Rotíferos de los sedimentos del río Cinaruco

Checklist of testate amoebas of Venezuela (Decloitre, 1963)

Decloitre (1963) recognizes 5 species of Arcella in Venezuela. As far as I know, there are no other species checklists of testate amoebas of Venezuela. Decloitre (1963) listed a total of 76 species of testate amoebas species for Venezuela in 15 different genera. The following is the list of species for the genus Arcella.

Genus: Arcella Ehrenberg

Arcella conica Ehrenberg
Arcella hemisphaerica Perty
Arcella hemisphaerica var gibba Deflandre
Arcella lobostoma Deflandre
Arcella polypora Pénard


Decloitre, L. 1963. Rhizopodes Thécamoebiens du Vénézuéla. Proceedings of the Zoological Society of London 141(3): 497-514.

Arcella sp4

Specimen #25312-313:
Diameter shell: 100.8 µm
Diameter aperture: 36.5 µm
Height shell: 157.4 µm
Bucal depth: 9.2 µm

At first I believed this specimen to be Arcella mitrata var pyriformis but if you see on pic 25313, there is no crenulations on the aperture. Unfortunately I have no pictures for the apical view.

Arcella sp3

Specimen #25310-311:
Diameter shell: 160.3 µm
Diameter aperture: 48.7 µm

This specimen is similar to Arcella vulgaris var. undulata but the apreture is crenulated.

Arcella vulgaris f. undulata? Deflandre

Specimen #13854-856:
Diameter shell: 117.4 µm
Diameter aperture: 23.9 µm

Specimen #24962-963:
Diameter shell: 151.0 µm
Diameter aperture: 28.3 µm

Arcella mitrata? Leidy

Specimen # 24973-974:

Diameter shell: 113.2 µm

Diameter aperture: 32.5 µm

Height shell: 115.8 µm

Bucal depth: 13.1 µm

Specimen #24975:
Diameter shell: 115.7 µm
Diameter aperture: 37.4 µm
Height shell: 127.2 µm
Bucal depth: 13.4 µm

Specimen #24971:
Diameter shell: 114.2 µm
Diameter aperture: 33.4 µm
Height shell: 117.4 µm
Bucal depth: 13.7 µm

Arcella mitrata cf pyriformis? Deflandre

Specimen # 25331:
Diameter shell: 125.8 µm
Diameter aperture: 40.5 µm
Height shell: 135.6 µm
Bucal depth: 13.2 µm

Specimen # 25316:
Diameter shell: 121.4 µm
Diameter aperture: 42.7 µm
Height shell: 134.3 µm
Bucal depth: 9.6 µm

This two specimens seem to be Arcella mitrata var pyriformis but they are not tall enough. It seems to be an intermediate form between A. mitrata and A. mitrata var pyriformis.

Arcella cf. mitrata var pyriformis? Deflandre

Specimen #25220-221:
Diameter shell: 112.5 µm
Diameter aperture: 40.5 µm
Height shell: 147.1 µm
Bucal depth: 15.4 µm

This specimen looks like Arcella mitrata var pyriformis Deflandre 1928. Unfortunately, I do not have a picture showing the apical view.

Arcella gibbosa var levis? Deflandre

Specimen #25517:
Diameter shell: 93.5 µm
Diameter aperture: 37.2 µm
Height shell 68.1 µm
Bucal depth: 12.1 µm

Arcella costata var angulosa? (Perty) Playfair

Specimen #25356-358:

Diameter shell: 110.3 µm

Diameter aperture: 32.3 µm

Height shell: 68.4 µm

Bucal depth: 24.1 µm

Arcella costata Ehrenberg

Specimen #25602-604 (left):

Diameter shell: 108.0 µm

Diameter aperture: 37.4 µm

Height shell: 57.0 µm

Specimen #25602-604 (right):

Diameter shell: 105.8 µm

Diameter aperture: 38.1 µm

Arcella sp2

Specimen # 22187:
Diameter shell: 91.4 µm

Specimen # 21892:
Diameter shell: 95.5 µm

Diameter aperture: 24.5 µm

Specimen # 20577:

Diameter shell: 112.9 µm

Specimen # 20598:
Diameter shell: 104.1 µm

I could not measure the diameter of the aperture for some of the specimens. Unfortunately, all these specimens were only photographed on one side (apical view). For now on I will try to photograph all the necessary diagnostic taxonomic characters and all the possible views.

I think all these specimens are similar to Arcella costata. I posted Specimen #20577 earlier. It appears in a picture next to another specimen that I called Arcella megastoma.

Arcella sp1

Diameter shell: 100.8 µm
Diameter aperture: 33.6 µm

These three pictures were taken on the same specimen. I did not know how important is to take pictures of all sides of testate amoebas. It is a shame that I have only pictures showing the apical views of a lot of testate amoebas. I started taken pictures of all sides of these organisms a month ago. The three pictures I am showing here were one of my first attempts to have a complete series of all sides of any specimen. Although these pictures are not very good (I failed placing testate amoebas in the right position) at least they could be helpful for a preliminar identification.

In this specimen, I can barely see a crenulated aperture, but because the shape of the test, I could not say anything conclusive about its identification. This specimen is similar to Arcella leidyana Deflandre 1928 but with a smaller and less tall test.

Arcella crenulata? Deflandre

Specimen #21380:
Diameter shell: 100.2 µm
Diameter aperture: 32.3 µm

Specimen #7386:
Diameter shell: 109.5 µm
Diameter aperture: 24.9 µm

Specimen #12094:
Diameter shell: 143.3 µm
Diameter aperture: 26.5 µm

Arcella costata? Ehrenberg

Specimen #25054:
Diameter shell: 101.1 µm

Specimen #22491:
Diameter shell: 108.8 µm
Diameter aperture: 30.5 µm

Specimen #21041:
Diameter shell: 97.6 µm
Diameter aperture: 29.9 µm

Specimen #10864:
Diameter shell: 121.8 µm
Diameter aperture: 34.6 µm

Arcella discoides? Ehrenberg

Specimen #7560:
Diameter shell: 101.7 µm
Diameter aperture: 34.2 µm