Microworld

world of amoeboid organisms

Menu
A. spectabilis, drawing after Deflandre, 1928, photographed shell from the Diepveen, Netherlands.

Arcella spectabilis   (Deflandre, 1928) new comb.
Arcella mitrata var. spectabilis Deflandre, 1928
Arcella mitrata pars Leidy, 1876

Diagnosis: Shell commonly slightly wider than high; surface with dimples, varying in number, and regularly arranged. In dorsal view with polygonal contour and slightly rounded corners and more or less concave sides. Aperture with crenulated edge with concentric circle due to the buccal tube. In lateral view, the dorsal surface shows the dimples in several shapes: either a basal row plus a sort of apical pyramid truncated or not or two superimposed basal rows plus an apical pyramid. Apertural side deeply invaginated with a long buccal tube.

Dimensions: Leidy (ex icon.): height 80-90 µm; diam. 86-91 µm; diam. of apertural side 65-74 µm; apertural diam. 25-29 µm; height of apertural tube 15-21 µm.

My measurements: Shell height 85-91 µm, diameter 91-98 µm.

Ecology: Freshwater; in wet Sphagnum. Rare. North America (1879), the Netherlands (2017, 2019)

Remarks: I have found this species for the first time in a peat bog, called Diepveen, the Netherlands, 2017, where I also found A. mitrata which was much larger (120-130 µm). Based on the description of Deflandre (1928) and my own observations I’m convinced that A. mitrata var. spectabilis is a separate species. Later on (2019), I also found this species in other peat bogs, the Ganzenpoel and the Davidsplassen, both not far from the Diepveen and all in the northern part of the Netherlands.

A. spectabilis, after Deflandre, 1928
A. mitrata (l) and A. spectabilis (r), both from the same sample, Diepveen, Netherlands.
Arcella spectabilis
Arcella spectabilis
A. spectabilis, both c. 90 µm high, Dwingeloo, Diepveen
Arcella spectabilis
Arcella spectabilis
A. spectabilis, both c. 90 µm high, Dwingeloo, Diepveen
Arcella spectabilis
Arcella spectabilis
A. spectabilis, Height/Width: 91 X 89 µm (L) and 87 X 97 µm, Dwingeloo, Diepveen
Arcella spectabilis
Arcella spectabilis
A. spectabilis, notice the crenulated edge of the aperture (L).
Arcella spectabilis
Arcella spectabilis
A. spectabilis, from Davidsplassen (l) and Ganzenpoel (r), the Netherlands (2019).
Recent posts

Kibisidytes

K. marinus, after Jepps, 1934 Kibisidytes marinus Jepps, 1934 Diagnosis: Small amoeboid organism occurring in the sea, attached to the surface film or to some

Read More »

Phaeobola

P. aeris from Dumack et al., 2000 Phaeobola Dumack et al., 2000 Diagnosis: Cells roundish to oval shaped. Shell colorless to amber-colored, rough surface, few

Read More »

Rhizaspis armata

R. armata, 68 µm long, excl. spines – Laegieskamp Rhizaspis armata (Lauterborn, 1901) Dumack et al., 2021 Basionym: Pamphagus armatum Lauterborn, 1890 Diagnosis: Theca membranous,

Read More »

Rhizaspis spinosa

The original description with original drawings, Penard, 1890. Rhizaspis spinosa (Penard, 1890) Dumack et al., 2021 Basionym: Trinema spinosum Penard, 1890 Diagnosis: Theca membranous, ovoid

Read More »

Difflugia “pseudoclaviformis”

Difflugia “pseudoclaviformis”, front and side view, 424 µm Difflugia “pseudoclaviformis” Diagnosis: Shell pyriform, compressed, with a more or less pronounced aboral protuberance; shell composed of

Read More »

Difflugia from Lolo Pass

Shells 461-448 µm, stacked image. I found this large en remarkable shells in sediment of a small mountain lake near Lolo Pass, Montana USA. It differs

Read More »

Foraminifer drome

Unknown species, collected from the river Drôme, France, 2021 Unknown species September 2021, I found about ten specimens of an agglutinated foraminifer in a sample

Read More »

Cyclopyxis spec

Cyclopyxis spec., 168 µm Cyclopyxis spec. Diagnosis: Shell circular in ventral and dorsal view, more or less hemispherical in lateral view (height/diameter ≈ 0.5); lateral

Read More »

Difflugia fallax

Difflugia fallax, from Penard, 1902 Difflugia fallax Penard, 1890 Diagnosis: Shell hyaline or yellowish-greenish, black at low magnification, round in cross section, formed of a

Read More »