COBB: A KEY TO THE GENERA OF FREE-LIVING NEMAS 477 



Spinneret none; cardiac bulb valvate; amphid obscure; wings and bursa present Rhabditis Duj. 1845 

 Oesophageal bulb cardiac only (for alternative see preceding page) 

 Spinneret absent; ampbid circular, elliptical or monospiral 



Head without odontia; nema not cephalated; setae 0; spear minute; in soil (Triplonchium Cobb 1920) 

 Head with 6 large odontia; bursa none or much reduced 



Nema mostly cephalated; cirri 0; amph. circular; in soil & fresh water. . . Teratocephalus de Man 1876 

 Nema not cephalated; cirri 6; amphid transverse-oval ; tail hooked; in bark Chambersiella Cobb 1920 



( = Diastolaimus Rahm 1928) 

 Spinneret present 



Pharynx simple; oesophagus not plectoid; neck 15-20% 



Cephalic setae 0; wings 0; pharynx long; amphid with pocket; tail 27% (Rhabdolaimus de Man 1880) 

 Cephalic setae 4; pharynx short; tail 15% 



Wings present; amphid monospire Paraphanolaimus Micol. 1923 



Wings absent; amphid circular; onchium minute, not at lips Prodesmodora Micol. 1923 



Pharynx compound-elongate; oes. oft with isthmus to card, bulb (plectoid); wings pres. 

 Labial region not expanded; cephalic setae usually 4, sometimes or 6; neck 12-30% 

 Cardiac bulb not valvate; pharynx long; neck 14-15%; in fresh water & mud Paraplectus Fil. 1930 



Cardiac bulb valvate; amphid circular or transverse-oval Plectus Bast. 1865 



Labial region expanded, with complicated appendages; pharynx 4-9%; neck 27-31% 

 Lips 6, distinct, revolute; striae fine; amphid semicircular; pharynx 9% (Anthonema Cobb 1906) 

 Lips not revolute; head with dorso- ventral bladders; striae coarse; amph. round; phar. 3-6% 



Cephalic appendages elaborately palmate Wilsonema Cobb 1913 



Cephalic appendages forming a closed, striated dome or cupola. .Bitholinema de Coninck 1931 

 Habitat marine or brackish (for alternative see preceding page) 



Ambulatory set. forming a ventral sole, midbody to pre-anal; nema crooked; calvarium unstriated 

 Nema narrowest in card, reg., S-shaped; ambulatory set. hollow, pre-anal; annules finer 

 Oesoph. region hardly swollen; card, bulb faint; cerv. striae alike Notochaetosoma Irwin-Smith 1918 

 Oesoph. region swollen, ovoid; oesophageal bulbs 1 or 2; band of cervical 

 striae accentuated, exc. Tristicochaeta falcatum 



Ventral ambulatory adhesion tubes or setae in 2 rows Drepanonema Cobb 1933 



( = Chaetosoma Clap. 1863) 



Ventral ambulatory adhesion tubes or setae in 3 or 4 rows Tristicochaeta Panceri 1878 



( = Draconema Cobb 1913) 

 Nema narrowest midway, epsilon-shaped; ambulatory setae not open at end; annules coarser 



Sole apparently absent; amphid cresentic; annules 98 Epsilonella Steiner 1930 



Sole present; amphid circular or monospiral 



Oesophagus with median and cardiac bulbs Metepsilonema Steiner 1927 



Oesophagus with cardiac bulb only 



Annules 80-112; ambulatory setae slender, falcate Bathyepsilonema Steiner 1927 



Annules 144-192; ambulatory setae straight or slightly arcuate 



Body cylindroid, if crooked faintly so Archepsilonema Steiner 1927 



Body epsilon-like, i.e. body arches well developed 



Cuticular annules homogeneous in structure Prochaetosoma Baylis & Daubney 1926 



( = Rhabdogaster Metsch. 1867) 

 Cuticular annules not homogeneous in structure 



"Axial" part of the cuticular annules hollow ("frame rings") Epsilonema Steiner 1927 



"Axial" part of the cuticular annules vacuolated, etc Epsilonoides Steiner 1931 



Ambulatory setae 0; nema not crooked; calvarium absent, or not truncate-conoid 

 Lips 2,mouthaslit;amph.faintmultispire;"pseudonchs"dorso-ventral ridges Pseudonchus Cobb 1920 

 Lips not 2, mouth not a slit; "pseudonchs" absent 

 Amphid multispire; neck 9-13% 

 Pharynx deeper than head width, wall irregular, with projections; striae plain Zalonema Cobb 1920 



Pharynx tubular, less deep, wall straight; striae of dots Kreisia Allgen 1929 



Amphid circular, elliptical or monospiral; neck 14-25%, exc. Bolbonema 8% 

 Wings present; anterior end set off by groove at 4 ceph. set. & usually by lack of annulation 

 Neck 20-25% 



Species marine; striae duplex; wings 2; phar. tubular, inconspic., prob. double Aplectus Cobb 1914 

 Species in brackish soil & marsh; lip reg. discoid; ceph. set. papilloid. .Leptolaimus de Man 1876 

 Neck 14-16%; marine 



Gland ducts cuticularized, piercing cuticle, cerv. and pre-anal. . Halaphanolaimus Southern 1914 

 Gland ducts & pores 0; pharynx of several long chambers; amphid round Polylaimium Cobb 1920 

 Wings absent 



Median bulb present; ceph. set. 0; amph. protruding: neck 12%; pores lateral Haliplectus Cobb 1913 

 Median bulb absent; pores none; marine 



Nema cephalated by expansion opposite large monospiral ampbid; neck 8% Bolbonema Cobb 1920 

 Nema not cephalated by expansion 



Setae on head 6-10, long, flexible; neck under 5%: pharyngeal bulb present. . (Laxus Cobb 1894) 

 Setae on head 0-4; neck 6% or over; pharyngeal bulb absent 

 Head constricted at cephalic setae, not at amphid; amphid 2 head-widths back 

 Chambers of pharynx several, long; neck 10-11%; cephalic setae 0(?) Polylaimium Cobb 1920 

 Chamber of pharynx single; neck 19%; head conoid; cephalic set. 4 Dermatolaimus Steiner 1916 

 Head not constricted at setae; amphid near lips or not over 1 head-width back 

 Ceph.set.0;phar.a tube reaching card. bulb ;amphid conspicuous. . Aegialoalaimus de Man 1907 



Amphid small.monospiral.at lips;neck 19%;dorsal phar.wall thickened (Onchium Cobb 1920) 

 Amphid conspicuous, round, not at lips;neck 6%;phar.wall not thick. .Linolaimus Cobb 1933 

 Oesophagus plain, i.e. without median or posterior bulb or swelling (for alternative see page 474) 

 Amphid not known or obscure (for alternative see next page) 

 Female not known; marine (for alternative see next page) 



Neck over 40%; amphid a long, slit; ceph. setae 4 or 8, fine; spinneret oft none. . (Halalaimoides Cobb 1933) 

 Neck 10-30%; amphid not longitudinal; spinneret present (Trileptium, Fimbriella ?) 



Cephalic setae 0; onchia 3, awl-shaped, almost parallel to axis (Fimbrilla Cobb 1905) 



( = Fimbria Cobb 1894) 

 Cephalic setae 8 or more 



Onchium dorsal,anterior,inward-pointing;neck 12%;nema0.5% wide;amph. asht (Tnleptium Cobb 1923) 



( = Trilepta Cobb 1920) 

 Onchium none; neck 22-30%; nema 2-3% wide; cephalic setae usually 8, in 2 circlets 



