Taxonomic Updates of Thismia pseudomelanomitra (Thismiaceae) Reveal an Old Acquaintance From the Ecuadorian Amazon

ABSTRACT The Amazon Basin is home to the world's greatest terrestrial biodiversity, but many plant groups remain poorly studied. One example is the mycoheterotrophic genus Thismia (Thismiaceae), which is notable for its highly specialized floral morphology and ephemeral life cycles, making it difficult to detect in the field and limiting its representation in scientific collections. Here, we report the first confirmed record of Thismia pseudomelanomitra in the Ecuadorian Amazon and expand its known distribution to the Brazilian State of Acre. Our study is based on a comprehensive review of herbarium specimens (AAU, RB, UFACPZ) and photographic records from iNaturalist.org . We also provide the first morphological description of its fruits and seeds, a distribution map, and an identification key for Ecuadorian species. Morphological comparisons reveal significant differences from related taxa, particularly T. melanomitra and specimens previously assigned to T. singeri . These findings highlight the role of citizen science and integrative approaches in documenting rare taxa and advancing conservation strategies.