Key to species of Sigambra Müller, 1858
(modified after Salazar-Vallejo et al. 2019)
1. Dorsal cirri larger than ventral cirri................................................................................................... 2
– Dorsal and ventral cirri subequal..................................................................................................... 26
2. Chaetiger 2 without ventral cirri........................................................................................................ 3
– Chaetiger 2 with ventral cirri........................................................................................................... 22
3. Pharynx with 8 marginal papillae...................................................................................................... 4
– Pharynx with 13–16 marginal papillae.............................................................................................. 7
4. Dorsal hooks from chaetigers 3–8..................................................................................................... 5
– Dorsal hooks from chaetigers 15–17 (5–18 mm long; up to chaetiger 30?); median and posterior notopodia with 1 capillary; median antenna long, reaching chaetiger 7......... S. vargasi Dean, 1999
5. Median and posterior notopodia with capillaries............................................................................... 6
– Notopodia without capillaries; all neurochaetae with tips entire; median antennae reaching chaetiger 5 (17–23 mm long).................................................... S. papagayu Bamber in Muir & Bamber, 2008
6. Some neurochaetae with bifid tips; median antenna barely longer than laterals, reaching chaetiger 2; median and posterior notopodia with 2 capillaries......... S. bidentata Britayev & Saphronova, 1981
– All neurochaetae with entire tip; median antenna markedly longer than laterals, reaching chaetiger 3; median and posterior notopodia with 1 capillary....... S. qingdaoensis Licher & Westheide, 1997
7. Dorsal hooks from anterior chaetigers (4–18)................................................................................... 8
– Dorsal hooks from median chaetigers (30–40); median antenna twice as long as lateral ones or longer............................................................................................................................................. 21
– Dorsal hooks from posterior chaetigers (42–66), or beyond that (14 mm long); median antenna as long as lateral ones, barely reaching chaetiger 1........................................ S. rugosa Fauchald, 1972
8. Tentacular segment about twice as wide as long............................................................................... 9
– Tentacular segment 4 times as wide as long.....................................................................................11
9. Tentacular segment with anterior margin with rounded projected lobes, external to lateral antennae................................................................................................. Sigambra sp. indet. * (Brazil)
– Tentacular segment with anterior margin smooth, without projected lateral lobes; dorsal hooks from chaetiger 3–4 (14 mm long)............................................................................................................. 10
10. Antennae of similar length; dorsal cirri of median segments 5 times as long as wide.............................................................................................................................................. S. setosa Fauchald, 1972
– Median antenna almost twice as long as lateral ones; dorsal cirri of median segments 3 times as long as wide................................................................................ S. phuketensis Licher & Westheide 1997
11. Tentacular segment with rounded projected lobes in anterior margin; median antenna slightly longer than lateral ones, reaching chaetigers 3–4....................................................................................... 12
– Tentacular segment with anterior margin smooth, without rounded projected lobes...................... 13
12. Dorsal hooks from chaetigers 4–5 (6–12 mm long)........................................... S. parva (Day, 1963)
– Dorsal hooks from chaetiger 8 (2–9 mm long)......................................... S. sundarbanensis sp. nov.
13. Median and posterior notopodia with capillaries............................................................................. 14
– Notopodia without capillaries.......................................................................................................... 20
14. Median antenna short, reaching up to chaetigers 3–4...................................................................... 15
– Median antenna medium-sized, reaching chaetigers 5–7................................................................ 16
– Median antenna long, reaching chaetigers 9–12; dorsal hooks of chaetigers 11–15 (40 mm long); lateral antennae without lateral depressions.............................................. S. bassi sensu Blake, 1994
15. Dorsal hooks from chaetiger 4 (15 mm long); median antenna slightly longer than lateral ones; first dorsal cirri slightly longer than dorsal tentacular ones.................... S. tentaculata sensu Blake, 1994
– Dorsal hooks from chaetiger 12–18 (16 mm long); median antenna twice as long as lateral ones; first dorsal cirri markedly longer than dorsal tentacular ones.... S. elegans Britayev & Saphronova, 1981
16. Median antenna slightly longer than lateral ones, reaching chaetigers 4–6; dorsal hooks from chaetigers 7–10 (5.5 mm long)........................................... S. pettiboneae Hartmann-Schröder, 1979
– Median antenna twice as long as lateral ones.................................................................................. 17
17. Median antenna reaching chaetigers 7–8......................................................................................... 18
– Median antenna reaching up to chaetigers 5–6; dorsal hooks from chaetigers 4–5........................ 19
18. Dorsal hooks from chaetigers 3–9 (5–20 mm long)............................. S. hanaokai (Kitamori, 1960)
– Dorsal hooks from chaetigers 12–18 (24 mm long).................................... S. bassi (Hartman, 1947)
19. All parapodia with ventral cirri shorter than neuropodial lobes; dorsal cirri basally wider......................................................................................................................... S. tentaculata (Treadwell, 1941)
– Median and posterior parapodia with ventral cirri long, reaching tip of neuropodial lobes; dorsal cirri tapered, not wider basally............................................................ S. diazi Salazar-Vallejo et al., 2019
20. Median antenna medium-sized, reaching chaetigers 3–4; posterior region with 4–6 hookless chaetigers; body papillae large in proportion................................................... S. grubii Müller, 1858
– Median antenna short, reaching chaetigers 2–3; posterior region with 2 hookless chaetigers; body papillae small.................................................................... S. hernandezi Salazar-Vallejo et al., 2019
21. Median antenna slightly longer than laterals; body without a constriction on chaetiger 4; dorsal hooks from chaetigers 30–39 (15–24 mm long); posterior chaetigers without capillary notochaetae.................................................................................................... S. olivai Salazar-Vallejo et al., 2019
– Median antenna twice as long as laterals; body with a constriction on chaetiger 4; dorsal hooks from chaetiger 30–40 (16–24 mm long); posterior chaetigers with a single capillary notochaetae.......................................................................................................................... S. constricta (Southern, 1921)
22. Pharynx with 8 marginal papillae.................................................................................................... 23
– Pharynx with 14–16 marginal papillae............................................................................................ 25
23. Median antenna slightly longer than lateral ones............................................................................ 24
– Median antenna twice as long as lateral ones; dorsal hooks from chaetigers 26–28........................................................................................................................... S. ligneroi Salazar-Vallejo et al., 2019
24. Dorsal hooks from chaetiger 4 (0.7 mm wide), tentacular segment as long as wide................................................................................................................................................ S. healyae Gagaev, 2008
– Dorsal hooks from chaetigers 23–30 (45–70 mm long); tentacular segment 4–5 times as wide as long............................................................................................................... S. wassi Pettibone, 1966
25. Dorsal hooks from chaetiger 7, with accessory capillaries; dorsal cirri progressively longer from chaetiger 2............................................................................................... Sigambra sp. Imajima, 2001
– Dorsal hooks from chaetigers 43–70, without capillary chaetae; dorsal cirri of chaetiger 2 smaller than those in following chaetigers............................................................... S. robusta (Ehlers, 1908)
26. Dorsal hooks from chaetiger 6 (1.5 mm long)....................... S. ocellata (Hartmann-Schröder, 1959)
– Dorsal hooks from chaetiger 3 (3.7 mm long).................. S. magnuncus (Paterson & Glover, 2000)
* As per Salazar-Vallejo et al. (2019), this is not completely identified and based upon some specimens which have not been described yet, but are distinct and deserve to be described.