The euglyphids are a prominent group of filose amoebae that produce shells or tests that in most described species is reinforced by siliceous scales, plates, and sometimes spines, but this reinforcement is absent in other species. These elements are created within the cell and then assembled on its surface in a more or less regular arrangement, giving the test a textured appearance. There is a single opening for the long slender pseudopods, which capture food and pull the cell across the substrate. Euglyphids are common in soils, marshes, and other organic-rich environments, feeding on tiny organisms such as bacteria. The test is generally 30–100 μm in length, although the cell only occupies part of this space. During reproduction a second shell is formed opposite the opening, so both daughter cells remain protected. Different genera and species are distinguished primarily by the form of the test. Euglypha and Trinema are the most common. The euglyphids are traditionally grouped with other amoebae. However, genetic studies instead place them with various amoeboid and flagellate groups, forming an assemblage called the Cercozoa. Their closest relatives are the thaumatomonads, flagellates that form similar siliceous tests. Photosynthetic species are found in the genera Paulinella and Placocista. The photosynthetic abilities in Paulinella comes from an event when a cyanobacterium settled permanently within the cell. In Placocista, where a few species have colonies of symbiotic Chlorella living inside them, the relationship is less intimate. The photosynthetic Paulinella are phototrophic, and the photosynthetic Placocista are mixotrophic.

Morphology

[[File:2023 EuglyphidYEpk.svg|center|thumb|upright=2|Representation of a euglyphid1. Siliceous test plate 2. Golgi apparatus; modifies proteins and sends them out of the cell 3. Endoplasmic reticulum, the transport network for molecules going to specific parts of the cell 4. Nucleus 5. Nucleolus 6. Spine 7. Mitochondrion, creates ATP (energy) for the cell 8. Matrix vesicle 9. Matrix 10. Reserve plate 11. Pigment granule 12. Bacterial endosymbiont 13. Contractile vacuole, regulates the quantity of water inside a cell 14. Lysosome, holds enzymes 15. Phagocytic vacuoles with prey 16. Digestive vacuole 17. Large central vacuole 18. Epipodium 19. Apertural collar 20. Retracting filopodium 21. Extended filopodium]]

Phylogeny

Phylogeny based on Chatelain et al. 2013

Taxonomy

Order Euglyphida Copeland 1956 emend. Cavalier-Smith 1997