Key to Synelmis species of Australia and adjacent seas [see Salazar-Vallejo (2003) for a key to worldwide species]

1. Lateral antennae located anteriorly, close to the base of the palps; notospines from chaetiger 5........................ 3

- Lateral antennae located about mid-prostomium; notospines usually after chaetiger 9.............................. 2

2. Antennae and tentacular cirri fusiform, body pigmented................................................. S. rigida

- Antennae and tentacular cirri subulate; body unpigmented......................................... S. sergi sp. nov.

3. Dorsal cirrus on chaetiger 1 longer than following ones................................................. S. gibbsi

- Dorsal cirrus on chaetiger 1 same length as following ones............................................... S. knoxi