Sphaerolaimus, Bastian, 1865

Zograf, Julia K., Pavlyuk, Olga N., Trebukhova, Yulia A. & Tu, Nguyen Dinh, 2020, Description of three new Sphaerolaimus species (Nematoda: Sphaerolaimidae) form the South China Sea, Zootaxa 4755 (3), pp. 491-514 : 508-509

Identification key to valid species of the genus Sphaerolaimus

1 Spicules> 2 anal body diameters........................................................................ 2 - Spicules ≤ 2 anal body diameters........................................................................ 7

2 Spicules longer than tail................................................................................ 3 - Spicules shorter than tail............................................................................... 5 3 Cephalic setae short, 1.3–1.6 µm long .............................................................. S. callisto

- Cephalic setae ≥ 2 µm long............................................................................. 4

4 18–20 supplements present..................................................................... S. cuneatus

- Supplements absent.......................................................................... S. penicillus

5 Gubernaculum with small caudal apophyses.......................................................... S. kleini

- Gubernaculum without apophyses....................................................................... 6

6 Gubernaculum with denticles............................................................ S. macrocirculoides

- Gubernaculum without denticles............................................................. S. macrocirculus

7 Amphid behind the buccal cavity........................................................................ 8

- Amphid at level with the buccal cavity................................................................... 16

8 Gubernaculum absent........................................................................ S. abeskunus

- Gubernaculum present................................................................................. 9

9 Spicules double jointed...................................................................... S. crenellatus

- Spicules not double jointed............................................................................ 10

10 Gubernaculum with dorsal apophyses.................................................................... 11

- Gubernaculum without apophyses...................................................................... 13

11 Spicules with widened distal ends................................................................. S. caspius

- Spicules of even thickness............................................................................. 12

12 Gubernaculum with straight dorsal apophyses....................................................... S. gracilis

- Gubernaculum with L-shaped dorsal apophyses...................................................... S. limosus

13 Tail with numerous hook-shaped setae 25 µm long................................................. S. uncinatus

- Tail with sparse small and thin setae..................................................................... 14

14 Body length> 2 mm, gubernaculum long and narrow.............................................. S. makrolasius

- Body length <2 mm, gubernaculum short, triangular or plate-like............................................. 15

15 Spicules 70 µm or 1.3 corresponding body diameter.............................................. S. occidentalis

- Spicules 15 µm long or 0.8 corresponding body diameter.......................................... S. paragracillis

16 Gubernaculum absent....................................................................... S. maeoticus

- - Gubernaculum present.............................................................................. 17

17 Gubernaculum without apophyses...................................................................... 18

- Gubernaculum with apophyses.......................................................................... 23

18 Gubernaculum shield-shaped.......................................................................... 19

- Gubernaculum different in shape....................................................................... 20

19 Body length <1000 µm ......................................................................... S. minutus

- Body length> 1000 µm ........................................................................ S. hirsutus

20 Gubernaculum stick-shaped..................................................................... S. balticus

- Gubernaculum hook shaped............................................................................ 21

21 Amphid small, ca 17% of corresponding body diameter.............................................. S. peruanus

- Amphid big, ≥ 30% of corresponding body diameter........................................................ 22

22 Amphid ca 30 % of corresponding body diameter.................................................. S. pacificus

- Amphid ≥ 60% of corresponding body diameter.................................................. S. megamphis

23 Anterior sensilla papilliform................................................................... S. papillatus

- Anterior sensilla setiform............................................................................. 24

24 Supplements present................................................................................. 25

- Supplements absent.................................................................................. 27

25 Cervical setae long, 18-20 µm .................................................................... S. rivalis

- Cervical setae short, 8-16 µm ........................................................................... 26

26 Spicules short, 52-63 µm .................................................................. S. micropapillatus

- Spicules long, 83-90 µm ...................................................................... S. valentinae

27 Tail blunt with irregularly shaped end......................................................... S. arcospiculum

- Tail conico-cylindrical................................................................................ 28

28 Gubernaculum with small triangular apophyses............................................................ 29

- Gubernaculum with long well defined apophyses........................................................... 31

29 Spicules ≤ 1 anal body diameter................................................................... S. lutarius

- Spicules> 1.5 anal body diameter....................................................................... 30

30 Gubernaculum with two globose apophyses......................................................... S. ostreae

- Gubernaculum with triangular apophyses......................................................... S. glaphyrus

31 Lateral alae present................................................................................... 32

- Lateral alae absent................................................................................... 33

32 Amphid big,> 40% of corresponding body diameter, spicules short, 1.1 anal body diameters................ S. ganymede

- Amphid small, <30% corresponding body diameter, spicules long, 1.7 anal body diameters....................... S. io

33 Vulva shifted to the posterior half of the body, V = 70-80............................................. S. profundus

- Vulva near the center of the body, V = 55...................................................... S. haurakiensis