Thecamoeba striata
(Penard, 1890) Schaeffer, 1926
Most likely ID: n.a.
Synonym: n.a.
Sampling location: Simmelried
Phylogenetic tree: Thecamoeba striata
Diagnosis:
- stationary form broadly oval, not folded
- in locomotion elongated elliptical with several dorsal folds
- length 28–78 µm (commonly 48–52 µm)
- crescent-shape seam of hyaloplasm in flow direction
- spherical nucleus (6.5–10 µm) with 2–3 nucleolar pieces arranged peripherally
- one contractile vacuole, often located posterior
Thecamoeba striata is the most common species of the genus Thecaomeba in my sampling site Simmelried. The typical dorsal longitudinal folds can already be recognized at low magnification, but a reliable determination is only possible with a precise examination of the nucleus, as this is the only distinguishing feature between Thecamoeba striata and the similar species Thecamoeba quadrilineata. In Thecamoeba striata, the nucleolus consists of several pieces that all lie against the nuclear membrane and thus line the nucleus. In contrast, Thecamoeba quadrilineata has a central, spherical nucleolus that is homogeneous and smooth. The fact that these are two valid species, which differ only in their nuclear apparatus, was proven by cultures in which the species-specific characteristics were constantly maintained.
More images and information on Thecameoba striata: Ferry Siemensma-Microworld-Thecamoeba striata
Fig. 1 a-d: Thecamoeba striata. L = 79 µm. A freely gliding specimen. Note the longitudinal folds (LF) on the dorsal side. Nu = nucleus. Obj. 100 X.
Fig. 2 a-d: Thecamoeba striata. L = 73 µm. A second specimen freely gliding specimen. Note the peripheral nucleolus in the nucleus (Nu). CV = contractile vacuole. Obj. 100 X.