Microworld

world of amoeboid organisms

Menu
Difflugia species
Fig. 1: a D. pyriformis after Perty, 1849; b D. oblonga after Ehrenberg, 1858; c-d Pyriform tests

 

Difflugia pyriformis group

 

Perty (1849, 1852) described Difflugia pyriformis (Fig. 1a) the shell of which is 140-200 µm long, pyriform or sometimes irregular in shape, and with a rough surface. Since then this species has been subject of many discussions and misinterpretations. Authors considered it being identical with D. oblonga Ehrenberg 1832 (Fig. 1b) and even modified the original description of the latter to fit that of D. pyriformis.

 

Pyriform or pear shaped tests are not rare, but differ in shape and size, ranging from about 60 till over 600 µm. It’s not likely that all these shells belong to one species. However it’s extremely difficult to distinguish between species solely based on light microscopical characters. DNA sequencing can be very helpful here. Traits which might be important to distinguishing between species are:

  • length and breadth of the test
  • L/B ratio
  • diameter of the aperture
  • construction of the pseudostome
  • presence or absence of symbiotic algae
  • relative length of the neck
  • structure of the nucleus
  • cyst formation
  • food

As long as we don’t have sufficient matches between DNA sequences and morphological characters it is nearly impossible to know which species belongs to a specific test.

Difflugia species

 

Difflugia pyriformisup to 483 um: one or more species?

 

Difflugia pyriformis, 284-307 µm – Lemmer, Netherlands
Recent posts

Penardochlamys arcelloides

P. arcelloides – from Penard, 1904 Penardochlamys arcelloides  (Penard, 1904) Deflandre, 1953 Diagnosis: Colorless or very slightly yellowish envelope, bag or cauldron-shaped, very thin, chitinous,

Read More »

Reticulomyxa hannae

R. hannae, plasmodium – photomicrograph Steffen Clauss Reticulomyxa hannae Völcker and Clauß, 2020 Diagnosis: Trophozoites surrounded by a very thin mucous envelope, with slowly moving plasmodia, variable

Read More »

Velamentofex saxonensis

V. saxonensis, feeding (photomicrograph Steffen Clauss) Velamentofex saxonensis Völcker and Clauß, 2020 Diagnosis: Trophozoites ovoid, 30-95 μm, granuloreticulopodia up to 1000 μm long. with a hyaline, thin

Read More »

Velamentofex tyrolensis

V. tyrolensis (photomicrograph Steffen Clauss) Velamentofex tyrolensis Völcker and Clauß, 2020 Diagnosis: Trophozoites ovoid, 98-125 μm, with reticulopodia up to 300 μm long, with a hyaline,

Read More »

Velamentofex berolinensis

V. berolinensis Velamentofex berolinensis Völcker and Clauß, 2020 Diagnosis: Trophozoites ovoid, 50-300 µm, with a hyaline, extremely flexible, membranous test. Nuclei numerous, 11.6-16.2 µm in diameter,

Read More »

Lieberkuehniidae

 Lieberkuehniidae  Siemensma, Holzmann, Apothéloz-Perret-Gentil, Clauß, Voelcker, Bettighofer, Khanipour Roshan, Walden, Dumack and Pawlowski, 2020 Diagnosis: Multinucleate organic-walled monothalamous foraminifera. Test very flexible, elongated to broadly

Read More »