Microworld

world of amoeboid organisms

Menu
Ovulinata parva
O. parva – from Anderson et al. 1997

Genus Ovulinata Anderson, Rogerson & Hannah, 1997
= Ovulina Anderson, Rogerson & Hannah, 1996

Diagnosis: Test ovoid, small (15 µm), organic, lacking scales or mineral particles. Aperture terminal, round to oval, sometimes with a slightly thickened border. Surface somewhat granular (SEM). Nucleus large, vesicular.
Type species: Ovulinata parva Anderson, Rogerson & Hannah, 1996

Ecology: bacterivorous. Sandy marine sediments. The amoebae grow in a broad range of salinities (fresh to seawater). Known only from collection in Scotland. Possibly overlooked elsewhere because of its small size. Monospecific.

Ovulinata
O. parva, from Tarnawski and Lara, 2015

Ovulinata parva Anderson, Rogerson & Hannah, 1996

Diagnosis: Test ovate, round in cross-section to slightly compressed, organic, hyaline and colorless at first becoming increasingly darker amber colored with age. Aperture terminal oval to round unadorned, or sometimes surrounded by a shallow collar. Pseudopodia hyaline, sometimes branched, long tapered to a point, arising directly from the aperture or from the periphery of a thin web of ectoplasm emergent from the aperture. Nucleus round. Nucleolus central to slightly eccentric, round (1 to 2 µm), densely-staining. Fine structural features: cell body ovoid surrounded by fine fibrillar organic envelope immediately lining the inner surface of the test. Test with scattered small elongate pits (~1 µm in major dimension) forming depressions in the surface, without perforations. Pustule like projections with hyaline interiors, appearing as refractive bodies in bright field light microscopy, may be confused with scales or mineral deposits which are lacking.

Dimensions: Length 15 µm, width 11 µm, nucleus 5 µm (n=20).

Habitat and distribution: Bacterivorous. Sandy marine sediments. The amoebae grow in a broad range of salinities (fresh to seawater). Known only from collection in Scotland. Possibly overlooked elsewhere because of its small size.

Ovulinata parva
O. parva, scale bar 10 µm – from Howe et al. 2011

Ovulinata spec.

Diagnosis: Very small testate amoebae (length: 9.7 µm; width: 7.3 µm), with an ovoid non-compressed transparent test, comparable to the related species Ovulinata parva. Pseudostome slit-shaped, oblique, length 3,2 µm. Test brownish. Filopodia fine, branching.

Ecology: Sediment of mesotrophic water in Crailoo, the Netherlands, 2017 and 2019 (see images and video below). At least, I think it is an Ovulinata species.

Ovulinata
Ovulinata
Right test is turned 90°
Ovulinata
Ovulinata
Ovulinata
Ovulinata
Ovulinata
Ovulinata
Ovulinata
Ovulinata
All from Crailoo, the Netherlands, 2017 and 2019

Below a specimen that might be an Ovulinata species; also from Crailoo, Netherlands, 2020

Ovulinata
Ovulinata
Ovulinata
Specimen from Crailoo, the Netherlands, 2019
Recent posts

Euglypha bryophila

Euglypha bryophila, after Brown, 1911 (L), from Ecuador (R) Euglypha bryophila  Brown, 1911 Diagnosis: (Original description) The test is very regular in form and subject

Read More »

Vernalophrys

(A) A Scenedesmus cell (arrow) is engulfed by a trophozoite. (B) Several Scenedesmus cells adhere to the surface of a plasmodium that has numerous vacuoles

Read More »

Actinosphaeridium spec.

Actinosphaeridium spec. Diagnosis: Cell surrounded by a membranous shell, with an outer mucous layer. Filopodia with granules, sometimes branching. Cell stalked. Ecology: I found this

Read More »

Euglyphidion

Euglyphidion enigmaticum – after Bonnet, 1960 Genus Euglyphidion Bonnet, 196 Diagnosis: Shell hyaline, ovoid, pseudostome circular or slightly elliptical. Shell loosely covered with two types of

Read More »

Leptomyxa spec.

Leptomyxa sp., slowly retracting in response to the light of the microscope Leptomyxa sp. Diagnose: This is a very large amoeba which I found in

Read More »

Zivkovicia spec.

Zivkovicia spec., 200 µm long; the right image is viewed through the aperture Zivkovicia spec.  Diagnosis: Shell pyriform, circular in oral view, with a clear

Read More »