The genus Hygrophila (Acanthaceae) comprises approximately 100 species with herbaceous habits that are widely distributed in tropical and subtropical regions. Several nomenclatural issues were resolved during this revision of its Brazilian species: lectotypifications for H. conferta , H. helodes , and H. longifolia are designated here, and H. hirsuta is treated as a synonym of H. costata . Our study resulted in the recognition of five species, of which H. paraibana is classified as Endangered (EN), H. costata and H. guianensis as of Least Concern (LC), and H. acutangula and H. nordestina as Data Deficient (DD). We include detailed descriptions of the species, comments on their habitats, reproductive phenologies, geographic distributions, and conservation statuses. Distribution maps, images, and illustrations of the diagnostic characters of each species are also presented.
Monteiro et al. (2026) studied this question.