Caryboca paranaensis n.g., n.sp. (Nemata, Actinolaimidae) was found inhabiting soil around coffee roots sent in from Cornélio Procópio, State of Paraná, Brazil. Definition of the new genus: Actinolaimidae, Actinolaiminae. Lip region distinctly offset by a constriction and showing a cuticularized basket-like structure provided with lateral denticles and two rather strong teeth pointing forwards. Cuticular rod-like thickenings extending back from the basket-like structure to the guiding-ring. Anterior part of oesophagus a non-muscular, narrow tube; posterior part wider and provided with strongly developed radial musculature. Gonads paired and reflexed. Tail attenuated, pointed. Males and food habits unknown. Caryboca n.g. differs from Actinolaimus Cobb, 1913, by having a labial basket-like structure as well as by the non-muscular nature of the anterior part of oesophagus. Caryboca n.g. differs from Carcharolaimus Thome, 1939, by having two strong pharingeal teeth and pointed tail.