ONCHOLAIMINAE 117 



15. Mononchus Bastian, 1865. 



Syn. Onchulus Cobb, 1920; Promononchus Micoletzky», 

 1923. 



Cuticle unstriated and without bristles. Head not distinct, 

 with or without papillae, without bristles. Lateral organs 

 small, indistinct. Pharynx large, more or less oval, with a 

 dorsal tooth projecting from its wall into the lumen, and 

 frequently with two smaller sub ventral teeth. Small denticles 

 may also be present on the ventral wall of the pharynx. 

 Oesophagus without bulb, but slightly swollen posteriorly. 

 Caudal end of male with a ventral row of eight to twenty 

 supplementary organs, and with preanal and postanal papillae. 

 Two accessory pieces present. Testes paired, opposed, 

 outstretched. Female genital tubes usually paired, opposed, 

 reflexed. Many species probably hermaphrodite. Caudal 

 glands and spinneret present. 



Hab. Soil or fresh water. 



Genotype : 31. truncatus Bastian, 1865. 



Bastian, 1865, Trans. Linn. Soc. London, xxv, 100; Cobb, 

 1916, Journ. Parasitol., ii, 196; 1917, Soil Science (May), 

 184, j^r. \Contr. Sci. Nematol., vi, 129, j^f.]. 



Onchulus Cobb and Promononclnis Micoletzky were both 

 described from single immature specimens, and are insuffi- 

 ciently characterized to separate them from Mononchus. 



Cobb (1916 and 1917) divides the genus Mojionchus into the 

 following subgenera : 



a. Mononchus. 



Dorsal tooth large, midway or further forward in the 

 phar5rnx. Sub ventral teeth present or absent. Ventral 

 denticles absent. Type : truncatus Bastian, 1865. 



b. Prionchulus Cobb, 1916. 



Dorsal tooth large, midway or further forward in the 

 pharynx. Subventral teeth apparently absent. Ventral 

 denticles arranged longitudinally. Type : muscorum 

 Dujardin, 1845. 



c. Anatonchus Cobb, 1916. 



Dorsal tooth and subventral teeth small and back- 

 wardly-directed, at about the middle of the pharjTix 

 or behind it. Denticles apparently absent. Type : 

 tridentatus de Man, 1876. 



d. lotonchus Cobb, 1916. 



Dorsal tooth always at the base of the pharjoix. The 

 subventral teeth may be very small. Ventral denticles 

 apparently absent. Type : gymnolaimus Cobb, 1893. 



