Sphaerosyllis,

Martín, Guillermo San, 2017, Taxonomic contribution to the genus Sphaerosyllis (Annelida: Syllidae: Exogoninae) in the Black Sea, Zootaxa 4329 (3), pp. 281-291: 288-289

Key to species of the genus Sphaerosyllis  Edit from the Black Sea

1. Parapodial glands present...............................................................................2

- Parapodial glands absent................................................................................5

2. Dorsal cirri shorter than parapodial lobes, at least in anterior chaetigers.......................................... 3

- Dorsal cirri longer than parapodial lobes...................................................................4

3. Blades of falcigers strongly serrated, short (<9 µm); shafts with strong distal spines..................................

.................................................................. Sphaerosyllis thomasi San Martín, 1984b  Edit - Blades of falcigers moderately serrated only in anterior and midbody dorsalmost chaetae; blades with slight dorso-ventral gradation but always longer than 9 µm; shafts smooth................................... Sphaerosyllis pontica  Edit sp. nov. 4. Blades of falcigers without marked dorso-ventral gradation in length................. Sphaerosyllis taylori Perkins, 1981  Edit

- Blades of falcigers with a marked dorso-ventral gradation in length (dorsalmost falcigers at least 1.5 times the length of ventral ones)................................................................ Sphaerosyllis hystrix Claparède, 1863  Edit

5. All parapodia with one straight acicula with subdistal enlargement; midbody parapodia with one enlarged modified chaetae lacking the blade....................................................... Sphaerosyllis bulbosa  Edit Southern, 1914  Edit

- Anterior parapodia with two aciculae each, one straight and one with tip bent at right angle; midbody parapodia with all heterogomph chaetae having blades........................................... Sphaerosyllis pirifera Claparède, 1868  Edit