KEY TO GENUS MONONCHUS 



(S. S. 455) 153 



the males are unknown (except tennis) ; female organs 

 double (except index and reverses) ; spinneret present 

 (except similis) 

 Ovary 1; tail rapidly diminished, then digitate 



Vulva behind the ovary; denticles normal 



Vulva in front of the ovary; denticles few 



Ovaries 2; tail not digitate (Ex. perhaps sigmaturus) 

 Dorsal tooth somewhat digitate, relatively small 



Refractive ring about pharynx in front of tooth 



Refractive ring about pharynx not prominent 



Dorsal tooth massive, not digitate 



Head rounded, denticles in about 12 rows 



Head truncate, denticles in 2 to 6 rows 



Rows of denticles 2 



Rows of denticles 4 to 6 



Denticles about 4 rows; spinneret small 



Denticles about 6 rows; spinneret larger 

 Tail bent ventrally near the middle 



Caudal setae none ; tail conoid 



Caudal setae (3 pairs) present; tail not conoid 

 Tail arcuate or straightish 



Width of adults 2.3 per cent 



Width of adults 2.7 per cent or more 



8audal glands and spinneret absent 

 audal glands and spinneret present 



Eggs thick shelled 



Eggs thin shelled 



Buccal striae faint if any; anus 94 to 

 96 per cent 



Species aquatic 



Species not aquatic 



Buccal striae more pronounced; anus 98 



per cent 

 Spinneret finally dorsally recurved.. 



Spinneret not dorsally recurved 



DORSAL TOOTH and others small, basal or nearly so (Exc. 44) 

 Teeth retrorse, small, basal, exceptionally midway; subg. 

 ANATONCHUS Cobb; tvpe A. tridentatus de Man; large 

 species with roomy elongated pharynx and smallish retrorse 

 teeth; tail long and usually becoming cylindroid; female 

 organs double; males of most of the species known 

 Body 2 to 4 mm.; teeth equal, midway; anus 90 per cent.... 

 Body 5 to 6 mm.; teeth sub-basal; anus 80 to 85 per cent 



Submedian teeth equaling the dorsal; body 6 mm 



Submedian teeth smaller than the dorsal; bodv 5 mm 



Teeth not retrorse, small, 9r even minute; subg. IOTONCHUS 

 Cobb; type I. gvmnolaimus Cobb: large species with roomy 

 elongated -harynx having longitudinal ribs; tail rather 

 long, and often slender; males of more than half the 

 species known: female organs double or single; most 

 species with spinneret 

 Ovary single; 1 to 3 rudimentary basal teeth 



Tail digitate; 3 sub-equal vestigial teeth 



Tail not digitate- 1 dorsal tooth, remainder faint or none 



Posterior extremity setaceous 



Posterior ext-mity slender but not setaceous 



Pharynx as long as wide; few submedian denticles... 

 Pharynx about 2 times long as wide; faint submedian 



teeth 

 Amphid simnle; buccal wall thin, transversely striated 



Amphid duplex; buccal wall thick, not striated 



Ovaries 2; 1 t" 3 small, sub-basal teeth 



Body 4 to 7 mm.; tail finally cylindroid; 3 teeth 

 Spinnerer present; lips rather plain 



Length 4 mm.; anus 90 per cent; the 3 teeth subequal 

 Length 6 to 7 mm.; anus 80 per cent; submedian teeth 



smaller 



Spinneret none; lips striated lengthwise . . ._ 



Body 1 ti 4 mm.; tail conoid; 1 tooth, sometimes denticles 

 Anus .-* about 86 per cent; tail conoid, or at last sub- 



cylindroid 

 Lips not set off by constriction; onchi unequal or one 



Onchus with small companions; head rounded 



Onchus one only; head truncate; pharynx striated... 

 Lips set off by a deep constriction; onchi three, equal 

 Anus at about 94 per cent; tail simply conoid 



Dorsal tooth small, others basal, minute, indefinite. . . . 

 Dorsal tooth distinct 



Buccal cavity half as wide as long: tooth sub-basal.. 

 Buccal cavity as wide as long; main tooth basal 



Spinneret present 



Spinneret none 



4. MYLONCHULUS 



index Cobb 1907 

 reversus n. sp. 



obtusicaudatus Daday 1901 

 brachyuris Biitschli 1873 



denticulatus n. sp. 

 sparsus n. sp. 

 micrurus n. sp. 



incurvus n. sp. 

 sigmaturus n. sp. 



subtenuis n. sp. 

 subsimilis n. sp. 

 obliquus n. sp. 



lacustris Cobb 1915 

 polonicus Stefanski 1915 

 minor Cobb 1893 



brevicaudatus n. sp. 

 japonicus n. sp. 



ANATONCHUS 



tridentatus de Man 1876 



gracilicaudatus n. sp. 

 dolichurus Ditlevsen 1911 



6. IOTONCHUS 



digiturus Cobb 1893 



trichurus n. sp. 



(bathybius Micoletzky 1913) 



gvmnolaimus Cobb 1893 

 consimilis n. sp. 



rex Cobb 1904 

 regius n. sp. 



bathybius Micoletzky 1913 

 similis Cobb 1893 

 fasciatus n. sp. 



studeri Steiner 1914 

 zschokkei Menzel 1913 



brachylaimus n. sp. 

 acutus n. sp. 



