SUBORDER
RHABDITINA
Khuong B. Nguyen
Entomology & Nematology
Department
University of Florida
The illustrations in this document (collected from different
sources mentioned in the
text), the key and diagnoses were prepared for students in the course Nematode
Taxonomy and Systematics. Other users are welcome.
Key to Superfamilies:
1- Stoma short, with weakly
cuticularized rhabdions; bursa absent
(Fig.1,2)
.......................................................... Aloionematoidea .....
3
Stoma cylindrical, well
cuticularized; bursa present supported by ribs,
sometimes reduced
........................................................................................................2
2 (1)- Body asymetrical, left side with
longitudinal ridges, right side with various structures
such as network pattern, tubercles, warts, fins (Fig. 4).... Bunonematoidea ............4
Body symetrical; various structures such as network pattern, tubercles, warts,
fins absent
................................................................................Rhabditoidea .......11
One family
....................................................................................Alloionematidae
3 (1)- Labial region with 6 fused lips;
dorsal metarhabdion with numerous denticles
(Fig. 1)...............................................................................................Alloionema
Labial region with 4 lips; metastom without denticles; esophagus with a slight
swelling
anterior to median bulb (Fig. 2)
....................................................Rhabditophanes
4 (2)- Right side of body with
hexagonal network, tubercles or warts, left side with 5
longitudinal ridges (Fig.
4-10 )..............................................Bunonematidae.......5
Right side of body without network, tubercles or warts but with rows of
rhomboidal
structures, left side with longitudinal ridges (Fig. 3) ............... Pterygonematidae
Only one subfamily
................................................................ Pterygonematinae
Only one genus (Fig. 3) ................................................................Pterygorhabditis
5 (4)- Right side of body with warts,
papillae or longitudinal ridges (Fig. 4-7)
...............................................................................................Bunonematinae.. ..6
Right side with large shield-like structures or with crust-like swellings
(Fig.
8-10)....................................................................... Craspedonematinae....9
6 (5)- Dorsal and ventral menbranes
forming collar on right side of body; warts paired,
supported by internal rods (Fig. 4)
......................................................Bunonema
No collar forming on right side of body; warts without internal rods, paired,
unpaired
or lacking (Fig.
5)..................................................................................................7
7 (6)- Warts or papillae absent, right
side with striated ridges (Fig. 5) ...........Rhodonema
Warts or papillae present, striated ridges on right side absent
(Fig.
6,7)..............................................................................................................8
8 (7)- Right side of body ornamented
with single row of rod-like warts
(Fig. 6)
...............................................................................................Serronema
Two or more warts joined to form paired or unpaired fins, or continuous rows
(Fig. 7)...........................................................................................Rhodolaimus
9 (5)- Right side without warts but
with several shields or crust-like swellings
(Fig. 8)
.......................................................................................Craspedonema
Right side with warts and shields (Fig. 9,
10).......................................................10
10 (9)- Warts paired, in two
longitudinal rows (Fig. 9) ...............................Aspidonema
Warts unpaired, in single row alternating with large shields or crust-like
structures
(Fig. 10)..........................................................................................
Sachsium
Steinernematidae & Heterorhabditidae
11 (2)- Dorsal and ventral lips
transformed into cuticularized fossors
(Fig. 11)
..............................................................................Diploscapteridae
Only one subfamily
.............................................................. Diploscapterinae
Only one genus (Fig. 11) ..............................................................Diploscapter
Dorsal and ventral lips normal
..........................................................................12
12 (11)- Stoma long with large,
transverse dorsal tooth
(Fig. 12, 13)...........................................................Odontorhabditidae... ....14
Stoma long with parallel walls, without tooth (Fig. 14,
15)...............................13
13 (12)- Stoma about twice as long as
wide; esophageal corpus cylindrical; bursa
absent.................................................................Rhabditonematidae..........15
Stoma more than 3 times as long as wide (except in Amphidirhabditinae, then
amphids large); bursa generally well developed, if rudimentary, then esophageal
corpus distinctly swollen............................................Rhabditidae.................16
14 (12)- Cheilorhabdion strongly
cuticularized, female tail long, tapering gradually
(Fig. 12)............................................................................Diploscapteroides
Cheilorhabdion slightly cuticularized, female tail narrowing suddenly to form
spike
(Fig. 13)
.......
........................................................................Cephaloboides
15 (13)- Metarhabdion with small
denticles, female tail long, about 1/8 of body length
(Fig. 14).................................................................................Rhabditonema
Metarhabdion without denticles; female tail short, about 1/50 of body length
(Fig. 15)................................................................................Saprorhabditis
16 (13)- Anterior end of intestinal
wall folded (Fig. 16); bursa absent
................................................................................Stomachorhabditinae
Only one genus (Fig. 16) ....................................................Stomachorhabditis
Anterior end of intestinal wall not folded, bursa present
..................................17
17 (16)- Stoma short, amphids large, at
about mid-stoma; cheilorhabdion long, curved,
well cuticularized (Fig.17) ..........................................Amphidirhabditinae
Only one genus (Fig. 17) .....................................................Amphidirhabditis
Stoma longer, amphids very small, on lateral lips; cheilorhabdion simple, not
well
cuticularized.............................................................................................18
18 (17)- Stoma usually long and narrow;
glotoid apparatus and denticles absent
..............................................................................Protorhabditinae.............22
Stoma typical rhabditoid; glotoid apparatus and denticles present ....................19
19 (18)- Female usually small, gonad
single; vulva close to anus
.............................................................................Mesorhabditinae.............25
Female gonads usually paired, vulva at
mid-body.............................................20
20 (19)- Bursa peloderan
......................................................Peloderinae ..................32
Bursa leptoderan
............................................................................................21
21 (20)- Lips with numerous cilliae,
anterior part of esophagus covering more than
half of stoma (Fig. 38-39) .....................................Ablechroiulinae ..............39
Lips without cilliae, anterior part of esophagus usually covering less than
half of stoma ............................................................Rhabditinae ................40
Subfamily Protorhabditinae:
22 (18)- Female gonad single; spicules
fused (Fig. 18) ......................Parasitorhabditis
Female gonads paired; spicules not
fused........................................................23
23 (22)- Bursa pseudopeloderan; corpus
of esophagus
cylindrical, isthmus very weak (Fig. 19)
..............................Paradoxorhabditis
Bursa peloderan; esophagus with distinct corpus and
isthmus...........................24
24 (23)- Anterior end of prorhabdion
with three small teeth; bursa closed
(Fig. 20)..........................................................................
Prodontorhabditis
Prorhabdion without small teeth; bursa usually open
(Fig. 21)..................................................................
...............Protorhabditis
Subfamily Mesorhabditinae:
25 (19)- Cheilorhabdion cuticularized
(Fig. 22-24).......................................................26
Cheilorhabdion not cuticularized
....................................................................28
26 (25)- Labial edges strongly
cuticularized (Fig. 22).......................... Teratorhabditis
Labial edges not strongly cuticularized ...................
.......................................27
27 (26)- Bursa pseudopeloderan
(Fig. 23) ..................................................Rhabpanus
Bursa peloderan (Fig. 24) ...............................................................Cruznema
28 (25)- Female tail very short,
broadly rounded or narrowing suddenly with spine at
terminus (Fig. 25,26) ................................
...................................................29
Female tail elongate, conical with pointed terminus
......... ............................30
29 (28)- Female tail with spine
(Fig. 25)
..........................................Operculorhabditis
Female tail with broadly rounded terminus, without spine
(Fig. 26)
..................................................................................Marispelodera
30 (28)- Bursa very narrow; spicules
shorter than tail and fused at tip
(Fig. 27)...........................................................................................Bursilla
Bursa well developed; spicules longer than tail and fused at least to one third
of their length.................................................................................................31
31 (30)- Spicules fused to two third of
their length; bursa crenate in its anterior half
(Fig. 28)...............................................................................Crustorhabditis
Spicules fused to one third, sometimes one half of their length; bursa smooth
(Fig. 29)
...................................................................................Mesorhabditis
Subfamily Peloderinae:
32 (20)- Bursa closed anteriorly (Fig.
30, 31) ................................................... .........33
Bursa not closed anteriorly
...........................................................................34
33 (32)- Female tail tapering
gradually; spicules not fused;
bursa with nine pairs of ribs (Fig. 30) .....................................Caenorhabditis
Female tail narrowing suddenly with or without spike on terminus; spicules
fused;
bursa with ten pairs of ribs (Fig. 31) ............................................Coarctadera
34 (32)- Stomal tube short, about once
or twice as long as wide; cheilorhabdion cuticularized;
phasmids dot-like,very prominent (Fig.
32) ...........................Phasmarhabditis
Stomal tube normal, at least 4 times as long as wide, cheilorhabdion usually
not
cuticularized; phasmids point-like, small ..........................................................35
35 (34)- Spicules fused; bursa with ten
pairs of ribs (Fig. 33,34)
...................................36
Spicules not fused; bursa with nine pairs of ribs (Fig. 35, 37) ...........................37
36 (35)- Two first pairs of ribs not on
bursa; female tail rounded
(Fig. 33)..............................................................................Rhomborhabditis
All ribs on bursa; female tail spicate (Fig.
34) ......................................Pelodera
37 (35)- Metarhabdion each with 3 or 5
minute warts (Fig. 35) ....................Pellioditis
Metarhabdion each with 2 to 3 bristle-like denticles
(Fig. 36, 37) .................................................................................................38
38 (37)- Cheilorhabdion cuticularized;
corpus swollen (Fig. 36) ...............Xylorhabditis
Cheilorhabdion not cuticularized; corpus cylindrical
(Fig. 37).............................................................................Dolichorhabditis
Subfamily Ablechroiulinae:
39 (21)- Bursa rudimentary with 10
pairs of ribs (Fig. 38).......................Rhabditoides
Bursa narrow, but well visible, with nine pairs of ribs
(Fig. 39)
.................................................................................Ablechroiulus
Subfamily Rhabditinae:
40 (21)- Labial edges strongly
cuticularized (Fig. 40)...........................Colporhabditis
Labial edges not
cuticularized.........................................................................41
41 (40)- Stoma very short, protostom as
long as or slightly longer than wide
(Fig. 41).........................................................................................Oscheius
Stoma much longer
......................................................................................42
42 (41)- Bursa rudimentary (Fig. 42-46)
...................................................................43
Bursa normal (Fig. 47, 48) ...........................................................
..............47
43 (42)- Each spicule with long
dorsal thorn (Fig. 42-43);
metarhabdion with minute
warts...................................................................44
Spicules without dorsal thorn; metarhabdion with setose denticles
(Fig.44, 46)
................................................................................................45
44 (43)- Female tail narrowing
suddenlly to form spike; bursa
with ten pairs of ribs (Fig. 42) ......................................................Curviditis
Female tail tapering gradually to form long, finely pointed tail
(Fig. 43)..................................................................................Rhabditella
45 (43)- Amphids relatively large,
behind labial region;
bursa with 7 pairs of ribs (Fig. 44) ........................................Poikilolaimus
Amphids very small, on lateral lip; bursa with nine
pairs of
ribs.................................................................................................46
46 (45)- Nematode with cuticular
sheath; female tail short,
spikate (Fig. 45) .......................................................................Cuticularia
Nematode with normal cuticle; female tail tapering
gradually (Fig. 46) ............................................................................Rhittis
47 (42)- Bursa closed anteriorly (Fig. 47).................................................Discoditis
Bursa open anteriorly (Fig. 48) ...........................................
.........Rhabditis
Last updated 3March 2006
This document was constructed and is maintained by Khuong B. Nguyen
Entomology & Nematology Department, University of Florida.