Key to (some) species (after Page, 1988)
| 1 | Outline and general surface fairly smooth; often with several parallel folds extending far anteriorly; normal locomotive form and activity in fresh wet mounts (‘smooth’ species) | 2 |
| – | Surface of stationary amoebae moderately to highly wrinkled, becoming somewhat smoother in locomotion, but most species with rather wrinkled edges and irregular, usually longitudinal dorsal folds; well-extended and active locomotive forms rare on slides under cover glasses (‘rugose’ species) | 3 |
| 2 | Nucleus with a single, central, smoothly contoured nucleolus; L usually c. 35-100 µm, giant forms in some cultures to 170 µm; L/B 1.7; nucleus usually c. 7.5-11.0 µm. | T. quadrilineata |
| – | Nucleus with 2 or 3 (occasionally more) parietal nucleolar lobes; L 30-80 µm; L/B 1.7; no gigantism observed; nucleus 6-10 µm: very similar to T. quadrilineata except in nuclear structure. | T. striata |
| 3 | Nucleolar material in parietal pieces | 4 |
| – | Nucleolar material not parietally arranged | 5 |
| 4 | L usually 60-200 µm, sometimes larger: x L/B c. 1.6-1.7; in locomotion, usually wrinkles around periphery and sometimes fine surface wrinkles extending far forward from more or less wrinkled, sometimes plicate uroid; sometimes small hyaline knobs or scallops on anterior edge; nucleus an elongate ellipsoid, with rather larger parietal nucleolar pieces of various sizes, 14-36 µm. | T. terricola |
| – | L 30-80 µm, often broader than most members of genus (L/B 0.8-1.8); surface moderately wrinkled on stationary amoebae, smoother in locomotion. sometimes with a few dorsal folds converging posteriorly; nucleus usually ovoidal or ellipsoidal with numerous small, parietal nucleolar pieces, 7.7-13.9 µm. | T. similis |
| 5 | L 80-130 µm, x L/B 1.4; sometimes with knobby uroid but not strongly taperedposteriorly; nucleus spherical or ovoid (11.0-15.5 µm), with nucleolar material in coarsely granular central mass, sometimes partly or completely divided into 2 or 3 fragments in centre of nucleus. | 6 |
| – | L approximately as above or slightly larger, with more tendency to form shrivelled uroid on markedly tapered posterior end (outline sometimes triangular); two central, closely apposed endosomal structures in nucleus. | T. verrucosa |
| 6 | Elongated drop-shaped | T. sphaeronucleolus |
| – | Broader locomotive form, spatulate or fan-shaped | T. aesculea |