Haplotaenium rectum
(Delponte) Bando, 1988
Most likely ID: n.a.
Synonym: Pleurotaenium rectum
Sampling location: Schwemm Moor (Austria)
Phylogenetic tree: Haplotaenium rectum
Diagnosis:
- semi-cells straight, subcylindrical, slightly tapered to the apices
- with distinct basal inflation
- length 200–350 µm, width 18–23 µm
- apices smooth, flatly rounded, sometimes with few warts
- chloroplasts several longitudinal ribbons
- pyrenoids scattered in chloroplasts
- 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 rectum was therefore transferred to the genus Haplotaenium by Bando (1988).
I found Haplotaenium rectum in the Schwemm Moor in Austria. The species is easily recognizable by its approximately cylindrical half-cells with parallel sides. Each half-cell has a basal thickening. The apices are broadly rounded and smooth. Only very rarely are a few warts found. The chloroplasts are split into longitudinal bands in which the pyrenoids are scattered.
The similar species Pleurotaenium trabecula is larger (350–550 µm), very often slightly curved, and the apices have a distinct thickening.
Fig. 1 a-b: Haplotaenium rectum. L = 255 µm. Two focal planes f a specimen in DIC. Obj. 60 X.
Fig. 2 a-b: Haplotaenium rectum. L = 255 µm. The same specimen as shown in fig. 1 a-b in brightfield illumination. Obj. 60 X.
Fig. 3 a-b: Haplotaenium rectum. A semi-cell in detail. BI = basal inflation, Chl= ribbon-shaped chloroplasts, PY = pyrenoids. Obj. 100 X.