Unexpected complexity of late Tortonian mangrove ecosystems in the Central Mediterranean: Evidence from the Cessaniti site (southern Italy)

The late Tortonian succession of the Cessaniti site (Capo Vaticano, southern Italy) provides a rare multiproxy-constrained record of Mediterranean coastal ecosystems during a poorly documented interval between ca. 8.1 and 7.2 Ma. Palynological assemblages from lagoonal to estuarine deposits reveal a structurally complex and taxonomically diverse mangrove forest across the central Mediterranean margin, dominated by Bruguiera gymnorrhiza and Rhizophora along with Excoecaria agallocha, Sonneratia, Pelliciera, Casuarina and Hibiscus. In contrast to many Miocene Mediterranean records, Avicennia is absent despite an overall excellent pollen preservation, indicating ecological filtering rather than taphonomic loss. The pollen spectra reveal a sharply zoned coastal-continental mosaic including salt-affected herb communities, freshwater swamps dominated by Taxodium/Glyptostrobus-type, subtropical to warm-temperate forests in the lowlands, and montane belts characterized by high-altitude conifers. Fine-grained, organic-rich substrates and low-energy depositional conditions suggest that local geomorphological stability exerted primary control on mangrove establishment and persistence. The coexistence of floristic elements with African, Asiatic and American affinities, coupled with distinctive late Tortonian mammal palaeobioprovinces, suggests that Cessaniti occupied a biogeographic crossroads within the central Mediterranean. The floristic composition demonstrates that Mediterranean mangroves were not uniformly taxonomically impoverished during the late Miocene. Instead, structurally complex mangrove-wetland systems could persist locally in geomorphologically buffered coastal refugia prior to the late Tortonian–Messinian transition and the Messinian Salinity Crisis. These findings highlight the spatial heterogeneity of Mediterranean mangrove decline and the critical role of local environmental controls in semi-enclosed basins.