Abstract (Hypolytrum (Cyperaceae): taxonomic and nomenclatural notes, geographical distribution and conservation status of Neotropical species.) Hypolytrum (Mapanioideae) is a medium-size and Pantropical genus of Cyperaceae, closely related to Mapania, Principina, and Scirpodendron. In the Neotropics, it is found from southern Mexico to southern Brazil where it grows in the Atlantic and Amazon Forests and Cerrado vegetation. Most of the species are found in the humid and shady understory of forested habitats. Twenty-nine species are confirmed, nine of which are considered narrow-endemics and one is poorly known. Twelve species are classified under the conservation status of Critically Endangered or Vulnerable. A total of 130 types (holo- types, isotypes, lectotypes and isolectotypes) and 42 photos of types were checked and confirmed, and 22 synonyms were verified and accepted. Information about geographic distribution including new occurrences, habitat and diagnostic characters are also provided.