Key to the species of Bolusiella
| 1. | Leaves not deeply sulcate on upper surface | 2 |
| 1a | Leaves deeply sulcate on upper surface | 5 |
| 2. | Pouch-like outgrowth at the base of the lower sepals and floral bract as long as the flower | 3 |
| 2a | Base of the lower sepals without outgrowth and floral bract strictly smaller than the flower | 4 |
| 3. | Base of the inflorescence straight, spur 1.2 mm or longer | Bolusiella maudiae |
| 3a | Base of the inflorescence fractiflex, spur up to 1.1 mm | Bolusiella fractiilexa |
| 4. | Leaves with rounded apex | Bolusiella zenkeri |
| 4a | Leaves with acute apex | Bolusiella talbotii |
| 5. | Spur at right angle or partly curved under the lip, cylindrical, > 1mm | Bolusiella iridiiolia |
| 5a | Spur in the same plane as the lip, conical, < 1mm long | B. iridiiolia subsp. picea |
| 6. | B. iridiiolia subsp. iridiiolia |
References:
WCSP (2017). 'World Checklist of Selected Plant Families. 24.02-2017; http://apps.kew.org/wcsp/
