Hidden herbarium treasures: Eugenia carinata (Myrtaceae), a new species described twenty-five years after collection

After a detailed revision of herbaria collections from São Paulo state, a new species of Eugenia is described based on herbarium specimens collected in 2000. Eugenia carinata is known from only two collections from Parque Estadual da Serra do Mar—Núcleo Caraguatatuba, in the northeastern region of São Paulo state, Brazil. The new species is remarkable for its strongly protruding ridges on the hypanthium which is covered by a dense yellowish to ferrugineous indumentum. It is most similar to Eugenia sulcatifolia, from which can be distinguished by its narrower leaf blades with midvein prominent adaxially, deciduous bracteoles, costate hypanthium and longer calyx lobes. This study highlights the importance of herbarium collections as repositories of undocumented biodiversity, preserving records of species that may remain unknown for decades after collection. Despite the type location is within a highly collected spot in the Atlantic Forest, E. carinata has not been recollected since 2000, emphasizing both the value of herbarium-based taxonomic research and the continued need for investment in taxonomic expertise and biological collections.