COBB: A KEY TO THE GENERA OF FREE-LIVING NEMAS 455 



Oesophagus narrowed from middle ; cephalic setae 4 ; amphid large ; head narrowed Cyartonema Cobb 1920 

 Oesophagus not narrowed; cephalic setae present; wings 

 Setae on head 10, 4 short specialized at tip; cardiac swelling slight ............ (Linhomoella Cobb 1920) 



Setae on head 4-8, less than 1 head-width long, tip not specialized; amphid circular 

 Pharynx 0;nema small, tapered ; card, bulb broad, valvate; tail setaceous.. Terschellingia de Man 1888 

 Pharynx present though obscure 



Ceph. set. 8-10; card, swelling none or clavate, non-valvate; nema not tapered Linhomoeus Bast. 1865 

 Ceph. set. 4;cardiac bulb pyriform, sometimes valvate; pharynx obconoid (Cryptolaimua Cobb 1933) 

 Gonads 9 reflexed; amphid circular, oval or monospiral (for alternative see preceding page) 

 Spinneret none; amphid a pore at lips; ceph. set. 2, minute; in beetle larvae. . . (Neoaplectana Steiner 1929) 

 Spinneret present; marine exc. Haliplectus 



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



Med. oes. bulb pres.; ceph. set. 0; pores in submed. rows; water & brackish soil.. (Haliplectus Cobb 1913) 

 Med. oes. bulb absent; marine 



Gland ducts cuticularized, pores cerv. & pre-anal; striae coarse. .. (Halaphanolaimus Southern 1914) 

 Gland ducts and pores none or not cuticularized 

 Head expanded opposite monospiral amphid; cephalic setae 4 .................. Bolbonema Cobb 1920 



Head not expanded 

 Cephaljc setae 0; wings 0; head narrowed from amphid forward ....... Aegialoalaim.ua de Man 1907 



Cephalic setae present; often in coastal sand 



Amphid oval, 1 head-width long; annules fine; wing single; ceph. set. 4..Eutelolaimus de Man 1922 

 Amphid iequidiametral, less than i corresponding neck width 



Neck 21%; striae duplex; wings 2; ceph. setae 4; pharynx narrow, inconspicuous Aplectus Cobb 1914 

 Neck 7% or less; striae not duplex; wings 



Cuticle annulated; amph. small, at lips; set. on head many, in circles of 4..(Stilbonema Cobb 1920) 

 Cuticle finely striated; amphid 1 to i head-width, often monospiral 



Pharynx straight.closed.with pharyng.swelling; nema 4-7 mm.; width 0.3-0.8% Laxus Cobb 1894 

 Pharynx conoid, often with small onchium; nema 2-4 mm.; width 1.5-3.5% Spirina Fil. 1918 



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

 Nema narrowest in cardiac region, S-shaped; ambulatory setae hollow, pre-anal; annules finer 

 Oesoph. region hardly swollen; card, bulb faint; cervical 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 3 or 4 rows ................. Tristicochaeta Panceri 1878 



( = Draconema Cobb 1913) 

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



( = Chaetosoma Clap. 1863) 



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

 Sole apparently absent; amphid crescentic; 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 Metech. 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 



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

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

 Female not known 



Habitat freshwater marshes ; setae 0; spinneret none; neck 15-25%; wings double Macroposthonia de Man 1880 

 Habitat marine 

 Neck 8%, cylindroid; cephalic setae 4(?); tail cylindroid ............................. Nuadella Allgen 1927 



Neck 16-43%, itapering; tail conoid 

 Spinneret absent; eyes 0; neck 40%; cephalic setae 4 or 8 ................... (Halalaimoides Cobb 1933) 



Spinneret present; eyes with lenses; neck 16-25% 

 Cep 



phalic setae 4 ; head set off by cessation of very fine striation ...................... Nemella Cobb 1920 



Cephalic setae 10; striae none; amphid and setae very large; adult cf only ..... Enchelidium Ehrenb. 1836 



(=Lasiomitus Marion 1870 

 = Parasymplocostoma Schulz 1932) 

 Female known 



Ovary 1, anterior exc. Antopus & Thalassoalaimus (for alternative see next page) 



Gonad 9 outstretched; setae 4, papilloid ; amphid minute, open caudad; marine algae. . .(Litotes Cobb 1920) 

 Gonad 9 reflexed; spinneret none, exc. Antopus & Thalassoalaimus 

 Cephalic setae 6; posterior ovary longer than anterior; marine 

 Pores in dorso-lateral rows ........................................................... Antopus Cobb 1933 



Pores none ................................................................ Thalassoalaimus de Man 1893 



Cephalic setae 0; vulva near anus; spicula 2; in and around insects 

 Spear none or vestigial 

 Uterus not evaginated 



Nema serpentine; oesophagus and intestine persisting; in beetles and weevils. . .Bradynema Strass. 1892 

 Nema saccate; organs degenerating exc. gonads ............................... Allantonema Leuck. 1884 



( = TylenchomarphusFucbs 1914) 



Uterus finally evaginated; oesophagus and intestine degenerating early 

 Evaginated uterus many times as large as nema .............................. Sphaerularia Duf . 1837 



Evaginated uterus not much larger than nema .................................. Asconema Leuck. 1886 



( = Atractonema Leuck. 1887) 



Spear present, at least in larva or 9 ; organs degenerating in adult 



Base of spear ibulbed ; oes. fusiform, glands abs. in a" ; bursa pre- and post-anal . . Scatonema Bovien 1932 

 Base of spear straight; spicula nearly straight 



Vulva degenerating; 9 free living; bursa pre-anal; in Passalus. .Chondronema Christie & Chitwood 1931 



(=Uracanthus Dies. 1861) 



