Key to the species of Dictyopteris
| 1 | Fronds very similar to Dictyota species, but nearly wholly prostrate and with midrib; branching irregularly dichotomous | D. repens |
| 1 | Fronds not similar to Dictyota (wider, taller, coarser), not prostrate; with numerous apical cells | 2 |
| 2 | With veinlets visible to naked eye, forming acute angles to the midrib; sporangia or gametangia in linear patches parallel to midrib; blade mostly distromatic from margin to midrib | D. plagiogramma |
| 2 | Veinlets microscopic and faint; sporangia or gametangia in rows starting at midrib and arching downward to lateral margins; blade monostromatic for up to 15 cells from margin, then di-polystromatic to midrib | D. australis |