More than a century later: first modern record of Pteroglossa macrantha (Orchidaceae: Spiranthinae) in Argentina, with notes on its morphology, distribution, habitat, and conservation implications
DOI:
https://doi.org/10.15517/jnh7g404Keywords:
Corrientes Province, Paraná River, riparian grasslands, southern distribution limitAbstract
Abstract. Pteroglossa macrantha (Orchidaceae: Spiranthinae) was previously known in Argentina only from a historical collection made by Ekman in 1908 in the province of Misiones, with no subsequent records confirming its presence in the country. During recent botanical surveys in the province of Corrientes, a new population was discovered, representing the first modern record for Argentina after more than a century and one of the southernmost confirmed occurrences of the species in the country. Detailed morphological observations confirmed its identity and revealed slight variations in leaf proportions compared with specimens from Brazil and Paraguay. The plants of this species grow in seasonally flooded alluvial grasslands on sandy substrates near the Paraná River. The regional conservation assessment, based on IUCN criteria, indicates that P. macrantha should be considered Critically Endangered (CR) in Argentina due to its extremely small area of occupancy, its occurrence in a single locality, and ongoing habitat degradation. This finding highlights the importance of the riparian grasslands of Corrientes as biodiversity refuges and priority areas for the conservation of rare and threatened orchids of the Southern Cone.
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