Family Monhysteridae de Man, 1876

Diagnosis (modified from Fonseca & Decraemer 2008)

Small, slender nematodes usually less than 2.5 mm long. Cuticle smooth or striated. Anterior sensillae in two circles: anterior circle with six inner labial sensillae (usually papilliform) and posterior circle with six outer labial sensillae and four cephalic sensillae (both usually setiform). Amphideal fovea circular or cryptocircular. Buccal cavity small to medium-sized, bipartite or single, with or without denticles. Pharynx with or without posterior bulb. Secretory-excretory system present or absent. Female reproductive system monodelphic with outstretched gonad to the right of intestine; male monorchic with anterior testis to the right of intestine (except Monhystrella kermadecensis sp. nov. where position of anterior gonad relative to intestine is variable). Spicules usually simple and arcuate. Tail conical to conico-cylindrical; terminal setae absent.