Testate Amoebae –
Amoebozoa (Part), Stramenopiles (Part), Rhizaria (Part)

Observations on Pyxidicula operculata

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Taxonomic tree according to Lahr et al., 2019 (https://doi.org/10.1016/j.cub.2019.01.078)
and González-Miguéns et al., 2022 (https://doi.org/10.1016/j.ympev.2022.107557)

Amorphea Adl et al., 2012
Amoebozoa Lühe, 1913, renewed definition Cavalier-Smith, 1998
● Tubulinea Smirnov et al., 2005
●● Elardia, Kang et al., 2017
●●● Order Arcellinida Kent, 1880
●●●● Suborder Organoconcha Lahr et al., 2019
●●●●● Family Microchlamyiidae Ogden, 1985
●●●●●● Genus Pyxidicula Ehrenberg, 1838

Pyxidicula operculata (Agardh, 1827) Ehrenberg, 1838

Most likely ID: n.a.

Basionym: Frustulia operculata Agardh 1827

Add’l Synonyms: n.a.

Ogden, Colin G. „Die Feinstruktur der Schale von Pyxidicula operculata, einer aquatischen, steinförmigen Amöbe (Rhizopoda).“ Archiv für Protistenkunde 133.3-4 (1987): 157-164.
“The testate amoeba Pyxidicula operculata was initially described by AGARDH (1827) as a species of the diatom genus Frustulia and later transferred by him (1830) to another diatom genus, Cymbella. It was subsequently placed by EHRENBERG (1834) in his new genus Galionella as G.? (Pyxidicula) operculata, the genus Pyxidicula only later being given status in the name P. operculata by EHRENBERG (1838), although again it was still considered a diatom.”

Sampling date 10/2008.

The lateral view shows an elliptical profile whereas the shape is circular in topview. Pseudopods appear as tapered protuberances of protoplasma. The aperture is almost as wide as the shell diameter, the rim is visible. Dimensions of specimen: 15µm x 20 µm.

The specimen resembles Pyxidicula patens in some morphological aspects, but the shell diameter is only half of the expected value. For further details on the sample shown here, please see Pycidicula spec. in arcella.nl.
Specimens of this sample were molecularly examined by Daniel G. Lahr in 2011 and were shown to belong to the species P. operculata (https://doi.org/10.1371/journal.pone.0022780).

Place name: Pond Suploch, Hiddensee (Germany)
Latitude: 54.538638 Longitude: 13.097802

Microscope Zeiss Universal, camera Olympus C7070WZ.

Scale bars indicate 10 µm (2, 3, 5), 100 µm (6).

Six images.

First:	The cell lived on the neuston, the biofilm on the water surface. The test, the two contractile vacuoles and the nucleus with nucleolus are visible. Diameter of the specimen: 20 µm.
Second:	A group of Pyxidicula living on Hyponeuston, the aquatic area closely attached to the water surface, together with bacteria, which are their prey. On the left the nucleus and the two contractile vacuoles are visible, right to this specimen lies an empty test. The water surface has enough tension so that this testate amoebae can „walk“ on it.
Third:	Synopsis of an empty test and a living cell where focal plane is adjusted to depict the vesicular nucleus with its prominent nucleolus.
Fourth:	Longitudinal section through a shell.
Fifth:	A group of Pyxidicula living in Hyponeuston. Focal plane on nuclei and contractile vacuoles.
Sixth:	Pyxidicula-blooming under the water surface of a little tank in the laboratory.

Please click on < or > on the image edges or on the dots at the bottom edge of the images to browse through the slides!

Place name: Pond Suploch, Hiddensee (Germany)
Latitude: 54.538638 Longitude: 13.097802

Microscope Zeiss Universal, camera Olympus C7070WZ. DOF images.

Sampling date 09/2010. Scale bars indicate 10 µm.

Two images.

Please click on < or > on the image edges or on the dots at the bottom edge of the images to browse through the slides!

Place name: Pond situated in the vicinity of Lake Constance (Germany)
Latitude: 47.734945 Longitude: 9.091097

Microscope Zeiss Universal, camera Olympus C7070WZ. DOF images.

Two images.

Please click on < or > on the image edges or on the dots at the bottom edge of the images to browse through the slides!

Place name: Pond Birkensee near Rödelsee (Lower Franconia, Germany)
Latitude: 49.71819841 Longitude: 10.27807474

Microscope Zeiss Axioplan, camera Canon DSLR.

© Wolfgang Bettighofer,
images under Creative Commons License V 3.0 (CC BY-NC-SA).
For permission to use of (high resolution) images please contact postmaster@protisten.de.

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Observations on Pyxidicula operculata

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