Female body usually in a tight spiral. Lip region set off by slight depression with 4 or 5 minute annules which sometimes are scarcely visible. Spear 27u long with massive angular, slightly cupped knobs. Cephalids usually easily seen. Dorsal gland outlet about 8u posterior to spear. Excretory pore slightly posterior to junction of esophagus and intestine.  Hemizonid two annules anterior to pore.  Ovaries outstretched and prominent spermathecae.  Oocytes in single file except for a region of multiplication. Tail with 10-12 annules, ending in a hemispheroid process. Six tiny annules on dorsal side which extend up to end of lateral field. Phasmid usually slightly anterior to anus.
Male not so completely spiral. Spicula 30u-33u long, almost straight, decidedly longer than tail length- an outstanding feature. Gubernaculum cephalated, more massive than usual, about 12u long.  Phasmids 6-8 annules anterior to anus.

Helicotylenchus hydrophilus is easily recognized by the finely annulated lip region, position of excretory pore, terminus of female tail and length of spicula.

Habitat:  Bank of slough 2 miles west of Brookings, South Dakota.
(Description- Thorne and Malek,1968)