12i|. 



Genus Axonchj-um Cobb, 1920 

 (Key to the species modified from Thome, 1939) 



1. Anterior female sexual branch normal 2 



Anterior female sexual branch rudimentary or absent 3 



2. Length \inder 2.0 mm . . . . mai^nicollis (Cobb, 1906) Th. & Swang., 1936 

 Length near 3.0 mm, , . . ♦ longicollis (Cobb, 1893) Th. & Swan?., 1939 



3.1 Inner portion of lips subspberical . . . . . . . labiatum Thome, 1939 



Inner portion of lips conoid, hemispherical, or obscure , U 



h» Lip region completely amalgamated, head bluntly conoid; length 1.0 mm. 

 .. o o ...... o . c o .......... . amalgans Thorne, 1939 



Lip region not completely amalgamated^ lenefth about 1.5 rnm or over 

 5 



5. Amphids forming a deep pocket completely surrounding lips 6 



Amphids not forming a deep pocket completely surro\mding lips ... 7 



6. Length over U.O mm. , , gigas Thorne, 1939 



Length under 3.0 mm .,....,., ,. micans Thome, 1939 



7. Length about 1,5"™.. .......... 8 



Length about 2.5 mm or more ........... 9 



8. Anterior fem.ale sexual branch as long as posterior; male known; 

 spicula very long .., e ........ . macrophallxm Thome, 1939 



Anterior female sexual branch a short pouch; males apparently non- 

 existent .............. amplicolle Cobb, 1920 



9. Inner portion of lips somewhat conoid; length about U.O mm; males 

 luiknown 10 



Inner portion of lips low, rounded, more obscure; length under ij.O mm; 

 males generally known 



10. Cuticle near head with prominent striae 



......... o ..... c coronatum (de Man, 1906) T. & S., 1936 



Cuticle near head not prominently striated. . . . eras sum Thome, 1939 



11. Anterior uterine branch only about twice as long as body width, males 



non-existent. .,..., , 12 



Anterior uterine branch four times body width or more, males known 

 13 



12, V = UU^ , ,.,.,,., so litare Thome, 1939 



V = 58-60/u ,,,.,o.. ..,,,,. leptocephalus Altherr, 1953 



13, Supplement series anterior to spicula . . ih 



Supplement series beginning within range of spicula , ,- l5 



111, Supplements adjacent to one another choristum Thome, 1939 



Supplements spaced. . . , , , tenuicollis (Steiner, I9IU) T, & S, 1939 



