Key to Euglypha species
| 1 | Fundus with a tuft of spines (Fig. 1) | 2 |
| – | Fundus without spines or when present spines not in a tuft | 4 |
| 2 | Fundus with 1-2 spines, shell 100-140 µm (Fig. 1e) | E. mucronata |
| – | Fundus with a tuft of 1-8 spines, shell < 80 µm | 3 |
| 3 | Shell with somewhat concave sides (Fig. 1a-c) | E. cristata |
| – | Shell ovoid, slightly compressed (Fig. 1d) | E. bryophila |
Fig. 1: a-c E. cristata b var. major d E. bryophila e E. mucronata
| 4 | Shell usually with spines | 5 |
| – | Shell without spines | 10 |
| 5 | Spines are elongated tapering body scales | 6 |
| – | Spines are not part of body scales | 9 |
| 6 | Spines much longer than the scales | 7 |
| – | Spines about as long as the scales | 9 |
| 7 | Shell more or less broad ovoid, almost spherical | E. cabrolae |
| – | Shell elongated ovoid | 8 |
| 8 | Shell with few long spines near the aperture (Fig. 2a) | E. brachiata |
| – | Shell with some long spines near the fundus (Fig. 2c) | E. acanthophora |
| 9 | Mid-body region with some randomly distributed pointed body plates. | E. dickensii |
| – | Fundus region with sharply pointed body plates | E. penardi |
Fig. 2: a E. brachiata b E. scutigera c E. acanthophora d-e E. tuberculata
| 10 | Shell ovoid, in cross-section circular | 11 |
| – | Shell ovoid or pyriform, in cross-section more or less compressed | 13 |
| 11 | Shell small, < 30 µm | E. laevis |
| – | Shell > 50 µm | 12 |
| 12 | Scales oval (Fig. 2e) | E. tuberculata |
| – | Scales pointed, scutiform (Fig. 2b) | E. scutigera |
| 13 | Shell ovoid, slightly compressed, without spines (Fig. 3e-f) | E. rotunda |
| – | Shell oviform or pyroid, usually with spines | 14 |
| 14 | Spines long | 15 |
| – | Spines short | 16 |
| 15 | Spines like needles, limited to the edge of the shell | E. filifera |
| – | Spines usually lanceolate, but not always clearly visible; spines limited to the edge and the posterior end of the shell. | E. compressa |
Fig. 3: a–d E. strigosa c var. glabra e–f E. rotunda
| 16 | Spines usually numerous, distributed all over the shell surface; Apertural scales clearly larger than the shell scales, about twice as wide; aperture usually round or slightly oval | E. ciliata |
| – | Spines usually short and numerous, distributed all over the shell surface; Apertural scales about the same size as the shell scales | E. strigosa |
| Key based on Hoogenraad en de Groot, 1940, and Edward Mitchell, 2003 | ||