The neotropical genus H.Karst. is revised. Fifteen species are recognised, including three T.D.Penn., T.D.Penn. and T.D.Penn. which are described as new to science. A key to the species is presented, along with information on the morphology, distribution, ecology, conservation assessments, local names, uses and field characters. All species are mapped and illustrated with line drawings and all specimens seen are cited in a list of exsiccatae.
