Bull. Mus. nain. Hist. nat., Paris, 4 e sér., 2, 1980, 
section A, n° 3 : 707-718. 
A révision of the genus Oxysomatium Railliet & Henry, 1916 
(Nematoda, Cosmocercidae) 
by Michael R. Baker * 
Résumé. — Révision du genre Oxysomatium Railliet y Henry, 1916 (A émaloda, Cosmocer- 
cidae). — Le genre Neoxysomatium Bal les teros-Marquez, 1945, est synonyme d’ Oxysomatium 
Railliet & Henry, 1916 ; ces deux genres ont la même espèce-type. Oxysomatium comprend trois 
espèces : O. brevicaudatum (Zeder, 1800) [= O. contortum (Linstow, 1906) Baylis, 1927 ; = O. longe- 
spiculum Railliet & Henry, 1916’ ; O. caucasicum (Sharpilo, 1974) n. comb. [= Neoxysomatium 
caucasicum] et O. dollfusi n. sp. O. dollfusi se distingue des autres espèces par les dimensions et la 
morphologie des spiculés et par la répartition géographique. Toutes les autres espèces classées 
précédemment dans ce genre doivent être assignées à des genres différents. La femelle à’Oxysoma¬ 
tium waltoni Skrjabin, Schikhobalova & Mozgovoi, 1951, est inconnue et cette espèce est laissée 
incertae sedis. Oxysomatium dogieli Skrjabin, 1916, est species dubia. O. tibetanum Baylis, 1927, est 
transféré dans le genre Cosmocercoides et O. baylisi Walton, 1933, est transféré dans le genre Railliet- 
nema. Oxysomatium georgianum Reiber, Byrd & Parker, 1940, est un synonyme de Cosmocercoides 
dukae (Holl). 
Abstract. ■— The genus Neoxysomatium Ballesteros-Mârquez, 1945, is shown to be synonymous 
with Oxysomatium Railliet & Henry, since the type species are the same. Oxysomatium contains 
only the three following species : O. brevicaudatum (Zeder, 1800) [= O. contortum (Linstow, 1906) 
Baylis, 1927 ; = O. longespiculurn Railliet & Henry, 1916] ; O. caucasicum (Sharpilo, 1974) n. comb. 
[= Neoxysomatium caucasicum} ; O. dollfusi n. sp. O. dollfusi differs from the other two species in 
the size and morphology of the spiculés and in geographical distribution. Ail other species pre- 
viously assigned to Oxysomatium belong in other généra. Oxysomatium waltoni Skrjabin, Schikho¬ 
balova & Mozgovoi, 1951, is known only from males and it is left incertae sedis. Oxysomatium 
dogieli Skrjabin, 1916, is designated a species dubia. O. tibetanum Baylis, 1927, is transferred to 
Cosmocercoides and O. baylisi Walton, 1933, is transferred to Raillietnema. Oxysomatium georgia¬ 
num Reiber, Byrd & Parker, 1940, is a synonym of Cosmocercoides dukae (Holl). 
There has been much confusion concerning généra in the Subfamily Cosmocercinae 
(Cosmocercoidea). Cosmocerca, Cosmocercella and Cosmocercoides are easily recognized by 
their distinctive male caudal papillae and Raillietnema by its relatively large eggs which 
are always few in number in the utcri. However, Oxysomatium, Neoxysomatium and Aplec- 
tana are not easily differentiated and numerous different diagnoses hâve been proposed 
by various authors. Important characters hâve not been described in many species. 
A révision of this complex of généra has been undertaken and specimens of numerous 
species hâve been examined. In the présent study the généra Oxysomatium and Neoxyso¬ 
matium are revised ; Aplectana will be similarly treated in a separate publication. 
* Laboratoire de Zoologie (Vers) associé au CNRS, Muséum national d’Histoire naturelle, 43, rue Cuvier, 
75231 Paris Cedex 05. 
Source : MNHN, Paris 
