Sigambra Müller, 1858

Bhowmik, Moumita, Ghoshal, Priya, Salazar-Vallejo, Sergio I. & Mandal, Sumit, 2021, Sigambra sundarbanensis sp. nov. (Annelida, Pilargidae) from the Indian sector of Sundarbans Estuarine System, with remarks on parapodial glands, European Journal of Taxonomy 744, pp. 49-66 : 60-62

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.