A new species of Proshapalopus Mello-Leit~ao, 1923, distributed in the Southwest Colombia in the Choc
o Region, is described. A morphological cladistic analysis based on the previous matrix of a Theraphosinae group confirmed the inclusion of this species within Proshapalopus. The new species, Proshapalopus marimbai n. sp., can be distinguished from other species of the genus mainly by the reduced number of labial cuspules, around 40; in contrast the other species having over 100. Males can be distinguished by the thickened femur III, presence of intermediate urticating setae type I-III only, palpal bulb with a considerably long prolateral inferior keel (from ventral median depression to embolus apex) and the accessory keel pronounced distally. Females can be distinguished for lacking urticating setae type III and the non-incrassated tibia IV. This discovery constitutes the fourth species described for Proshapalopus and the first record for Colombia, expanding the geographical distribution of the genus, until now known for Brazil only. Other aspects of distribution and the phylogenetic relationship of the new species are also discussed here.