Thecamoeba striata (Penard, 1890) Schaeffer, 1926

Diagnosis: Stationary amoebae exhibit a knobby appearance, with minimal or no wrinkling. During locomotion, they are flattened, oblong, or elongately elliptical in shape, with the broadest point typically just anterior to the midpoint. The posterior end is usually broadly rounded. In the locomotive form, several parallel dorsal folds, often extending far anteriorly, are visible. The hyaloplasm forms an anterolateral crescent that may extend up to three-quarters of the way toward the posterior. The nucleus contains two to three (occasionally more) nucleolar pieces arranged peripherally. A single, highly deformable contractile vacuole is present, with a diameter of up to 12.5 µm.

Dimensions: According to Page (1977): Length ranges from approximately 28—78 µm (mean 48—52 µm), with a length-to-breadth ratio of 1.1—3.4 (mean 1.4—2.0). Nucleus diameter ranges from 6.5—10.0 µm.

Remarks: This species is most commonly mistaken for T. quadrilineata. It may also be confused with T. similis, as cells of the latter species can adopt an elongated, relatively smooth locomotive form with a few dorsal striae in preparations with low bacterial content. However, T. similis typically transitions to a more characteristic form within a short period.