Integrative floristic and DNA barcode assessment of true mangrove species in the Maldives

Mangroves are critical coastal ecosystems, yet their floristic composition in the Maldives has long been obscured by taxonomic uncertainty. We conducted the first integrative assessment of Maldivian mangroves, combining morphology, DNA barcoding, and a country-specific diagnostic key. Surveys from 2022–2024 confirmed 12 true mangrove species representing six families and eight genera. Morphological traits provided consistent diagnostics, while matK and rbcL barcodes (≥ 99% BLAST identity) corroborated species identifications and resolved higher-level relationships, although resolution was limited among closely related taxa such as Bruguiera. A concatenated Maximum Likelihood phylogeny recovered expected family-level clades, with shallow intrafamilial divergence in Rhizophoraceae (e.g., Rhizophora mucronata–R. apiculata d = 0.0034) and deep interfamily separations (e.g., Avicennia marina vs. others d ≈ 0.18–0.26). Three additional taxa, Pemphis acidula, Acrostichum aureum, and Derris trifoliata are treated here as associates rather than true mangroves. By linking voucher specimens to DNA barcodes, this study establishes the first verified checklist and identification key for the Maldives, providing a robust baseline for monitoring, restoration, and conservation planning.