COBB: A KEY TO THE GENERA OF FREE-LIVING NEMAS 471 



Spinneret present; striae of dots; phar. denticulate; post, ovary undev.; marine Dasylaimus Cobb 1933 

 Spinneret absent; pharynx not denticulate; not marine 

 Head with 6 biting odontia; amphid round; nema cephalated exc. 



Teratocephalus palustris ........................... Teratocephalus de Man 1876 



Head with entire or 3-parted lip region; amphid small, at lips; nema not 



cephalated, exc. Acrobeles insubricus 

 Probolae absent ; cephalic appendages or in 1 circlet ....................... Panagrolaimus Fuchs 1930 



Probolae present; in soil 

 Cephalic appendages in 2 circlets .............................................. Acrobeles Linst. 1877 



Cephalic appendages in 1 circlet ............................................. Cephalobus Bast. 1865 



( = Acrobeloides (Cobb) Steiner & Buhrer 1933) 

 Ovaries 2 (for alternative see preceding page) 

 Gonads 9 outstretched 



Amphid multispire; striae fine; pharynx small, cup-shaped 



ale ventral pre-anal supplementary organs small ....................... (Parasabatieria de Man 1907) 



Male supplementary organs none ...................... ." ................. (Sabatieria de Rouville 1903) 



Amphid circular 



Pharynx obconoid, cutic. rings 1 or more; spinneret pres.; brackish soil. . . (Desmolaimus de Man 1880) 

 Pharynx without transverse cuticularized rings; spinneret present or not 

 Habitat not marine; cephalic setae 

 Spinneret present; head with 4 circular "warts" ; in fresh water ......... Pseudochromadora Daday 1901 



Spinneret absent; head without "warts"; bursa present; in moss .......... Himatidiophila Rahm 1925 



Habitat marine; striae fine; cephalic setae present 

 The pharynx obconoid, with cylindroid vestibule 



Base pharynx cuticularized; head icylindroid; cardiac bulb valvate. . Metalinhomoeus de Man 1907 



(cf. Deltane.ma Kreis 1929) 



Base pharynx not cuticularized; head conoid; lips if everted knob-like Cryptolaimus Cobb 1933 

 The pharynx minute or none 



Cardiac swelling not strongly developed; ceph. set. 8-10; nema not tapering Linhomoeus Bast. 1865 

 Cardiac bulb broad, valvate; ceph. set. 4; nema tapering, tail setaceous Terschellingia de Man 1888 

 Gonads 9 reflexed 

 Habit parasitic, in insects; oesophagus without median bulb ............. Neoaplectana Steiner 1929 



Habit free-living 



Spinneret absent; cephalic setae 0; in soil and fresh water 



Nema cephalated, exc. T. palustris; lip reg. lobed, with 6 biting odontia. . Teralocephalus de Man 1876 

 Nema not cephalated; lip region not lobate; bursa present ................ Himatidiophila Rahm 1925 



Spinneret present 

 Cephalic setae 0; head with 4 circular "warts"; in fresh water ............ Pseudochromadora Daday 1901 



Cephalic setae present; head without "warts" 

 Habitat fresh water or soil; amphid circular to monospiral ...................... Plectus Bast. 1865 



Habitat marine 

 Lips 2, mouth a dorso-ventral slit; "pseudonchs" dorso- ventral ridges. . . . (Pseudonchus Cobb 1920) 



Lips more than 2. mouth not a slit; "pseudonchs" absent 

 Amphid multispire 

 Pharynx irregular, with tooth-like projections .............................. Zalonema Cobb 1920 



Pharynx simply conoid, regular, without tooth-like projections 

 Head set off by absence of striae .................................. Heterodesmodora Micql. 1924 



Head not set off; striae extending to lips; neck 6-7%; onchium minute ....... Spirina Fil. 1918 



( = Spira Bast. 1865) 

 Amphid circular or monospiral 



The pharynx denticulate ; post, ovary undev. ; stria* of dots; wings pres. . . (Dasylaimus Cobb 1933) 

 The pharynx not denticulate; both ovaries developed 

 Dorsal pharyngeal wall not thickened; amphid not at lips 



Neck 14-21%; wings present; amphid long-oval; head set off by groove at 4 cephalic setae 

 Length of neck 14-16%; amphid large, head-width back .......... Eutelolaimus de Man 1922 



Length of neck 21%; amphid 2 head-widths back .......................... Aplectus Cobb 1914 



Neck under 7%; wings 0; amphid spiral 



Nema 4-7 mm.; width 0.3-1%; phar. straight, closed, with pharyng. swelling Laxus Cobb 1894 

 Nema 2-4 mm.; width 1.5-4%; pharynx conoid, oft with small onchium ...... Spirina Fil. 1918 



(=Spira Bast. 1865) 



Dorsal pharyng. wall thick, tooth-like; amph. monospire at lips; ceph. set. 4 ; renette far back 

 Oesoph. glands obscuring junct. of intest.; dorsal phar. element dbuniform 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 



( = Digitonchvs 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 



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 marine; lip region discoid; odontia 6; ceph. set.4; amphid small ..... (Stephanolaimus Ditlev. 1918) 



Habitat fresh water, marsh or sand 



Hemispherical "cap" wider than neck, edge setose; phar. conoid; spinneret pres. Diplolaimus Linst. 1876 

 Hemispherical cap none; setae 0; spinneret 0; wings double; bursa striate. . . .Macroposthonia de Man 1880 



Female known; spinneret present 

 Ovary 1; marine 



Gonad 9 reflexed; ceph. set. 0, pharynx denticulate; post, ovary undev.; wings pres. Dasylaimus Cobb 1933 

 Gonad 9 outstretched ; cephalic setae 4 

 The ovary anterior; nema 3 mm.; neck 12%,; vulva 75% ........................ Krampia Ditlev. 1922 



The ovary posterior; nema 1 mm. ; neck 19%; vulva 35% ....................... Asymmetrica Kreis 1929 



Ovaries 2, reflexed 



Habitat fresh water (for alternative see next page) 

 Lips 3, rounded; pharynx small, closed; onchium minute, deepset .................. (Tripyla Bast. 1865) 



( = Promononchus Micol. 1923) 



