COBB: A KEY TO THE GENERA OF FREE-LIVING NEMAS 457 



External amphid spiral, circular or elliptisal (for alternative see preceding page) 

 Female not known; spinneret present 



Habitat brackish earth; wings faint; d" supplements on neck, ventral, papilloid Deontolaimus de Man 1880 

 Habitat marine 



Annules 90, prominentjsubdorsal setae 9 prs. ;amph. saccate; nema 10% + wide Eudesmoscolex Steiner 1916 

 Annules none or not prominent; subdorsal setae 0; amphid not sacsate; nema under 5% wide 



Wing small, distinct; amphid almost neck width, joined dorsad (Antomicron Cobb 1920) 



Wings absent 

 Mouth and digestive system vestigial; setae strongly developed 



Eyes absent Barbonema Fil. 1927 



Eyes and amphid strongly developed ; adult cf only (Enchelidium Ehrenb. 1836) 



( = Lasiomitus Marion 1870 

 =Parasymplocostoma Schulz 1932) 

 Mouth and digestive system functional 



Odontia 6, minute; cephalic setae 10(7), subcephalic 4, jointed Apodonlium Cobb 1920 



Odontia 0; cephalic setae or rather small 



Annules rather coarse; setae minute; amphid transverse-oval (Zygonemella Cobb 1920) 



Annules and striae none; amphid with internal pocket 



Cephaljc setae 0; amphid long-oval, internal pocket conspicuous Schislodera Cobb 1920 



Cephalic setae small, 10; cervical setae lateral; amphid small, round . . . . (Leptosomalides Fil. 1918) 

 Female known 



Ovary 1 ; amphid not multispire 

 Gonad 9 outstretched 

 The ovary posterior; spinneret present 



Amphid large, open caudad; spinneret sometimes doubtful; marine (Alaimella Cobb 1920) 



Amphid round; anterior ovary rudimentary; ceph. set. 12, in 2 circlets; in salt marsh Litinium Cobb 1920 

 The ovary anterior; marine 



Pharynx absent; setae 4, papilloid ;amph. small, open caudad; spinneret 0; among algae Litotes Cobb 1920 

 Pharynx present, often minute; setae not papilloid ; amphid larger, circular; spinneret sometimes 



Onchia 0; nema small Monhystera Bast. 1865 



( = Tacky hodites Bast. 1865) 



Onchium dorsal; nema often several millimetres long Linhomoeus Bast. 1865 



( = L. obtusicaudatus de Man 1907) 

 Gonad 9 reflexed 

 Habitat soil or fresh water, or in insects; amphid circular 



The ovary posterior; spinneret absent; in marshy soil Alaimus de Man 1880 



The ovary anterior 



Spinneret present ; in fresh water Helalaimus de Cillis" 1917 



Spinneret absent; in beetle, Passalus Chondronema Christie & Chitwood 1931 



(=Uracanthus Dies. 1861) 



Habitat marine; ovary posterior; spinneret present (Alaimella ?) 

 Cephalic setae 



Amphid monospire; in sand about algae Nemanema Cobb 1920 



Amphid long-oval, with posterior cuticularized pocket Schistodera Cobb 1920 



(cf. Oxy stamina Fil. 1921) 

 Cephalic setae present 



Setae on head 4, over 1 head-width long; striae coarse; amphid large, open caudad. . Alaimella Cobb 1920 

 Setae 10 or 16, 4 being subcephalic; striae or fine 



External amphjd circular; cephalic setae 12, as long as head is wide Lilinium Cobb 1920 



External amphid oval, pocket cuticularized; cephalic setae 6 (4?) 



Amphidial opening small transverse-oval, or circular Nemanemella Fil. 1927 



Amphidial opening large, long-oval Oxystomina Fil. 1921 



( = Oxystoma Butsch. 1874) 

 Ovaries 2 



Gonads 9 outstretched; marine 

 Spinneret absent 



Pharyngeal bulb definite; ceph. setae 6, stout, jointed; amphid circular; in sand (Cytolaimium Cobb 1920) 

 Pharyngeal bulb absent 



Tail 3%, eonoid; ceph. set. 10; cervical long, bunched; amphid transverse-oval Platycoma Cobb 1894 



Tail over 12%, conoid then cylindroid; ceph. set. minute, 18, in 3 circlets (Anticyathus Cobb 1920) 



Spinneret present 



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



Gland ducts and pores absent 



Annules few, very coarse; amphid saccate; cephalic setae 4; nema wide 



Number of annules 17, secreted annules prominent, separated; head small. . .Desmoscolex Clap. 1863 

 Number of annules 32-91 , secreted annules none; head concave-quadrate pyramidal Tricoma Cobb 1894 



( = Quadricoma Fil. 1922) 



Annules if present not coarse; amphid not saccate 

 Ampbid multispire 



Cephalic setae 10, shorter 4 specialized at tips; multispire faint; neck 5% Linhomoella Cobb 1920 



Cephalic setae without specialized tips; multispire distinct; neck 9-16% 



Male ventral pre-anal supplementary organs papilloid Parasabatieria de Man 1907 



Male ventral pre-anal supplementary organs absent Sabatieria de Rouville 1903 



Amphid circular (Southernia slightly irregular) 



Oesoph. & lumen with ellipsoid enlargement behind eyes; eyes sometimes Araeolaimus de Man 1888 

 Oesoph. without median enlargement; eyes 

 Cephalic setae 4; amphid slightly irregular Southernia Allgen 1929 



Lips distinct; pharyngeal bulb pres.; ceph. set. 6, stout, jointed; papillae 6. .Cytolaimium Cobb 1920 



Setae on head 10, shorter 4 specialized at tips; multispire faint (Linhomoella Cobb 1920) 



Setae on head without specialized tips; amphid circular Linhomoeus Bast. 1865 



Gonads 9 reflexed 

 Spinneret absent; amphid circular, elliptical or monospiral; wings (for alternative see next page) 



Habitat soil ; internal amphid conspicuous (Basliama de Man 1876) 



Habitat marine 

 Tail 40%; vulva 33%; ceph. set. 6, subceph. 6; internal amphid conspicuous. ... Trefusia de Man 1893 



