Family Hyalospheniidae Schultze, 1877 emend. Kosakyan and Lara, 2012

Diagnosis: The test is rigid, colorless or yellowish-brown, flask-shaped, oval or pyriform, dorso-ventrally compressed. The shell is either entirely self secreted (e.g. Hyalosphenia) composed of an organic matrix, or with addition of self secreted siliceous plates (Quadrulella) or recycled shell plates of small euglyphids or other similar material such as diatom frustules incorporated in the test. The pseudostome is terminal and bordered by a thin organic collar.

├── Yes → 2
└── No → Test chitinoid, clear, fully organic → 4

2. Test composed of self-secreted quadrangular plates?
├── Yes → 3
└── No → Test composed of recycled plates (euglyphids, diatoms) or agglutinated particles → 5

3. Lateral margins distinctly compressed, forming a thick hollow keel?
├── Yes → Mrabella
└── No → Quadrulella

4. Test oval-elongated, pyriform or flask-shaped, fully transparent, without structure?
├── Yes → Hyalosphenia
└── No → Test pyriform with lateral indentations, hyaline, sometimes granular → Alocodera

5. Test with two lateral horns pointing posteriorly?
├── Yes → Cornutheca
└── No → 6

6. Two lateral depressions with large invaginated pores (2–5 μm) connected by internal tubes?
├── Yes → 7
└── No → 8

7. Inner neck wall with pointed protuberances (visible in LM as rows of dots)?
├── Yes → Certesella
└── No → Porosia

8. Test with a distinct keel?
├── Yes → 9
└── No → 10

9. Keel flat?
├── Yes → Planocarina
└── No → Keel hollow and tuberous → Gibbocarina

10. Test with conspicuously elongated neck?
├── Yes → 11
└── No → 12

11. Neck deeply constricted at its base?
├── Yes → Apodera
└── No → Padaungiella

12. Test flask-shaped, oval-elongated or pyriform; neck absent, short, or long but not clearly separated?
├── Yes → 13
└── No → Distinct neck, margins tapering toward aperture → Longinebela

13. Pseudostome strongly convex?
├── Yes → Alabasta
└── No → Nebela

References: Kosakyan, A., Heger, T.J., Leander, B.S., Todorov, M., Mitchell, E.A.D. and Lara, E.: COI Barcoding of Nebelid Testate Amoebae (Amoebozoa: Arcellinida): Extensive Cryptic Diversity and Redefinition of the Hyalospheniidae Schultze – Protist 163, issue 3, 415-434, 2012

Kosakyan, A., Gomaa, F., Lara, E. and Lahr, D.J.G. : Current and future perspectives on the systematics, taxonomy and nomenclature of testate amoebae – European Journal of Protistology, 2016