Netzelia oviformis
Netzelia oviformis
Netzelia oviformis, 76 µm

Netzelia oviformis (Cash, 1909) Ogden, 1979

Diagnosis: Shell elongate ovoid, usually yellow or brown in color; symmetrical and smooth with a broadly-rounded dorsal part; sides curving downwards to the rather narrow and usually tri- or four-lobed mouth which is furnished with an thick wavy lip or collar; shell constructed of flat mineral grains, fragments of diatom frustules and secreted siliceous idiosomes in assorted mixtures to give a smooth surface. Organic cement building units seen as part of general shell matrix, each unit having distinct pores on both inner and outer faces. Single, vesicular nucleus with central nucleolus, one contractile vacuole, cytoplasm not filling shell cavity; pseudopodia numerous simply branched.

Dimensions: Cash 110 µm long and 80 µm broad; other workers: 65-95 µm. My dimensions: 66-85 µm.

Ecology: Between waterplants and in mosses like Sphagnum; usually rare, but sometimes locally abundant.

Remarks: Usually the aperture is 3-5 lobed, but a two-lobed specimen has been reported by Bruce Taylor (pers. comm.). The aperture is surrounded by a thick layer of organic cement which obscures the necklace of small particles. This covering was described as “an expanded wavy collar of thin chitinous substance” by Cash (1905) and clearly figured by Ogden (1980).This rare species is easy to identify. I have seen it in material from the Kromme Rade in Kortenhoef, the Netherlands. In September 2012 I found a very rich population in an isolated forest pond in Baarn. The population occurred in debris on waterplants and all specimens had a four-lobed aperture. Within this population specimens with slender and broad ovoid shells occurred.

Netzelia oviformis
Netzelia oviformis
Netzelia oviformis
Netzelia oviformis
Original drawing of Difflugia oviformis in Cash, Wailes & Hopkinson.
Netzelia oviformis
Netzelia oviformis
Netzelia oviformis, four and five lobed aperture
Netzelia oviformis
Netzelia oviformis
Netzelia oviformis, from Haaksbergen
Netzelia oviformis
Netzelia oviformis
N. oviformis, 85 µm, forest pond, Baarn; right: detail of a collar.
Netzelia oviformis
Netzelia oviformis
Netzelia oviformis, 85 µm, colorless – forest pond, Baarn
Netzelia oviformis
Netzelia oviformis, 85 µm, brownish red – forest pond, Baarn
Netzelia oviformis
Netzelia oviformis
Netzelia oviformis, from Ogden, 1980
Recent posts

Difflugia key bag-shaped

Tests that are bag or thumb-shaped Tests that are bag, finger or thumb-shaped.This group has no taxonomic significance. D. polliciformis D. lemani D. pecac D.

Read More »

Difflugia polliciformis

Difflugia polliciformis, after Van Oye, 1952 Difflugia polliciformis  Van Oye, 1958 Diagnosis: Test more or less thumb-shaped, without clear neck, chitinoid, mainly covered with very

Read More »

Difflugia australis

D. australis after Playfair, 1917 Difflugia australis (Playfair, 1917) Gauthier-Lièvre et Thomas, 1958 Syn.: Difflugia bacillariarum var. australis Playfair 1917 Diagnosis: Test broadly ovate, with

Read More »

Difflugia baradlana

D. baradlana after Varga, 1963 Difflugia baradlana Varga, 1963 Diagnosis: Test ovoid with a very small neck which is about 1/4 of the test length.

Read More »

Difflugia angelica

D. angelica after Gauthier-Lièvre et Thomas, 1960 Difflugia angelica Gauthier-Lièvre et Thomas, 1960 Diagnosis: Test spherical, slightly mammillated. Pseudostome regularly lobed like a star with

Read More »

Difflugia algaephila

D. algaephila after Decloitre, 1977 (l) and Chardez (1980) Difflugia algaephila Decloitre, 1977 Diagnosis: Test ovoid, neatly pointed, with oblique round pseudostome. Dimensions: Length 73-75

Read More »