A new species, Trirammatus torqueotrochantus is described from Caram vida, Chile. Males of this species are distinguished by unique femur-length, twisted and falcate trochanters, which are a form unlike that of any described pterostichine. Both sexes are recognizable from other species of Trirammatus by the combination of short metepisternum and bicolored legs. The species is included in Trirammatus based on the shared condition of having paired sub-tarsal claw setae. The status and characters of genera thought to be near relatives of Trirammatus, the evolution of elongate metatrochanters and their relationship to wedge-pushing are briefly discussed. The hind legs of T. torqueotrochantus, Pterostichus (Cylindrocharis) acutipes acutipes, P. (Steropus) moestus and Acanthoferonia ferox are illustrated to show relative trochanter lengths.