Deuteramoeba algonquinensis (Baldock, Rogerson & Berger, 1983)
Diagnosis: Locomotive form typically polypodial, without any ridges. Anterior hyaline caps frequently fill with advancing granuloplasm. Relatively small posterior morulate uroid. Cytoplasm with few to many crystals, most as paired inclusions, some as bipyramidal crystals. Nucleus more or less spherical with nucleolar pieces of varying size, most parietal, some in interior of nucleus. No cysts observed.
Dimensions: Literature: moving cells about 80 µm in length. My measurements: length 55 to 100 µm, nucleus 7.2–10 µm.
Ecology: Fresh water. Canada, France, Netherlands. I found this species in submerged Sphagnum in the Laegieskamp and in mesotropic water in Crailoo, both in the Netherlands and the river Jointe in Southern France. It came up in a wet mounts kept in a moist chamber.
Remarks: The nucleus is a bit hard to see, but in phase contrast it is very clear. Two or three globular nucleolar pieces are present in the interior part, smaller pieces lay in the perifery.
A New Species of Fresh-Water Amoeba: Amoeba algonquinensis n. sp. (Gymnamoebia: Amoebidae)
B. M. Baldock, Andrew Rogerson and Jacques Berger
The amoeba (hereafter termed Amoeba algonquinensis) was observed to settle very rapidly in hanging-drop preparations. However, cells did not adhere well to glass. Floating forms were characterized by their short radiating pseudopodia which were granular for most of their length and not strongly tapering. Actively locomoting amoebae were typically polypodial, but with only one pseudopodium being dominant at any one time. The pseudopodial tips were hemispherical with a hyaline cap which was rapidly filled by advancing granuloplasm. At initiation of locomotion, the amoeba often appeared palmate. A morulate uroid commonly formed in actively locomoting individuals. The lengths (mean ± 95% confidence limits) of 50 active individuals from two clones (one for each sampling date) were statistically identical at 86 ± 12 µm and 75 ± 10 µm, respectively.
Amoeba algonquinensis is uninucleate with a spherical granular nucleus. The nuclear diameters (mean ± 95% confidence limits) derived from the same two clones were 9.5 ± 0.3 µm and 8.2 ± 0.3 µm, respectively, indicating significant interclonal variability of this attribute.
Crystals, approximately 2 µm long, occurred throughout the cytoplasm. These did not resemble the bipyramidal crystals reported for P. fasciculatum by Page & Baldock (1980). Amoeba algonquinensis was observed to feed on fungal spores, cysts, and trophic H. vermiformis, as evidenced by the contents of its food vacuoles and direct observation of actively feeding individuals.
The behavior of the contractile vacuole complex was the same as that observed in A. proteus and Thecamoeba quadrilineata Carter, 1856 (see Patterson, 1981). The maximum diameter of the contractile vacuole was 8 µm (n = 10) with an emptying time of 85 sec (range, 46-199 sec).