Key to Families (and Subfamilies) of Plant and Soil Nematodes

Rev. 07/04/24

1	a	Nematodes with a protrusible stylet (stomatostyle) or spear (odontostyle)	go to 2
1	b	Nematodes without protrusible stylet or spear	go to 24
2	a	Stylet and three-part esophagus with median bulb (metacorpus), males with or without bursa	go to 3
2	b	Spear and two-part esophagus with posterior swollen (postcorpus), males usually without bursa but with supplements	go to 16
3	a	Median bulb large with refractive valve, flattened against body wall, stylet knobs absent or small	go to 4
3	b	Median bulb not refractive, stylet knobs obvious	g o to 5
4	a	Stylet without knobs, tail rounded, male with bursa	Aphelenchidae
4	b	Stylet with small knobs, tail pointed, male usually without bursa	Aphelenchoididae	Key to some Genera
5	a	Esophageal glands overlap intestine	g o to 6
5	b	Esophageal glands enclosed in bulb that abuts intestine	go to 11
6	a	Cephalic framework well-developed, lip-region high; females with two gonads	go to 7
6	b	Posterior gonad reduced to a post-uterine sac, vulva at 70-90%, lip-region flattened or cephalic framework absent	go to 10
7	a	Tail tip, anus and vulva in close proximity on posterior of swollen female, male body twisted, male without bursa	go to 8
7	b	Anus and vulva anterior to tail tip even when female swollen, male body not twisted, male with bursa	go to 9
8	a	Juvenile and female stages are sedentary endoparasites, female greatly swollen; male without bursa, body twisted, migratory in soil Body of dead female forms cyst and retains some or all eggs – subfam. Heteroderinae	Heteroderidae	Key to some Genera
	b	Juvenile and female stages are sedentary endoparasites, female greatly swollen; male without bursa, body twisted, migratory in soil Female body does not form cyst, eggs deposited in matrix – subfam. Meloidogynidae	Meloidogynidae
	c	Adult females sedentary endoparasites, greatly swollen; pre-adults vermiform; male without bursa, body twisted, migratory in soil Female body does not form cyst, eggs deposited in matrix – subfam. Nacobboderinae	Heteroderidae
9	a	Stylet 2-3 x stylet body diameter, tail < 2 x anal body diameter, body spiral when heat-killed, vulva around 60% Mature female remains vermiform – subfam. Hoplolaiminae	Hoplolaimidae	Key to some Genera
	b	Stylet 2-3 x stylet body diameter, tail < 2 x anal body diameter, body spiral when heat-killed, vulva around 60% Mature female saccate sedentary semi-endoparasite – subfam. Rotylenchulinae	Hoplolaimidae	Key to some Genera
	c	Tail > 2.5 x anal body diameter, phasmids on tail region Long nematodes, stylet > 3 x stylet body diameter – subfam. Belonolaiminae	Dolichodoridae	Key to some Genera
	d	Tail > 2.5 x anal body diameter, phasmids on tail region Stylet < 1.5 x stylet body diameter – subfam. Telotylenchinae	Dolichodoridae	Key to some Genera
10	a	Lip-region flattened but cephalic framework well-developed Female remains vermiform – subfam. Pratylenchinae	Pratylenchidae	Key to some Genera
	b	Lip-region flattened but cephalic framework well-developed Female a saccate endoparasite – subfam. Nacobbinae	Pratylenchidae	Key to some Genera
	c	Cephalic-framework weak or absent	Anguinidae	Key to some Genera
11	a	Females with two gonads, males with caudal bursa	Dolichodoridae	Key to some Genera
11	b	Posterior female gonad reduced to a post-uterine sac, males with adanal bursa (if present)	go to 12
12	a	Stylet short (< stylet body diameter), tail pointed to filiform	go to 13
12	b	Stylet long so that knobs are close to median bulb valve, procorpus swollen and fused with metacorpus	go to 14
13	a	Tail long and filiform (>5 x anal body diameter)	Tylenchidae	Key to some Genera
13	b	Tail pointed (<5 x anal body diameter), cephalic framework absent	Anguinidae	Key to some Genera
14	a	Thick cuticle with coarse striations	go to 15
	b	Female swollen, excretory pore posterior on body, female a saccate sedentary semi-endoparasite – subfam. Tylenchulinae	Tylenchulidae	Key to some Genera
	c	Cuticle with fine striations, male often without stylet, body C-shaped – subfam. Paratylenchinae	Tylenchulidae	Key to some Genera
15	a	Large body diameter, sausage shape, slow moving, anchor-shaped stylet knobs – subfam. Criconematinae	Criconematidae	Key to some Genera
15	b	Extra cuticular sheath, pointed tail, rounded stylet knobs – subfam. Hemicycliophorinae	Criconematidae	Key to some Genera
16	a	Spear with complex configuration, loose-fitting cuticle	Diphtherophoridae
16	b	Spear simple, cuticle not loose but may be swollen	go to 17
17	a	Spear dorsally curved, anus almost terminal	Trichodoridae	Key to some Genera
17	b	Spear straight, anus not terminal - tail present	go to 18
18	a	Long, slender nematodes (1-12 mm), spear > 50 µm, long spear extension (odontophore)	Longidoridae	Key to some Genera
18	b	Short spear	g o to 19
19	a	Postcorpus of esophagus with muscular sheath	Belondiridae	Key to genera of Belondiridae
19	b	No muscular sheath around esophagus	go to 20
20	a	Spear extension (odontophore) thick and curved	Leptonchidae	Key to genera of Leptonchidae
20	b	Spear extension not curved	go to 21
21	a	Plump nematodes, tail rounded, with or without point	go to 22
21	b	Slender nematodes, tail conoid to filiform	go to 23
22	a	Spear slightly curved, small opening	Nordiidae	Key to genera of Nordiidae
22	b	Spear with large opening, cuticle appears layered at tail	Aporcelaimidae	Key to genera of Aporcelaimidae
23	a	Large nematodes (>2 mm), tail filiform (may be rounded in male)	Thornenematidae
23	b	Medium size (1-2 mm), tail conoid, body generally curved	Qudsianematidae	Key to genera of Qudsianematidae
24	a	Body asymmetrical, caterpillar-like	Bunonematidae
24	b	Body symmetrical	go to 25
25	a	Median bulb present, tail filiform	Diplogastridae
25	b	Median bulb absent	go to 26
26	a	Esophagus with terminal bulb or swelling	go to 27
26	b	Esophagus cylindrical, no swellings	go to 37
27	a	Terminal bulb without valves	go to 28
27	b	Terminal bulb with valves	go to 29
28	a	Cuticle not striated	Monhysteridae
28	b	Cuticle clearly striated	Bastianiidae
29	a	Aquatic forms; cuticle striated and punctated	Chromadoridae
29	b	Cuticle without punctations	go to 30
30	a	Stoma cavity with teeth, tail filiform	Diplogastridae
30	b	Stoma cavity without teeth	go to 31
31	a	Head with labial extensions or crown	go to 32
31	b	Head without extensions	go to 34
32	a	Head with lateral cuticular extensions	Plectidae
32	b	Head with anterior extensions only	go to 33
33	a	Labial extensions crown-shaped	Teratocephalidae
33	b	Labial-extensions thorn- or antler-shaped	Cephalobidae
34	a	Tail tip with spinneret, amphids easily visible, males with tubular supplements	Plectidae
34	b	Tail tip without spinneret	go to 35
35	a	Stoma cavity cylindrical, cuticular walls, males with bursa	Rhabditidae
35	b	Stoma cavity funnel-shaped, walls not cuticular, posterior female gonad reduced, anterior gonad reflexed and extending beyond vulva	go to 36
36	a	Stoma cavity clearly present, anteriorly cylindrical	Panagrolaimidae
36	b	Stoma cavity difficult to see, only anterior section open	Cephalobidae
37	a	Cuticle striated	Bastianiidae
37	b	Cuticle smooth	go to 38
38	a	Slender nematodes, no obvious stoma cavity or setae	Alaimidae
38	b	Clear stoma cavity or setae	go to 39
39	a	Amphids round, clearly visible	Monhysteridae
39	b	Amphids difficult to see, not round	go to 40
40	a	Stoma cavity large, walls cuticular walls	go to 41
40	b	Stoma cavity funnel-shaped or closed anteriorly, walls not cuticular	go to 42
41	a	Tail filiform, setae present	Prismatolaimidae
41	b	Tail not filiform, large stoma cavity with teeth	Mononchidae
42	a	Funnel-shaped stoma with small teeth	Tobrilidae
42	b	Stoma closed anteriorly, one tooth and two tiny denticles in lumen	Tripylidae

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February 2011

Howard Ferris Key modified from: Tom Bongers

Department of Nematology Wageningen University

University of California Wageningen

Davis, CA 95616 The Netherlands