AbstractAnomochlooideae (Poaceae) represent the earliest-diverging extant lineage of grasses. One of the two genera is the monotypic Anomochloa, which is extremely rare and restricted to the Atlantic Forest of southern Bahia state in Brazil, where only two natural populations have been recorded to date. Knowledge of A. marantoidea is considered crucial to understanding evolutionary and diversification patterns in Poaceae. Despite this, knowledge of the biology and distribution of A. marantoidea remain incomplete, and thus the conservation of this poorly known species is problematic. We used niche modelling to estimate its current distribution and assess potential ranges in situ to explore new occurrences. In addition, genetic diversity and the factors that disrupt gene flow between populations of this species were estimated using molecular markers. Two new populations were documented; the modelled ecological niche indicates high climatic restriction, but also revealed suitable sites for the establishment of new populations. Genetic diversity is correlated to population size, and genetic structure analysis suggests recent fragmentation and low gene flow among the remaining populations, which exhibit high levels of inbreeding. These levels also indicate the capacity of A. marantoidea to respond favourably to selection and, thus, that a conservation plan could be designed to maintain the current genetic diversity.