irregular longitudinal ridges
  • one pyrenoid per semi-cell
  • cell wall punctae with 1–2 horizontal rows above isthmus
Actinotaenium-cucurbita
Actinotaenium cucurbita

 I have only ever found Actinotaenium cucurbita in Sima Moor in June 2024. The species was common there. The specimen shown below has a length to width ratio of 2.12 and is therefore in the range of 2.0–2.4 indicated by Lenzenweger (1996). I could not exactly recognize the punctation of the cell wall in the living specimen. It is best visible in empty cells of dead specimens.

Actinotaenium-cucurbita

Fig. 1 a-b: Actinotaenium cucurbita. L = 35 µm. Two focal planes from the Sima Moor found in June 2024. Obj. 40 X.