Key to the species of Dictyota
| 1 | Plants dark chocolate brown, fronds tightly to loosely spiralled (twisted) axes up to 3 mm in diam., terminal dichotomous division about 1 mm in diam | D. acutiloba |
| 1 | Plants medium brown to yellowish, often iridescent when fresh, blades not twisted | 2 |
| 2 | Fronds rarely more than 4 cm long, less than 2 mm at widest, then narrowing abruptly toward apices; on same plant, some portions may be 2 to 3 mm wider than other places | D. ceylanica |
| 2 | Fronds free of turf up to 5 cm long, shorter if in turf; characteristically nearly same width throughout, with truncate apices; branch dichotomies short | 3 |
| 3 | Fronds golden with bluish iridescence until removed from water, often in turf on sides of tide pools; in surface view some superficial cells having L-shaped lenticular thickenings | D. friabilis |
| 3 | Fronds yellowish-green, iridescent, occasionally whole plant with 1-2 twirls, but fronds not twisted; no lenticular thickenings; lateral margins with many proliferations of various lengths and sizes | D. sandwicensis |
