Halicephalobus
Halicephalobus is a genus of nematodes belonging to the family Panagrolaimidae. The genus has almost cosmopolitan distribution. Species:

Halicephalobus gingivalis 
Halicephalobus intermedius 
Halicephalobus laticauda 
Halicephalobus limuli 
Halicephalobus persicus 
Halicephalobus mephisto

References

Nematodes