A new species of Hapalotremus Simon, 1903 from northern Argentina is described and illustrated. Hapalotremus martinorum sp. nov. differs from all other congeners by the colour pattern of live specimens. Males differ in the male palpal bulb morphology, with thickened and less curved embolus having a blunt subapical keel and less-developed apical keel. Females differ in the shape of the spermathecae, with the lateral bases more pronounced than the superiors and the upper edge more rounded. Specimens were captured inhabiting short burrows or crevices under stones in high cloud forests.

New specimens of the genus Hapalotremus (Theraphosinae) are revised based on the examination of types and additional material collected in Argentina, Bolivia and Peru. A new generic diagnosis is proposed. New information and illustrations are provided for known species and seven new species were recognized and are newly described and illustrated. Hence, Hapalotremus comprises 10 valid species, distributed along the Andes and Yungas in western South America. All species are keyed and mapped. New taxonomic features are included in the descriptions and the detail of embolus keels morphology and positions are described for the first time for the genus. Information on species habitat is included. The highest altitude record for a Theraphosidae spider, living at 4524 m above sea level, is reported.