Lips fused, triangular, with 6 labial papillae. Basal bulb of esophagus swollen, with vestigial valve. Nerve ring located anterior to basal bulb or arround isthmus. Excretory pore anterior to basal bulb, anterior to nerve ring in most of first generation adults and all second generation adults. Vulva a transverse slit, near mid-body, located on a protuberence.
Eggs usually develop and hatch in reproductory system.
Tail rounded without projection. Tail of the second generation conoid usually with a small papillae, 1-5 um long. Gonad monorchic, reflexed. Posterior region with 23 genital papillae. Spicule head narrowing posteriorly to form a distinct shaft.