Key to (some) species (after Page, 1988)

1Outline 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
2Nucleus 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
3Nucleolar material in parietal pieces4
Nucleolar material not parietally arranged5
4L 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
5L 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
6Elongated drop-shapedT. sphaeronucleolus
Broader locomotive form, spatulate or fan-shapedT. aesculea
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