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)
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    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 .. 64 
  • 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 ...29
  • 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 
  • To Part II