Haplotaenium minutum
(Ralfs) Bando, 1988
Most likely ID: n.a.
Synonym: Pleurotaenium minutum
Sampling location: Determoor (Austria), Sima Moor (Austria)
Phylogenetic tree: Haplotaenium minutum
Diagnosis:
- cells almost cylindrical, slightly tapered toward the ends
- length 60–160 µµ
- truncate apices smooth, slightly rounded, ornamentation absent
- base of the semi-cells without or a slightly inflation
- two chloroplasts with 3–6 longitudinal ridges
- 2–10 pyrenoids per chloroplast
- cell wall smooth, very delicate punctate
The genus Haplotaenium differs from the genus Pleurotaenium by the absence of a terminal vacuole, axially oriented chloroplasts and zygospores, which have conical protuberances. Pleurotaenium minutum was therefore transferred to the genus Haplotaenium by Bando (1988).
I have only found Haplotaenium minutum in the Determoor (May 1996) and the Sima Moor (June 2024). The population in the Sima Moor was very rich in specimens, two of which are shown below.
The cells can be recognized even at small magnifications by their slender, cylindrical shape. At the base, the half-cells show no or only minimal thickening. The flattened apices, which are slightly rounded at the corners, show no ornamentation. The cell wall is colorless and was completely smooth in my population, without pores.
Fig. 1 a-c: Haplotaenium minutum. L = 100 µm. Three focal planes of a medium sized specimen. Nu = nucleus, PY = pyrenoids. Obj. 100 X.
Fig. 2 a-b: Haplotaenium minutum. L = 124 µm. Two focal planes of a second specimen. Obj. 100 X.