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Thecamoeba aesculea Kudryavtsev and Hausmann, 2009

Diagnosis: Measured length of the locomotive form 70-119 µm (average 101.5 µm) (n = 60); breadth – 56-117.5 µm (average 80.4 µm); length : breadth ratio – 0.81-1.93 (average 1.29). Spatulate during locomotion, sometimes slightly posteriorly tapering and almost fanshaped. Dorsal surface with 2-5 longitudinal folds and numerous irregular wrinkles, especially in the uroidal part. Single vesicular nucleus 16-22 µm in diameter (average 18.5 µm); spherical central non-homogeneous nucleolus 7.5-14.4 µm in diameter (average 10.4 µm) (n = 35).
Ultrastructure: Glycocalyx up to 33 nm thick, consisting of a basal electron-dense layer 8-10 nm thick and a less dense outer layer about 10-15 nm thick, separated from the basal layer by an 8-10 nm thick electron-transparent space.

Observed habitat: Dry epiphytic mosses and bark surface of Aesculus hippocastanum in Saint-Petersburg, northwestern Russia.

Remarks: Almost identical to Th. sphaeronucleolus in the size, ultrastructure of nucleus and cytoplasm, but differs from the former type strain of this species (CCAP 1583/3) in having a broader locomotive form, spatulate or fan-shaped, rather than elongated drop-shaped; also differs in the structure of the glycocalyx. Slightly resembles Th. similis, but differs from this species in the structure of the nucleus and glycocalyx.

Literature: Kudryavtsev and Hausmann, 2009

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