Mononchus Bastian, 1865

Beside plant parasites, fungal and bacterial feeders some nematodes in the terrestrial and aquatic environment feed on other nematodes. Members of the order Mononchida Jairajpuri, 1969 are typical representatives for this carnivorous behavior although juveniles, with a smaller mouth cavity, also feed on bacteria. The genus Mononchus was described by Bastian in 1865. Since then, many related species have been described resulting in many new genera and ultimately eight families within the order Mononchida.  Mononchids are active nematodes which damage the cuticle of other nematodes and subsequently consume the content. The name Mononchus refers to the single tooth in the mouth cavity. They prefer freshwater habitats and moist soils. The type species Mononchus truncates Bastian, 1865 has a worldwide distribution. Mononchus tunbridgensis was also described by Bastian in 1865. It has a smaller and narrower buccal cavity, compared to M. truncatus, and has been found in Europe, Russia, South-Africa, India, Japan, Austalia, North-America, Suriname and Costa Rica.  

More pictures of Mononchus truncatus:

Mononchus truncatus: female body
Mononchus truncatus: female body

Mononchus truncatus: head region with a large dorsal tooth in a barrel-shaped buccal cavity
Mononchus truncatus: head region with a large dorsal tooth in a barrel-shaped buccal cavity

Mononchus truncatus: buccal cavity with transverse subventral rib
Mononchus truncatus: buccal cavity with transverse subventral rib
Mononchus truncatus: pharynx base, with cardia and intestine
Mononchus truncatus: pharynx base, with cardia and intestine
Mononchus truncatus: vulva, vagina
Mononchus truncatus: vulva, vagina
Mononchus truncatus: anal opening
Mononchus truncatus: anal opening
Mononchus truncatus: tail with terminal spinneret
Mononchus truncatus: tail with terminal spinneret

Mononchus tunbridgensis:

Mononchus tunbridgensis:  Female body
Mononchus tunbridgensis: Female body

Mononchus tunbridgensis: head reagion with dorsal tooth in buccal cavity
Mononchus tunbridgensis: head reagion with dorsal tooth in buccal cavity

Mononchus tunbridgensis: head region in ventral view
Mononchus tunbridgensis: head region in ventral view
Mononchus tunbridgensis: pharynx base with cardia and intestine
Mononchus tunbridgensis: pharynx base with cardia and intestine
Mononchus tunbridgensis: vulva
Mononchus tunbridgensis: vulva
Mononchus tunbridgensis: anal opening
Mononchus tunbridgensis: anal opening
Mononchus tunbridgensis: anal opening
Mononchus tunbridgensis: anal opening

Mononchus tunbridgensis: posterior tail region
Mononchus tunbridgensis: posterior tail region

(Click on the pictures for an enlargement, © Wageningen University & Research, Laboratory of Nematology/Pictures: Hanny van Megen)