Key to Danish species of Arcyria F.H. Wigg.
| 1 | Spores 9-12 μm in diam. The capillitium attached only at base of calyculus. Sporocarps rusty red to orange red, fading to pale ochraceous. | A. ferruginea Saut. |
| 1' | Spores 6-9 μm in diam. | 2 |
| 2 (1) | The capillitium attached only at base of calyculus (can be removed as an entity). | 3 |
| 2' | The capillitium attached at base as well as on the side of the calyculus. | 9 |
| 3 (2) | Sporocarps yellow to ochraceous yellow. Capillitium expanding into cylindrical plume at maturity. | A. obvelata (Oeder) Onsberg |
| 3' | Sporocarps with reddish colours. | 4 |
| 4 (3) | Sporocarps greyish rose, fading to dull beige. Capillitial net wide-meshed. | A. incarnata (Pers. ex J.F. Gmel.) Pers. |
| 4' | Sporocarps bright red to copper-coloured, fading to brownish red. | 5 |
| 5 (4) | Sporocarps ± globose or somewhat obovoid. Apical part of peridium long persistent, eventually breaking away in flakes. | A. helvetica (Meyl.) Neubert, Nowotny & K. Baumann |
| 5' | Sporocarps elongated, ± cylindrical, upright or drooping and entangled. Apical peridium completely evanescent or remaining as a very thin, ± iridescent membrane. | 6 |
| 6 (5) | Sporocarps copper-coloured, entangled. Often with flakes of the thin and ± shining peridium still attached. Capillitium short cylindrical, ornamentation mostly including spiral bands. | A. stipata (Schwein.) Lister |
| 6' | Sporocarps red. No remnants of peridium except calyculus. The capillitium expanding into lax plume. | 7 |
| 7 (6) | Capillitial ornamentation of spines up to ca. 3 μm long. | A. oerstedtii Rostaf. |
| 7' | The capillitium with short spines, warts, rings and half-rings or ridges, occasionally with a faint net-ornamentation. | 8 |
| 8 (7) | The capillitium with short spines, warts half-rings and ridges, occasionally with a faint net-ornamentation. Sporocarps red to carmin red. | A. affinis Rostaf. |
| 8' | Capillitial ornamentation only of rings and half-rings. Sporocarps coral red. | A. major (G. Lister) Ing |
| 9 (2) | Sporocarps greyish rose to red, fading to beige or reddish brown. | 10 |
| 9' | Sporocarps greyish white to ochraceous, rarely with a greenish tint. | 12 |
| 10 (9) | Sporocarps greyish rose, fading to beige. Capillitium notably fine-meshed, unelastic. | A. minuta Buchet |
| 10' | Sporocarps orange red to carmin-red, fading to reddish brown. | 11 |
| 11 (10) | Sporocarps usually more than 2 mm high, often in large clusters, carmin-red, more rarely very bright red. | A. denudata (L.) Wettst. |
| 11' | Sporocarps less than 1.5 mm high, in small groups of up to 10-15, bright orange red. | A. insignis Kalchbr. & Cooke |
| 12 (9) | Sporocarps ochraceous yellow, spherical to ovoid. Capillitium wide-meshed, with ridges and warts, ornamentation uniform throughout. | A. pomiformis (Leers) Rostaf. |
| 12' | Sporocarps greyish, occasionally with greenish tint. | 13 |
| 13 (12) | Sporocarps greyish white, grey to greyish ochraceous. Short cylindrical to obovoid. Capillitium fine-meshed, with rather close-set spines, in basal parts almost smooth and with thicker tubules. | A. cinerea (Bull.) Pers. |
| 13' | Sporocarps pale greyish green, cylindical. The capillitium with scattered spines, occasionally with irregular net- or spiral-ornamentation. | A. glauca A. Lister |