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