Nereis, Linnaeus, 1758

Hsueh, Pan-Wen, 2020, New species of Nereis (Annelida, Polychaeta, Nereididae) from Taiwanese waters, Zootaxa 4802 (1), pp. 1-31 : 29-30

Key to Nereis species reported from East Asia (Adopted partially from Imajima 1972 & Wu et al. 1981)

1. Tentacular cirri distally smooth.......................................................................... 2

- Tentacular cirri distally articulated.......................................................... N. articulata n. sp.

2. Area III with 20+ paragnaths and Area V with at least 1 paragnath.............................................. 3

- Area III without 20+ paragnaths and Area V with or without paragnaths......................................... 5

3. Area V with 1–3 paragnaths, blade of notopodial homogomph falcigers with teeth................................. 4

- Area V with 2–18 paragnaths (depended on body size), blade of notopodial homogomph falcigers with serrations..................................................................................... N. neoneanthes Hartman, 1948

4. Blade of notopodial homogomph falcigers sickle-shaped, base with 2 small teeth on cutting edge....................................................................................... N. guangdongensis Wu, Sun & Yang, 1981

- Blade of notopodial homogomph falcigers rod-like with more than 10 teeth on cutting edge........ N. nuwalianensis n. sp.

5. Area VII & VIII without paragnaths...................................................................... 6

- Area VII & VIII with paragnaths......................................................................... 8

6. Area I with paragnaths, Area II with at least 10 paragnaths.................................................... 7

- Area I without paragnaths, Area II with 0–2 paragnaths........................... N. longior Khlebovich & Wu, 1962

7. Dorsal cirri longer than dorsal ligules, longest tentacular cirri reaching chaetiger 8........... N. surugaense Imajima, 1972

- Dorsal cirri shorter than dorsal ligules, longest tentacular cirri reaching chaetiger 10–12............................................................................. N. surugaense nanhaiensis Shen & Sun in Sun, Wu & Shen, 1978

8. Areas VII & VIII with 1 or 2 transverse rows of paragnaths................................................... 9

- Areas VII & VIII with 3 or more rows or a transverse band of paragnaths....................................... 22

9. Areas I–III without paragnaths.......................................................................... 10

- At least one of Areas I–III with paragnaths................................................................ 12

10. Blade of notopodial homogomph falcigers fusiform with smooth surface.............. N. sinensis Wu, Sun & Yang, 1981

- Blade of notopodial homogomph falcigers not fusiform without smooth surface.................................. 11

11. Blade of notopodial falcigers distally bifid................................................. N. taiwanensis n. sp.

- Blade of notopodial falcigers sickle-shaped with serrations.................... N. huanghaiensis Wu, Sun & Yang, 1981

12. Area III with more than 15 paragnaths................................................................... 13

- Area III with less than 15 paragnaths.................................................................... 16

13. Blade of notopodial falcigers with serrations............................................................... 14

- Blade of notopodial falcigers with teeth........................................... N. denhamensis Augener, 1913

14. Area III with more than 30 paragnaths................................................................... 15

- Area III with less than 20 paragnaths.............................................. N. heteromorpha Horst, 1924

15. Area VI with 7 teeth, notopodial dorsal ligules of posterior chaetiger enlarged................... N. nichollsi Kott, 1951

- Area VI with 10 teeth, notopodial dorsal ligules of posterior chaetiger not enlarged............... N. shitipingensis n. sp.

16. Area VI with 5 or less paragnaths,...................................................................... 17

- Area VI with mostly 10 or more paragnaths................................................ N. taitungensis n. sp.

17. Areas VII & VIII with 10 or more paragnaths............................................................. 18

- Areas VII & VIII with less than 10 paragnaths............................................................. 19

18. Areas VII & VIII with more than 40 paragnaths......................................... N. jacksoni Kinberg, 1866

- Areas VII & VIII with 10–14 paragnaths...................... N. zhongshaensis Shen & Sun in Sun, Wu & Shen, 1978

19. Blade of notopodial falcigers with smooth surface.......................................................... 20

- Blade of notopodial falcigers with tooth.................................................................. 21

20. Areas I & II with paragnaths......................................................... N. coutieri Gravier, 1899

- Areas I & II without paragnaths................................... N. dayana Shen & Sun in Sun, Wu & Shen, 1978

21. Blade of notopodial falciger distally bifid.............................................. N. falcaria ( Willey, 1905)

- Blade of notopodial falciger distally not bifid.......................... N. falcaria multignatha Wu, Sun & Yang, 1981

22. Areas VII & VIII without an isolate row of paragnaths...................................................... 23

- Areas VII & VIII with an isolate row of paragnaths......................................................... 24

23. Areas VII & VIII with 3–4 rows of large paragnaths................................................... N. sp. A

- Areas VII & VIII with 5–6 rows of small paragnaths................................................... N. sp. B

24. Areas VII & VIII with 1 row of large teeth anteriorly and 2 or more rows of small teeth posteriorly................... 25

- Areas VII & VIII with 1 row of large teeth anteriorly and several rows of large teeth interspaced with small teeth posteriorly .................................................................................................. 35

25. Area III with more than 45 paragnaths................................................................... 26

- Area III with less than 45 paragnaths.................................................................... 27

26. Both Areas II & IV with 50 or more paragnaths............................................ N. izukai Okuda, 1939

- Both Areas II & IV with less than 40 paragnaths......................................... N. abyssa Imajima, 2009

27. Areas VII & VIII with 1 row of large teeth and 2-3 rows of small teeth......................................... 28

- Areas VII & VIII with 1 row of large teeth and 4 or more rows of small teeth.................................... 31

28. Notopodial dorsal ligules rounded on anterior chaetigers................................. N. pelagica Linnaeus, 1758

- Notopodial dorsal ligule not rounded on anterior chaetigers.................................................. 29

29. Notopodial dorsal ligules with rectangular elongation on posterior chaetigers, blade of notopodial homogomph falcigers with serrations........................................................................ N. vexillosa Grube, 1851

- Notopodial dorsal ligules without rectangular elongation on posterior chaetigers, blade of notopodial homogomph falcigers with 2–3 teeth...................................................................................... 30

30. Surface of dorsum on anterior chaetigers with narrow horizontal stripes..................... N. zonata Malmgren, 1867

- Surface of dorsum on anterior chaetigers without narrow horizontal stripes..................... N. persica Fauvel, 1911

31. Notopodial dorsal ligules rounded on anterior chaetigers..................................................... 32

- Notopodial dorsal ligules not rounded on anterior chaetigers.................................................. 34

32. Dorsal cirri 2.0–2.3 times as long as dorsal ligules......................................... N. longdongensis n. sp.

- Dorsal cirri 3.0–5.0 times as long as dorsal ligules.......................................................... 33

33. Area V with no paragnaths............................................ N. multignatha Imajima & Hartman, 1964

- Area V with 3–7 paragnaths...................................... N. multignatha paraneanthes Khlebovich, 1996

34. Notopodial dorsal ligules triangular, blunt-tipped, on anterior chaetigers, blade of notopodial homogomph falcigers with serration or smooth.......................................................................... N. paporae n. sp.

- Notopodial dorsal ligules narrow triangular to digitiform on anterior chaetigers, blade of notopodial homogomph falcigers with 2–3 teeth............................................................................ N. wuchiensis n. sp.

35. Notopodial dorsal ligules with rectangular elongation on posterior chaetigers............ N. heterocirrata Treadwell, 1931

- Notopodial dorsal ligules with base enlarged to leaf-like form on posterior chaetigers........... N. grubei (Kinberg, 1866)