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.


1 Test oval to flask shape, rigid, chitinoid, clear, completely organic, non–areolar 3
- Test compost of different material 2
2 Test composed of self secreted quadratic plates Quadrulella
- Test composed either of recycled shell plates of small euglyphids or other similar material such as diatom frustules incorporated in the test (plates sometimes covered by very thick organic layer giving the impression of a chitinoid, clear, organic and non structured test) or composed of agglutinated particles as in genus Diffluga 4
3 Test oval elongated, pyriform, flask shaped sometimes with an elongated neck or wedge shaped, totally transparent without structure Hyalosphenia
- Test pyriform, with a lateral indentation at each side, test often organic, totally hyaline, without structure, but sometimes with a (probably self secreted) rough granulated structure (visible by SEM) Alocodera
4 Test pyriform or flask shaped, composed of euglyphid idiosomes embedded in an unstructured organic cement, or often covered with a thick layer of organic cement giving the test a smooth appearance. In the broad view two large (2-5 μm) and conspicuous pores in depressions connected by internal tubes situated at the base of the neck (ca. 2/3 from the fundus of the test) 5
- Test lacking pores in depressions connected by internal tube. Test composed of siliceous plates or diatom frustules, sometimes covered with a thick organic layergiving an organic hyalinous unstructured impression (e.g. in the Nebela collaris s.l. group N. tincta, N. guttata, N. pechorensis, N. flabelululum, cf. or composed of agglutinated particles (unique case of Padaungiella nebeloides 6
5 Test flask-shaped, with an elongated neck. Internal side of neck with pointed protuberances visible in LM as lines of points Certesella
- Test lacking pointed protuberances in the internal side of the neck Porosia
6 Test flask-shaped, oval-elongated, pyriform, neck either absent, short or if long tapering toward the aperture and never clearly separated from the base of the test Nebela
- Test bottle-shaped. Neck elongated, often with approximately parallel sides and always very distinct  7
7 Neck deeply constricted at the junction with the main body of the test Apodera
- No constriction at the base of the neck Padaungiella

Key from Kosakyan, A.



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