Interactive Diagnostic Key to Nematodes

Interactive Diagnostic Key to Plant Parasitic, Freeliving and Predaceous Nematodes

by

UNL Nematology Lab

Adapted from:
An Illustrated Key to Nematodes Found in Fresh Water

Armen C. Tarjan (University of Florida, Lake Alfred)

Robert P. Esser (Florida Department of Agriculture, Gainesville)

Shih L. Chang (Environmental Protection Agency, Cincinnati, Ohio)

Part I

Originally published in J. Water Pollution Cont. Fed. 1977. Vol 49: 2318-2337

Part
II	III	IV

1. Cephalic setae indistinct or absent .

..2

Cephalic setae absent but setae-like head appendages present .

Cephalic setae present .

..69

2. (1) Stylet present .

.3

Stylet absent

..38

3. (2) Base of stylet knobbed or flanged .

.4

Stylet knobs or flanges absent ..

4. (3) Valvate median esophageal bulb present ..

.5

Valvate median esophageal bulb absent

...22

5. (4) Females eel-like .

..........6

Females swollen .

..21

6. (5) Vulva at mid-body .

....7

Vulva on lower third of body .

...14

7. (6) Esophagus not overlapping intestine .

....8

Esophagus overlapping intestine .

....11

8. (7) Stylet length less than 50 microns

.....9

Stylet lenght greater than 80 microns .

..... Dolichodorus

9. (8) Tail terminus bluntly pointed

.....Quinisulcius

Tail terminus not pointed

.....10

10. (9) Tail terminus knobbed

... Psilenchus

Tail terminus never knobbed or pointed .

.. Tylenchorhynchus, Merlinius , Geocenamus (in part), Scutylenchus , Nagelus

11. (7) Labium offset .

...12

Labium flattened amalgamated or nearly so .

.

....13

12. (11) Stylet massive, 40-50 microns long

.. Hoplolaimus

Stylet long and thin, greater than 90 microns long .

.. Belonolaimus

13. (11) Body 0.5-1 mm .

..... Radopholus

Body 2-3 mm long ..... Hirshmaniella

14. (6) Cuticle heavily annulated, stylet elongate .

.15

Cuticle not heavily annulated, stylet short .

....17

Cuticle not heavily annulated, stylet long...

..........Paratylenchus

15. (14) Cuticular sheath absent .

.. 16

Cuticular sheath present

...... Hemicycliophora

16. (15) Annules with cuticular spines or scales ...

..Criconema

Annules plain without spines or scales .

...Mesocriconema

17. (14) Body death position straight ..

.18

Body death position spiral .

..... Helicotylenchus

18. (17) Median esophageal bulb distinct but not pronounced .

...19

Median esophageal bulb well-developed .

... Aphelenchoides

19. (18) Esophagus overlapping intestine .

.....20

Esophagus not overlapping intestine .

..... Tylenchus

20. (19) Median bulb and valves small, stylet usually weak ..

....Ditylenchus

Median bulb valves and stylet well developed, labium flattened .

......Pratylenchus

21. (5) Female body white without eggs .

..... Meloidogyne

Female body brown, usually with eggs .

..... Heterodera

22. (4) Stylet short, less than 100 microns .

.....23

Stylet long, greater than 100 microns ........Xiphinema

23. (22) Stylet complex .

.

..24

Stylet simple .

.....25

24. (23) Stylet with anterior arch-like portion .

... Diphtherophora

Stylet with dorsal thickening piece .

..... Tylencholaimellus

25. (23) Stylet knobs elongate, flange-like .

.....26

Stylet knobs round .

....27

26. (25) Filiform tail .

... Aulolaimoides

Round tail .

..... Enchodelus

27. (25) Tail rounded .

.....28

Tail pointed ..

........Nothotylenchus

28. (27) Basal part esophagus elongate .

.Tylencholaimus

Basal part esophagus oval .............

.......Doryllium

29. (3) Valvate median esophageal bulb absent .

.....30

Valvate median esophageal bulb present

....37

30. (29) Stomal walls not cuticularized .

....31

Stomal walls cuticularized

(Actinolaimus, Metactinolaimus, Neoactinolaimus, Paractinolaimus) .. Actinolaiminae

31. (30) Esophagus with basal expansions

...32

Esophagus expanding uniformly .

.. Oionchus

32. (31) Terminal fifth or sixth of esophagus an ovoid bulb

...33

Posterior third of esophagus swollen .

..36

33. (32) Stylet axial, positioned centrally .

.....34

Stylet not axial orginating from tooth in stoma wall .

...... Campydora

34. (33) Gonads paired, vulva usually near mid-body .

..35

Gonads single, posterior to vulva. Vulva usually anterior to mid-body .

.....Tyleptus

35. (34) Stylet slender .

..Leptonchus

Stylet not slender .

.. Dorylaimoides

36. (32) Stylet axial, positioned centrally

(Dorylaimus, Eudorylaimus, Labronema,Mesodorylaimus, Thornia, Laimydorus, Prodorylaimus) .. Dorylaiminae

Stylet not axial, originating from tooth in stoma wall .

.. Nygolaimus

37. (29) Tail pointed .

.. Seinura

Tail rounded .

......Aphelenchus

38. (2) Teeth present, prominent .

...39

Teeth absent, minute, or indistinct .

.....50

39. (38) Esophagus without mid-region expansion

......40

Esophagus expanded at mid-region .

.....49

40. (39) Tail pointed or tapering .

.....41

Tail rounded..........................

......47

41. (40) Male tail without setae

.....42

Male tail with setae .

..Oncholaimus

42. (41) Stoma with denticles

......43

Stoma without denticles .......

....45

43. (42) Denticles scattered or in longitudinal rows

.....44

Denticles in transverse rows .

... Mylonchulus

44. (43) Denticles situated on longitudinal rib of stoma .

... Prionchulus

Denticles scattered on stoma wall .

..... Sporonchulus

45. (42) Tooth anteriorly directed .

..pic...46

Tooth retrorse .

..... Anatonchus

46. (45) Tooth in basal part of stoma .

......... Iotonchus

Tooth in anterior part of stoma

..... Mononchus

47. (40) Stoma with prominent medial or apical tooth .

.....48

Stoma with small basal tooth

..... Bathyodontus

48. (47) Stoma with 3 teeth, without small basal tooth, caudal glands terminal .

.. Enoplocheilus

Stoma with large anterior & small basal tooth, caudal glands ventral .

.. Mononchulus