Silvalis jairajpurii sp.n. with diagonostic compendium and keys to species including one known rare soil nematode (Nematoda: Dorylaimida) from Sundarban region of South 24 Parganas district, West Bengal, India

Silvalis jairajpurii sp. n., a new dorylaimid nematode under the subfamily Thornenematinae is described and illustrated in this study. This is found from rhizospheric soil of paddy in Gosaba block of Sunderban region of South 24 Parganas District of West Bengal, India. The species is characterised by medium sized body (1.5-1.6 mm) with sclerotized cheliorhabdions encircling the strong odontostyle, amphidelphic reproductive system with a very minute vaginal opening terminated by a short blunt, but rounded tail which show marked differences from other species of the genus. This is a plant parasite that affects paddy cultivation and rice in our staple food. So, this type of plant parasite causes economic loss of our country. The species key of this genus with compandium is also provided. Mylodiscus nanus is also rare nematode, reported from paddy field rhizospheric zone of Gosaba block, Sundarbans part of South 24 Parganas, West Bengal of India. It is a predatory nematode.