Lagenodifflugia vas (Leidy, 1874) Medioli and Scott, 1983
Difflugia vas Leidy, 1874
Difflugia pyriformis var. vas Leidy, 1879
Pontigulasia vas (Leidy, 1874) Schouteden, 1906
Zivkovicia vas (Leidy, 1874) Ogden, 1983 (pars)
Diagnosis: Test pyriform, often with a well-marked constriction of the neck, frequently circular in cross-section but sometimes slightly compressed, composed mainly of agglutinated mineral particles bound by an organic cement: aperture terminal, circular: internally the shell is partitioned into two regions by a diaphragm constructed as part of the shell wall but having a single, usually central orifice. Nucleus with numerous nucleoli of different size, the largest ones in the periphery, intermingled with smaller ones; in general nucleoli are smaller towards the center. Zoochlorellae present.
Dimensions: Leidy: 2/5 mm = 400 µm. My measurements: Length 296-358 µm; nucleus 49-54 µm (n=2) .
Ecology: Freshwater, between water plants and in sediment; also in wet Sphagnum. If present, abundant.
Remarks: The original description is of Joseph Leidy (1874): “Test composed of angular quartz particles, generally coarse, shape pyriform, with the neck constricted where it joins the body; fundus obtuse; mouth large, circular. Entosarc bright green from the abundance of chlorophyll granules. Length of test 2/5 mm.; neck one-fourth to one-third the length of the test. Abundant in Absecon Pond, New Jersey.”
Stump (1943) made a study of the nuclear division of the organism. During metaphase eight to twelve “chromosomes” form a well-defined equatorial plate; average time for completion of the division was found to be eighty minutes.
Resembling Difflugia pyriformis in appearance except for the constricted neck.