Microworld

world of amoeboid organisms

Menu
Arcella mitrata
A. mitrata, 133 µm high

Arcella mitrata  Leidy, 1876

Diagnosis: Shell balloon-shaped or polyhedral; height more or less the same as the diameter of the base; aperture circular, crenelated and usually averted within inverted funnel; protoplasmic body spheroidal, with ‘neck’ to aperture and cytoplasmic strands to test; six or more slender lobopodia.

Dimensions: Shell 100-162 µm high, 100-180 µm in diameter. My measurements: height 80-200 µm (mean 139 µm), 119-218 µm in diameter (mean 144 µm).

Ecology: Freshwater, in submerged Sphagnum and Utricularia. Rare.

Remarks: I have found this species in oligothrophic and mesotrophic shallow ponds, the bottom covered with sand and/or Sphagnum. Earlier reports for the Netherlands were given by Hoogenraad and De Groot, 1940.

Dutch locations: Baarn (Groeneveld); Hilversum (Bluk); Harskamp (Loofles); Dwingeloo (Diepveen); Fochteloërveen; Haaksbergerveen; Nunspeet (fen); Huizen (fen); Eindhoven (Strabrechtse heide, Wim van Egmond).

Arcella mitrata
Arcella mitrata
Shells 122 um  and 127 µm high, Diepveen, Dwingeloo
Arcella mitrata
Arcella mitrata
Arcella mitrata, 141 µm high (Groeneveld) and 80 µm high, Mittermoor, Tirol, Austria
Arcella mitrata
Structure of a shell (Leitz, 100X Phaco)
Arcella mitrata
Arcella mitrata – ventral view
Arcella mitrata
Arcella mitrata, living specimen
Arcella mitrata
Arcella mitrata, living specimen
Arcella mitrata
Arcella mitrata, 135 µm, from the Loofles, Harskamp
Arcella mitrata
Arcella mitrata, with crenulate aperture
Arcella mitrata
Arcella mitrata, Fochteloërveen
Arcella mitrata
Arcella mitrata
A. mitrata, 135 µm high, Nunspeet, and 113 µm, Huizen, both in the Netherlands
Recent posts

Apolimia

A. rotundistoma, from Korganova, 1987 Genus Apolimia Korganova, 1987 Diagnosis: Shell ovoid, quite large, opaque, round in cross section, densely covered with round or oval

Read More »

Erugomicula

E. bidens, 315 and 270 µm, Naardermeer, the Netherlands Genus Erugomicula Nasser, Gregory, Singer, Patterson and Roe, 2021 Typespecies: Erugomicula bidens (Penard, 1902) Diagnosis: laterally-compressed,

Read More »

Erugomicula bidens

Two shells from the same sample, 310 µm (Naardermeer, Netherlands) Erugomicula bidens (Penard, 1902) Basionym: Difflugia bidens Penard, 1902 Diagnosis: Test ovoid, compressed in cross-section,

Read More »

Cylindrothecina

Infraorder Cylindrothecina González-Miguéns et al., 2022   Diagnosis:  can be diagnosed by its specific sequences of the mitochondrial and nuclear DNA  markers (COI, NADH and

Read More »

Organic-walled species

Specimen with an optical cross-section of the peduncle (left) Organic-walled species Diagnosis: Multinucleated organic-walled monothalamous foraminifera. Test spherical to oval shaped, with a hyaline, flexible,

Read More »

Velamentofex tyrolensis

V. tyrolensis, two specimens Velamentofex tyrolensis Völcker and Clauß, 2020 April 2022, I found two specimens in a sample from the pond in Crailoo, Netherlands. I could

Read More »

Raphidiophrys spec. nov.

Raphidiophrys n. sp. Raphidiophrys n. sp. Diagnosis: Plate-scales canoe-shaped, elongated, with tapering, rounded poles, slightly curved upwardly. Light microscopically, these plate-scales show a clear rim;

Read More »

Lacogromia spec. Naardermeer

Lacogromia sp., Naardermeer, the Netherlands, 2022 (n=nucleus) Lacogromia sp. Six living specimens were found in an old sediment sample from a freshwater ditch in nature

Read More »

Sphenoderia rhombophora

S. rhombophora , after Bonnet, 1966 Sphenoderia rhombophora Bonnet, 1966 Diagnosis: Test hyaline, ellipsoidal, very slightly compressed. Fundus relatively narrow. Pseudostome largely truncated. Neck very

Read More »

Sphenoderia ovoidea

S. ovoidea , after Jung, 1942 Sphenoderia ovoidea Jung, 1942 Diagnosis: Shell with four layers of plate-scales. Distinguished from S. fissirostris by the ovoid tapering

Read More »