Difflugia urceolata Carter, 1864
Diagnosis: Test large, broad ovoid or spherical. Aperture circular, large; with a more or less pronounced recurved collar, extending as a broad rim. Test composed of mineral grains or diatom frustules, often mixed, cemented together with organic material. In sphagnum the test can be nearly completely chitinous, due to lack of mineral material. Multinucleate, 8-60 nuclei; nuclei granular. Test generally without spines, but a variety, D. urceolata var. olla Leidy, possesses a few short stubby spines developed from the fundus.
Dimensions: in literature 150 – 550 µm long; Ogden (1980) 137 – 171 µm (n=26). My observations: 245 – 280 µm, nuclei usually 20 – 30.4 µm.
Ecology: in ooze of ditches, ponds, and water with sphagnum contact. Sometimes abundant.
Remarks: In cells which I squeezed for counting and measuring the nuclei I usually found 10 – 20 nuclei per specimen. Nuclei are difficult to count, because some are hidden by the xenosomes. Once I found nuclei which were larger than average and showed a different structure (Fig. 2, left). Penard (1902) gives an average of 40 – 60 nuclei per specimen, with diameters varying between 15 and 26 µm.