A compendium of the genus Helicotylenchus based on 16 diagnostic characters to separate Helicotylenchus species
viz., habitus, body length, ratios a, c, c´, vulva position, DGO from base of stylet knobs, stylet length, shape of stylet
knobs, shape of head, number of head annules, shape of tail, number of tail annules, position of phasmid in relation
to anus, presence of male and female posterior genital branch is presented. These allometric and morphometric
characters were derived from the original descriptions. An up to date list of 230 valid nominal species from world
along with available illustrations and 32 species from Pakistan with diagnostic key is provided.