Family Xyalidae Chitwood, 1951

Diagnosis (from Fonseca & Bezerra 2014)

Cuticle striated. Six outer labial setae and four cephalic setae in one circle, with cephalic setae shorter than or at most equal to labial ones. Often additional cephalic setae and occasionally eight groups of sub-cephalic setae are present. Stoma usually funnel-shaped, completely, or only at the base surrounded by pharyngeal tissue. Ventral gland mostly absent (or invisible under light microscopy). Females with one (anterior) ovary to the left side of intestine. Males usually with two testes, the anterior one to the left side of intestine, the posterior one (may be absent) to the right side.