Opisthosyllis, Langerhans, 1879

Martín, Guillermo San, Hutchings, Pat & Aguado, María Teresa, 2008, Syllinae (Polychaeta, Syllidae) from Australia. Part. 2. Genera Inermosyllis, Megasyllis n. gen., Opisthosyllis, and Trypanosyllis, Zootaxa 1840, pp. 1-53 : 22-23

Key to Australian species of Opisthosyllis

1. Dorsum with numerous papillae ( Figs 28A, B) .......................................................... Opisthosyllis viridis

- Dorsum without papillae..............................................................................................................................2

2. Mid-posterior and posterior parapodia with thick, simple chaetae formed by enlarged shafts, blades absent.....................................................................................................................................................................3

- Without thick, simple chaetae..................................................................................................................... 4

3. Dorsal cirri slender, elongated ( Fig. 18A), some longer than body width ............... Opisthosyllis japonica

- Dorsal cirri relatively thick, shorter than body width ( Fig. 24A) ......................... Opisthosyllis simpliseta

4. Dorsal cirri long, several times longer than body width ( Fig. 21). Compound chaetae all bidentate ......... ............................................................................................................................ Opisthosyllis longicirrata

- Dorsal cirri similar in length to body width or slightly shorter ( Fig. 16A). Midbody to Posterior compound chaetae unidentate .................................................................................................... Opisthosyllis brunnea