COBB: A KEY TO THE GENERA OF FREE-LIVING NEMAS 469 



"Spear" a minute prod between lips; cephalic setae ..................... Demaniella Steiner 1914 



( = .Demania Steiner 1914) 



Spinneret present, exc. sometimes in Mononchue 

 Amphid spiral; pharynx iconoid ........................................... Nannonchus Cobb 1913 



Amphid circular or oval, often small, with internal pocket 

 Pharynx irregularly conoid ; onchia small ........................................ Trilobus Bast. 1865 



Pharynx not conoid; one or more onchia large 

 Lips thick; papillae 12, in 2 circlets; renette not known ................... Mononchus Bast. 1865 



Lips thin; papillae 6, ceph. set. 10; renette pres., ampulla conspicuous ..... Adoncholaimua Fil. 1908 



Habitat marine; spinneret usually present (for alternative see preceding page) 

 Cuticle annulated 



Annules not resolvable into dots or rod-like elements 



Head truncate; annules interrupted; ceph. set. 4 ; phar. ribs long. , serrate . . Rhabdotoderma Marion 1870 

 Head rounded; annules plain; setae many, short, iirregular on calvarium. . . .Croconema Cobb 1920 



Annules of rod-like marks; pharynx cyatholaimoid, vestibule ribbed; amphid a transverse slit 

 Ceph. set. 4, labial papillae setose; annules plain laterally ..... Dicriconema Steiner & Hoeppli 1926 



Ceph. set. 10; annules with V-shaped marks laterally, "basket-work" on neck. . ..Rhips Cobb 1920 



Cuticle not annulated; striae if present very fine 



Head wjth subcuticular calvarium; amphid with internal pocket; Enoplidae 

 Calvarium complex, ornate, long-conoid .................................. Thoracostoma Marion 1870 



Calvarium relatively simple, a band with undulating margins; glands lateral 



Pharynx wide; lips with denticles; odontia present(?); nema 20-34 mm.. .Cylicolaimus de Man 1889 

 Pharynx narrow, filled by onchia, dorsal largest; cervical setae many; nema 8-17 mm. 

 Odontia present; cephalic setae long ........................................ fiacra Southern 1914 



Odontia absent; cephalic setae short or medium ............................. Synonchus Cobb 1894 



( = Jagerskioldia Fil. 1916) 

 Head without calvarium 

 Amphid spiral; pharynx small, irregularly conoid, vestibule ribbed ........ (Chromaspirina Fil. 1918) 



( = Mesodorus Cobb 1920) 



Amphid with internal pocket; pharynx large, open, squarish, ribbed vestibule absent 

 Pharynx not divided, walls ithick; amph. small ; excretory pore oft not at lips; Oncholaiminae 

 Demanian system present, with exit pores and developed uvette ........ Adoncholaimus Fil. 1918 



Demanian system absent, or gonenteric duct only 

 Subventral onchia equal in size; amphidial opening longer than wide 

 Tail 33%, filiform, spinneret none; gubernaculum none ................. Filoncholaimus Fil. 1927 



( = Pseiidoi>aroncholaimus Kreis 1932) 

 Tail short, rounded ; gubernaculum present ............................... Pontonema Leidy 1855 



^=Paroncholaimus Fil. 1916) 



Subventral onchia unequal in size; pharynx depth twice its width or more 



Cuticle not viscous; phar. bulb clavate; lip reg.set off by coastriction . .Steinvriella Allgen 1932 



( = Steineria Ditlev. 1928) 



Cuticle viscous; pharyngeal bulb none; nema under 3 mm.; tail 6-10% 



Pharynx very deep, ifilled by subventral onch.; bursa present Oncholaimellus de Man 1890 

 Pharynx not over twice as deep as wide, not filled by onchium; bursa none 

 Dorsal wall of pharynx well developed ............................ Viscosia (de Man) Fil. 1918 



Dorsal wall of pharynx rudimentary, an extension of dorsal tooth ---- Meroviscosia Kreis 1932 



xcretory pore oft at lips; large onch. subventral 



Pharynx 2-5 chambers, wall thin; amph. large; exc 

 Oesophageal bulbs 5-8, serial, contiguous 

 Amphidial opening transverse, slit-like; a" s 



supplements eurystomoid ...... Bolbflla Cobb 1920 



Amphidial opening ^circular; cf an enchelid, supplements simple. .Polygastrophora de Man 1922 

 Oesophageal bulbs none 



External amphid transverse, slit-like; pharynx usually square; caudal glands before anus 

 Denticles forming a broad mid-pharyngeal band; d" supplements simple. . . Thoonchus Cobb 1920 

 Denticles in 1-3 rows; d" supplements complex, "fluked" ............. Eurystomina Fil. 1921 



( = Eurystoma Marion 1870 

 = Marionella Cobb 1922) 



External amphid round; pharynx deep; onch. spear-like, exc. Ditlevsenella; cf oft an enchelid 

 Anterior oesophagus narrower, lumen wide .......................... Calyplronema Marion 1870 



( = Ca(aIaimiu Cobb 1920) 

 Anterior oesophagus not differentiated 

 Large onchia 3 ...................................................... fenestrolaimus Fil. 1927 



Large onchium 1, other onchia 2 

 The large onchium conoid; nema 4-6 mm ............................. Ditlevsenella Fil. 1927 



The large onchium long, slender, spear-like 

 Pharyngeal chambers behind vestibule 2; eyes 2 .......................... Dilaimus Fil. 1927 



( = Amphistenus Marion 1870) 



Pharyngeal chambers behind vestibule more than 2 

 Chambers separated by 2-4 rings or by dots or denticles ............ Symplocostoma Bast. 1865 



Chambers (first 2) separated by "commas"; rings 3; eyes 6 ..... Symplocostomella Micol. 1930 



