individuals

Hodda, Mike, 2022, Phylum Nematoda: feeding habits for all valid genera using a new, universal scheme encompassing the entire phylum, with descriptions of morphological characteristics of the stoma, a key, and discussion of the evidence for trophic relationships, Zootaxa 5114 (1), pp. 318-451 : 341-344

Key to morphology of individuals of different trophic groups

Number in parentheses beside couplet number refers to the couplet preceding it in the key.

1 Nematode located on or within vertebrate body or gut........................................ Parasite-Vertebrate

Nematode not located on or within vertebrate body or gut..................................................... 2

2(1) Nematode located on or within arthropod.................................................................. 3

Nematode not associated with arthropod................................................................... 6

3(2) Stylet present........................................................................................ 4

Stylet absent......................................................................................... 5

4(3) 1 to 3 large nematodes only, haemolymph clear...... Parasite-Invertebrate-Arthropod ( Mermithidae or Sphaerulariidae )

Many small nematodes, haemolymph clear or cloudy.... Parasite-Invertebrate-Arthropod ( Aphelenchidae or Tylenchidae )

5(3) Host haemolymph cloudy......................... Parasite-Invertebrate-Arthropod ( Heterorhabditis or Steinernema ).................................................................. Microbial Feeder-Processor-Particulate

Host haemolymph clear............ Parasite-Invertebrate-Arthropod (genus other than Heterorhabditis or Steinernema ).................................................................... Parasite-Vertebrate (intermediate host)

6(2) Nematode located on or within invertebrate other than arthropod......................... Parasite-Invertebrate-Other

Nematode not located on invertebrate..................................................................... 7

7(6) Nematode located on or within plant or plant part............................................................ 8

Nematode not located on or within plant or plant part........................................................ 31

8(7) Nematode located on or within aerial part of plant (stem, leaves or seeds)......................................... 9

Nematode located on or within below-ground part of plants (roots, stolons, corms, tubers or bulbs)................... 19

9(8) Nematode located within plant seeds..................................... Parasite-Plant-Aerial-Internal modifier

Nematode not located within plant seeds.................................................................. 10

10(9) Nematode located in flower or fruit bud.................................. Parasite-Plant-Aerial-Internal modifier

Nematode not located in flower or fruit bud............................................................... 11

11(10) Nematode located within leaves or stem.................................................................. 12

Nematode not located within leaves or stem........................................ Parasite-Plant-Wood or bark

12(11) Nematode located on or within plant leaves................................................................ 13

Nematode located on or within plant stem................................................................. 15

13(12) Nematode located on surface of leaf............................... Parasite-Invertebrate-Arthropod ( Mermithidae )

Nematode within leaf................................................................................. 14

14(13) Leaf not galled, may be distorted............. Parasite-Plant-Aerial-Internal migrator ( Aphelenchoides or Ditylenchus )

Leaf galled............................... Parasite-Plant-Aerial-Internal modifier ( Fergusobia and related genera)........................................................................ Parasite-Invertebrate-Arthropod

15(11) Plant live........................................................................................... 16

Plant dead................................................................... Parasite-Plant-Wood or bark

16(15) Nematode within plant stem............................................................................ 17

Nematode on surface of plant stem...................................................................... 18

17(16) Stem not woody (herbaceous).......................................... Parasite-Plant-Internal migrator-Aerial

Stem woody.................................................. Parasite-Plant-Wood or bark ( Bursaphelenchus )

18(16) Stem surface smooth.................................................. Parasite-Plant-Internal migrator-Aerial

Stem surface with fibrous bark................................................... Parasite-Plant-Wood or bark

19(8) Stylet.............................................................................................. 20

No stylet (may be associated with decaying plant material or microbial decomposers).............................. 30

20(19) All or a substantial portion of nematode body within root..................................................... 21

Most of nematode body on surface of root................................................................. 27

21(20) Root modified to swelling....................................... Parasite-Plant-Internal modifier-Below ground

Root not swelled..................................................................................... 22

22(21) Nematode body swollen................................................................................................................. Parasite-Plant-Internal modifier-Below ground (parasitic juvenile or adult female)

Nematode body not swollen............................................................................ 23

23(22) Nematode adult female with vulva and/or eggs....................... Parasite-Plant-Internal migrator-Below ground

Nematode not adult female, no vulva or eggs.............................................................. 24

24(23) Stylet thick, with large terminal knobs.............................. Parasite-Plant-Internal migrator-Below ground

Stylet slender, with small terminal knobs.................................................................. 25

25(24) Juvenile nematode............................................. Parasite-Plant-Internal modifier-Below ground

Adult male nematode................................................................................. 26

26(25) Stylet and oesophagus not vestigial................................ Parasite-Plant-Internal modifier-Below ground

Stylet and oesophagus vestigial................................... Parasite-Plant-Internal modifier-Below ground............................................................Parasite-Plant-Internal migrator-Below ground

27(19) Stylet length <20µm long, with terminal knobs <5µm across................................................. 28

Stylet length> 20µm long, with terminal knobs>5µm across................................................. 29

28(27) Stylet thick, robust,>10µm or 1 head diameter long, knobs medium (3 to 5 µm across).............................................................................................. Parasite-Plant-External root feeder-Surface

Stylet thin, delicate, <15µm or 1.5 head diameters long, knobs small (<4µm across), stylet delicate............................................................................................. Parasite-Plant-External browser

29(27) Stylet anterior portion solid, evenly curved, posterior portion with small terminal flange............................................................................................. Parasite-Plant-External root feeder-Surface

Stylet anterior portion hollow, straight or curved unevenly, posterior portion with no terminal flange, large flanges or knobs............................................................. Parasite-Plant-External root feeder-Sub-surface

30(19) Mouth cavity with teeth or denticles, 1 or 2 plates in each wall................. Microbial feeder-processor-particulate

Mouth cavity without teeth, but with multiple plates in the walls............................ Microbial feeder-crusher

31(7) Mouth present or absent, mouth cavity absent, oesophagus not muscular, modified to food storage cells, intestine disconnected from oesophagus, anus absent........................................................ Parasite-Host Unknown ........................................................................ Parasite-Invertebrate-Arthropod ............................................................................ Parasite-Invertebrate-Other

Mouth present, cavity present or absent, oesophagus at least partially muscular, not modified to food storage cells, intestine connected to oesophagus, anus present................................................................... 32

32(31) Stylet present....................................................................................... 33

Stylet absent........................................................................................ 62

33(32) Stylet without terminal flanges or knobs.................................................................. 34

Stylet with terminal expansion in the form of a flange or flanges, or knobs....................................... 42

34(33) Stylet broad, diameter>30% length, aperture>30% length, body large (>1000µm long)................ Predator-Piercer

Stylet narrower, diameter <30% length, aperture <30% length................................................ 35

35(34) Lips curled forward...................................................................... Predator-Piercer

Lips not curled...................................................................................... 36

36(35) Cephalic framework large and consisting of heavily cuticularized pieces............................. Predator-Piercer

Cephalic framework absent or small and lightly cuticularized................................................. 37

37(36) Stylet long (more than 40µm long), narrow (diameter <10% length)............................................ 38

Stylet short, aspect ratio wider.......................................................................... 39

38(37) Anterior stylet solid.................................... Parasite-Plant-External root feeder-Surface (Trichoridae)

Anterior stylet hollow............................ Parasite-Plant-External root feeder-Sub-surface ( Xiphinematidae )

39(37) Oesophageal bulb posterior to nerve ring.................................................................. 40

Oesophageal bulb anterior to nerve ring.................................................................. 41

40(39) Terminal oesophageal bulb short (length <2x body diameter)............ Parasite-Plant-External browser ( Leptonchidae )

Terminal oesophageal bulb long (length>2x body diameter).............. Microbial feeder-Piercer (Other Dorylaimida )

41(39) Stylet lumen broad............................................................ Predator-Piercer ( Seinuridae )

Stylet lumen narrow, short....................................... Parasite-Plant-External browser ( Aphelenchida )............................................................................... Microbial Feeder-Piercer

42(33) Body swollen.................................... Parasite-Plant-Internal modifier-Below ground ( Heteroderidae )

Body vermiform..................................................................................... 43

43(42) Stylet>25µm long................................................................................... 44

Stylet <25µm long................................................................................... 45

44(43) Anterior stylet solid.................................... Parasite-Plant-External root feeder-Surface (Trichoridae)

Anterior stylet hollow.................. Parasite-Plant-External root feeder-Sub-surface ( Xiphinematidae , Tylenchida )

45(43) Stylet>20µm long................................................................................... 46

Stylet <20µm long................................................................................... 50

46(45) Head low..................................................... Parasite-Plant-Internal modifier-Below ground

Head high................................................... Parasite-Plant-External root feeder-Sub-surface

47(45) Nerve ring posterior to oesophageal bulb............................................... Microbial feeder-Piercer ........................................................................ Parasite-Plant-External browser

Nerve ring anterior to oesophageal bulb.................................................................. 48

48(47) Median oesophageal bulb absent..................................................... Microbial feeder-Piercer ........................................................................ Parasite-Plant-External browser

Median oesophageal bulb present....................................................................... 49

49(48) Cephalic framework strong, terminal knobs large (>5µm across)......... Parasite-Plant-Internal migrator-Below ground

Cephalic framework weak or absent, terminal knobs small (<5µm across).................................................................................................... Parasite-Plant-External root feeder-Sub-surface

50(45) Stylet <10µm long......................................................... Parasite-Plant-External browser

Stylet>10µm long................................................................................... 51

51(50) Juvenile............................................................................................ 52

Adult male......................................................................................... 54

Adult female........................................................................................ 62

52(51) Tail with long hyaline tip, rounded tip.............................. Parasite-Plant-Internal modifier-Below ground

Hyaline tail tip short or absent, shape variable.............................................................. 53

53(52) Tail long, filiform.......................................................... Parasite-Plant-External browser

Tail shorter, not filiform............................................ Parasite-Plant-External root feeder-Surface ........................................................................ Parasite-Plant-External browser ............................................................................... Microbial feeder-Piercer

54(51) Stylet vestigial, oesophagus poorly defined, thin............................................................ 55

Stylet not vestigial, oesophagus with defined structure, thick in places.......................................... 58

55(54) Spicules terminal, tail rounded.................................... Parasite-Plant-Internal modifier-Below ground

Spicules not terminal, tail conoid........................................................................ 56

56(55) Body thick (length <20 times maximum diameter)................... Parasite-Plant-External root feeder-Sub-surface

Body normal shape (>20 times maximum diameter)......................................................... 57

57(56) Head bulbous, with distinct constriction, high........................ Parasite-Plant-Internal migrator-Below ground

Head not bulbous (tapering, without distinct constriction (not distinctly offset) high or low....................................................................................... Parasite-Plant-External root feeder-Sub-surface

58(54) Stylet knobs large (>5µm across), strong cephalic framework............................................................................................................... Parasite-Plant-Internal migrator-Below ground

Stylet knobs small (<5µm across), light cephalic framework.................................................. 59

59(58) Tail very long, filiform...................................................... Parasite-Plant-External browser ............................................................... Parasite-Plant-External root feeder-Surface

Tail shorter, not filiform............................................................................... 60

60(59) Tail short, spicules very near end.................................. Parasite-Plant-Internal modifier-Below ground

Tail longer, spicules at side............................................................................. 61

61(60) Nerve ring around intestine, oesophageal bulb occupies>60% of body diameter............... Microbial feeder-Piercer .................................................................. Parasite-Plant-Internal migrator-Aerial ........................................................................ Parasite-Plant-External browser

Nerve ring around oesophagus.......................................................................... 62

62(61) Muscular oesophageal bulb length>2.5 times diameter................................... Microbial feeder-Piercer ............................................................... Parasite-Plant-External root feeder-Surface ........................................................................ Parasite-Plant-External browser

Muscular oesophageal bulb length <2.5 times diameter................................... Microbial feeder-Piercer ............................................................ Parasite-Plant-Internal modifier-Below ground .................................................................. Parasite-Plant-Internal migrator-Aerial ............................................................ Parasite-Plant-Internal migrator-Below ground ............................................................... Parasite-Plant-External root feeder-Surface ........................................................................ Parasite-Plant-External browser

63(51) One oesophageal bulb................................................................................. 64

Two oesophageal bulbs or swellings..................................................................... 65

64(63) Nerve ring posterior to oesophagus, oesophageal bulb occupies most of body diameter....................................................................................................... Parasite-Plant-External browser ............................................................................... Microbial feeder-Piercer

Nerve ring anterior to intestine, stylet moderate or short............................ Parasite-Plant-External browser

65(63) Stylet knobs large (>5µm across), strong cephalic framework........... Parasite-Plant-Internal migrator-Below ground

Stylet knobs small (<5µm across), light cephalic framework.................................................. 66

66(65) Tail very long, filiform...................................................... Parasite-Plant-External browser

Tail shorter, not filiform............................................ Parasite-Plant-External root feeder-surface ........................................................................ Parasite-Plant-External browser ............................................................................... Microbial feeder-Piercer

67(31) Mouth cavity tiny or absent, oesophagus not muscular, not connected to gut and modified as food storage cells.............................................................................................. Parasite-Invertebrate

Mouth cavity connected to oesophagus and intestine........................................................ 68

68(67) Mouth cavity blocked or filled........................................... Microbial feeder-Processor-Particulate .................................................................................. Parasite-Invertebrate

Mouth cavity not blocked or filled....................................................................... 69

69(68) Mouth narrow (<20% head diameter).................................................................... 70

Mouth broad (>20% head diameter)...................................................................... 73

70(69) Stoma with no teeth (within mouth cavity or not)........................................................... 71

Stoma with teeth (within mouth cavity or not)............................... Microbial feeder-Processor-suspension

71(70) Mouth with more than 2 separate thickened plates in wall................................ Microbial feeder-Crusher

Mouth with 2 or less thickened plates in wall.............................................................. 72

72(71) Mouth with longitudinal ridges around opening (cheilorhabdions elaborated into longitudinal ridges)....................................................................................... Microbial feeder-Processor-suspension

Mouth without longitudinal ridges around opening ridges simple (cheilorhabdions not elaborated)........................................................................................... Microbial feeder-Sucker-suspension

73(69) Stoma with no teeth (within mouth cavity or not)........................................................... 74

Stoma with teeth (within mouth cavity or not).............................................................. 77

74(73) Mouth with more than 2 separate thickened plates in wall................................ Microbial feeder-Crusher

Mouth with 2 or less thickened plates in wall.............................................................. 75

75(74) Mouth with longitudinal ridges around opening (cheilorhabdions elaborated into longitudinal ridges), mouth cavity <50% diameter deep........................................................ Microbial feeder-Processor-suspension

Mouth without longitudinal ridges around opening ridges simple (cheilorhabdions not elaborated), mouth cavity>50% diameter deep............................................................................................... 76

76(75) Mouth containing denticles............................................. Microbial feeder-Processor-Particulate

Mouth not containing denticles............................................ Microbial feeder-Sucker-Particulate

77(73) Tooth near entrance to mouth....................................................... Microbial feeder-Scraper

Tooth not near entrance to mouth........................................................................ 78

78(77) Body small to medium size, mouth with mostly thin cuticular lining, diameter <50% of head diameter...................................................................................... Microbial feeder-Processor-Particulate

Body medium to large size, mouth with mostly greatly thickened cuticle, diameter>50% of head diameter Predator-Chewer

Note that many nematodes fall into more than one trophic group, and that the different types of parasites of plants are almost indistinguishable in some cases.