Eusyllis

Brusa, Vivian S., Aguado, M. Teresa, Martín, Guillermo San & Rouse, Greg, 2013, Revision of the genus Eusyllis Malmgren, 1867 (Annelida: Phyllodocida: Syllidae: Eusyllinae), with the description of a new species from the eastern Pacific Ocean, Zootaxa 3599 (1), pp. 37-50 : 41

Key to Eusyllis species

1. Compound chaetae with unidentate falcigers. Body with a distinct colour pattern................................... 2

- Compound chaetae with distinctly bidentate falcigers. Colourless (except for epigamic specimens)..................... 3

2. Two slender transversal bands on each anterior segments. Dorsal simple chaetae similar to bayonet-shaped. Shafts slightly spinulated distally......................................................................... Eusyllis kupfferi

- Single wide transversal band per segment. Dorsal simple chaetae slightly bidentate. Chaetae shafts strongly spinulated distally........................................................................................ Eusyllis maxima

3. Proximal tooth of blades distinctly smaller than distal one, spine-like............................................. 4

- Proximal tooth of blades well developed, similar or bigger than distal one......................................... 5

4. Blades of compound chaetae long and slender (100–54 µm in midbody). Dorsal cirri distinctly longer than body width (about 2–5 times longer than body width). Ventral cirri digitiform..................................... Eusyllis longicirrata

- Blades of compound chaetae shorter (42–32 µm in midbdoy). Dorsal cirri shorter, somewhat longer than body width. Ventral cirri triangular................................................................... Eusyllis grandmariae n. sp.

5. Ventral cirri from first chaetiger broad and laminar, clearly larger than subsequent ones. Aciculae tricuspid..................................................................................................... Eusyllis lamelligera

- Ventral cirri from first chaetiger digitiform, similar to subsequent ones. Aciculae otherwise........................... 6

6. Compound chaetae with similar blades, short and bidentate, with proximal tooth slightly longer than distal one..................................................................................................... E. blomstrandi

- Compound chaetae with falcigers of different sizes, some elongated, others similar in size............................ 7

7. Aciculae of medium and posterior parapodia thick, distally curved, protruding out from parapodial lobes. Denticled arc with about 24 (or more) small teeth. Falcigers with proximal tooth distinctly larger than distal one............ Eusyllis assimilis

- Aciculae all slender, straight, not protruding out from parapodial lobes. Denticled arc with about 15 big teeth. Teeth of com- pound chaetae similar in size.............................................................. Eusyllis nuchalata