In the Netherlands, the genus Tylencholaimus de Man, 1876 is represented by eight species. These are relatively small nematodes, ranging in length from 0.3 to 1.2 mm. Tylencholaimus can easily be recognized by the offset lip region and the weak, thin odontostyle, with a broadening at its basis, the odontophore. This broadening, with basal knobs, serves to adhere the muscles which protrude the odontostyle.
In general Tylencholaimus species live in sandy soil although they also occur in aquatic habitats. They are distributed all over the world. Tylencholaimus can be easily cultivated on fungi and we assume, that in the soil, their main diet is fungal material. Tylencholaimus and relatives are sensitive to pollutants, their presence in the soil is a good sign.