Key to the Terebellides species from North East Atlantic and Mediterranean

1 Geniculate acicular chaetae on thoracic CH 6............................................................... 2

- Geniculate acicular chaetae on thoracic CH 5 and CH 6........................................... T. bigeniculatus

2 Thoracic CH 1 to CH 4 ventrally whitish............................................................ T. gracilis

- Thoracic CH 1 to CH 4 of same ventral colouration as following................................................ 3

3 CH 1 notopodia and notochaetae longer than following................................... T. mediterranea spec. nov.

- CH 1 notopodia and notochaetae similar or shorter than following.............................................. 4

4 Branchial lobes moderately fused; a large species (up to 50 mm long).................................... T. stroemii

- Branchial lobes free; a small species (less than 20 mm long)............................................ T. atlantis