Helechos y licofitas del sudeste del Sistema de Tandilia (Buenos Aires, Argentina): composición, afinidad biogeográfica y patrones de diversidad ecológica

Background and aims: The Tandilia system is a fundamental refuge for a highly diverse biota throughout the wide climatic variability of the mid-late Cenozoic that affected the Pampean steppe, especially for fern and lycophyte flora. The geology and proximity to the sea in the southeast of the Tandilia system raise questions about the composition and biogeographical affinities of the fern and lycophyte flora. Furthermore, given the anthropogenic landscape transformation, it is necessary to inventory the status of the frequency and microenvironments in which these species develop. Thus, we present an inventory and frequency of ferns and lycophytes of the southeast of Tandilia associated with different microenvironments and biogeographical affinity and develop a dichotomous key for the area. M&M: We collected fern and lycophyte between 2006 and 2024 in Balcarce and General Pueyrredon hill ranges and they were compared with those fern and lycophyte flora from Ventania and Tandilia. Results: This study shows that 51% of the ferns and licophytes reported at Tandilia rangeland System develope in the southeastern of Tandilia. An increase of AustroBrazilian elements and decrease of Austral-Antarctic elements were observed, linked to latitudinal and biogeographical aspects. Adaptive traits related to a water availability gradient and different microenvironments were established. Eight species were cataloged as rare due to their low frequency. Conclusions: The results highlight the need to plan conservation areas for the fern and lycophyte flora of the Tandilia mountain system.