COBB: A KEY TO THE GENERA OF FREE-LIVING NEMAS 465 



Median oesophageal bulb not swollen; ceph. set. 0; striae plain (Odontopharynx de Man 1912) 



Median oesophageal bulb swollen; cardiac swelling non-valvate 



Pharynx i wide as deep; ceph set. present; tail setaceous; bursa 0. . ..Diplogaster M. Schultze 1857 

 Pharynx narrow, posterior tubular portion not over 1 as wide as deep; ceph. set. 



Onchium basal; tail conoid then setaceous; bursa none Diplogasteroides de Man 1912 



Onchium anterior; striae of dots; tail conoid; bursa rhabditoid Neodiplogaster Cobb 1924 



Spinneret present, exc. sometimes Spirina (for alternative see preceding page) 



Oesophageal bulbs 5-8, serial, contiguous; cf an enchelid; marine Polygastrophora de Man 1922 



Oesophageal bulb 1 



Anterior oesophagus narrow, lumen wide; marine Calyptronema Marion 1870 



( = Catalaimus Cobb 1920) 

 Anterior oesophagus not differentiated 

 Wings present 



Pharyngeal bulb set off by constriction; wings 12, bristles retrorse; marine. . .Rhinema Cobb 1920 

 Pharyngeal bulb none or confluent 



Nema cephalated by cuticular change & by expansion; cardiac bulb short, not divided 

 Head "punctate" ; wings 12-18; ceph. set. 6; denticles pres. ; amph. spiral Desmodorella Cobb 1933 

 Head plain;wing l;ceph.set.0;denticles 0;amph.round;caud.gl'nds pre-anal Xenonema Cobb 1920 

 Nema not cephalated; cardiac bulb long, 2- or 3-zoned; amphid spiral 



Striae of dots; wings scalariform; cf supplements Spilophorium Cobb 1933 



(-SpOopkom Bast. 1865) 

 Striae plain 



Cephalic setae many, jointed; c? pre-anal cuticle thickened Neonyx Cobb 1933 



Cephalic setae 4, short; wing 1; cf supplements post-anal Metachromadara Fil. 1918 



( = Ckromadoropsis Fil. 1918) 



Wings 0; striae not altered laterally, exc. sometimes Desmodora 

 Habitat freshwater; minute subordinate onchia usually present 



Pharynx behind onchia parallel-sided; pharyngeal bulb definite Elhmolaimus de Man 1880 



Pharynx behind onchia iconoid; pharyngeal bulb absent 



Amphid spiral; cephalic setae usually 10; pharynx open, irregular Achromadora Cobb 1913 



Amphid circular; cephalic setae 4; pharynx often obscure Prodesmodara Micol. 1923 



Habitat marine 

 Dorsal pharyngeal wall thickened, onchium-like; amphid monospire 



at lips; cephalic setae 4; renette far back 



Oesoph. glands obscuring junction of intest.; dorsal phar. element iuniform Onchium Cobb 1920 

 Oesoph. glands not prominent; dorsal pharyng. element not uniformly thick, but heavy 



Tooth-like thickening parallel to axis Camacolaimus de Man 1889 



( = Digitonchus Cobb 1920 

 = Acontiolaimus Fil. 1918) 

 Tooth-like thickening bent outward from beginning of vestibule 



Point of "onchium" single Acmaeolaimus Fil. 1918 



Point of Y-shaped "onchium" duplex Ypsilon Cobb 1920 



Dorsal pharyngeal wall not thickened; onchium a distinct projection 

 Cephalic setae 12-26; cardiac bulb elongate; amphid spiral 



Striae of dots, on head also; labial papillae setose; ceph. set. 12 Bradylaimus Stekhoven 1931 



Striae plain, absent on head; cephalic setae 24-26; amphid monospire 



Pharynx denticulate; onch. sigmoid ventrally ; of 1 supplements sigmoid Sigmophora Cobb 1933 

 Pharynx not denticulate; onch. not sigmoid; cf supplements papilloid Xanthodora Cobb 1920 

 Cephalic setae 4 

 Striae of dots 



Dorsal onchium large, basal; pharyngeal bulb stronger dorsad Odontonema Fil. 1930 



Dorsal onchium anterior; pharyngeal bulb isymmetrical Chromadorina Fil. 1918 



Striae plain 



Head set off by lack of striae; pharynx & onchium inconspic. ; marine. . Desmodora de Man 1889 

 Head not set off; striae extending to lips 



Pharyngeal bulb 0; cardiac bulb short; onchium minute; neck 6-7% Spirina Fil. 1918 



(=Spira Bast. 1865) 

 Pharyngeal bulb present; cardiac bulb long, massive, 2- or 3-zoned; neck over 12% 



Onchium spear-like; head rounded Onyx Cobb 1891 



Onchium not spear-like; head truncate Metachromadora Fil. 1918 



( = Chromadoropsis Fil. 1918) 



Teeth (onchia or odontia) 2 or more (for alternative see page 461) 



Oesophagus with median or posterior bulb or swelling, or both (for alternative see page 467) 

 The teeth equal in size, usually mobile radially (for alternative see next page) 

 Stroke of teeth outward; amphid often obscure (for alternative see next page) 

 Spinneret absent; '9 or ' 9 ' 



Cardiac bulb valvate; cuticle without longitudinal striae Diploscapter Cobb 1913 



Cardiac bulb not valvate, median bulb valvate; cuticle with longitudinal striae 



Posterior pharyngeal chamber behind onchia; lips with radiate framework Mononchoides Rahm 1928 



Posterior pharyngeal chamber absent; lips without radiate framework Diplogaster M. Schultze 1857 



(=Pristionchus Kreis 1932) 



Spinneret present; median oesophageal bulb absent 

 Pharynx tubular, 4-6% of body length 



Amphid long, reaching base of pharynx or mid-body ; odontia 6, minute ; - 9 ~ Pseudolella Cobb 1920 



Amphid small, at lips, with pocket; odontia 3, massive; tail oft striate; ' 9 ' Syringolaimus de Man 1888 



Pharynx conoid, not over 2% of body length 



Odontia ;onch . 3 , at base shallow phar. ;amph . round ; card, swelling obvious r 9 A ponchium Cobb 1920 

 Odontia 6 or 12;onch. 0;amph. bent or crook-shape;card. bulb or weakr9~ Odontophora Butech. 1874 



( = Trigonolaimus Ditlev. 1918 

 = Conolaimus Fil. 1918) 

 Striae of dots; cardiac swelling obvious 



Amphid spiral ;onch.3,curved; cf 1 supplements or papilloid; gubernac.O; cf only. . Statenio Allgen 1930 

 Amphid a transverse slit, near lips; ' 9 ' 



Lateral fields marked by longitudinal rows of larger dots Chromadorella Fil. 191: 



Lateral fields without longitudinal rows of larger dots Prochromadorella Micol. 1924 



