Family Siphonolaimidae Filipjev, 1918

Diagnosis (from Fonseca & Bezerra 2014)

Body generally long and slender. Rounded anterior and posterior ends. Cuticle striated. Anterior sensilla variable: 6 + 6 + 4 in the Siphonolaiminae and 0 + 6 + 4 or 0 + 0 + 4 in the Astomonematinae. Amphids circular. One or two gonads may be present. Gubernaculum apophysis oriented dorsocaudally. Tail shortened by histolysis.