Species of Pratylenchus Filipjev, 1936 and Helicotylenchus Steiner, 1945 (Nematoda: Tylenchida) Found Associated with Forest Trees in Northern India*

Pratylenchus kumaoensis sp. n. from rhizosphere of Populus species and Helicotylenchus silvaticus sp. n. from the rhizosphere of Quercus incana from Northern India are described and figured. P. kumaoensis sp. n. is characterised by having a relatively smaller spear (14–15 μm), lateral field with four incisures and tail terminus crenated. H. silvaticus sp. n. is distinct in having a high, non-annulated head; relatively smaller spear (19.5–21.5 μm) and longer tail with greater number of tail annules (10–16), and pronounced terminal projection ventrally. Morphological characters and body dimensions are also given for known nominal species viz; Pratylenchus neglectus, P. vulnus, Helicotylenchus indicus and H. pseudorobustus.