An early Permian Euramerican plant assemblage in northwestern Gondwana: The plant-arthropod interactions of the Costela Mine locality, northeastern Brazil

The Costela Mine locality (CM), situated in southern Maranhão State, Brazil, exposes deposits of the Pedra de Fogo Formation (Parnaíba Basin) that preserve an early Permian plant assemblage of notable phytogeographic importance. The assemblage is dominated by callipterid peltasperms, represented by Rhachiphyllum , Auritifolia -like foliage, and Autunia -like reproductive structures. From 525 plant specimens examined, 27 specimens show evidence of plant-arthropod interactions and plant disease. These interactions encompass eight functional feeding groups (FFGs) attributed to arthropod herbivory and one FFG representing plant disease, with a total of 15 distinct damage types (DTs). Among these, Rhachiphyllum sp. hosted the highest frequency and diversity of interactions. For the plant assemblage, the FFG spectrum includes hole feeding, margin feeding, skeletonization, oviposition, piercing and sucking, galling and borings, together with pathogen-induced damage. Such diversity of FFGs suggests an advanced stage of plant–herbivore associations, compared to earlier stages, in the early Permian tropics of Gondwana. Non-metric multidimensional scaling (NMDS) analysis indicate that the CM assemblage is most closely related to the Sanzenbacher Ranch assemblage of Texas, USA, revealing a strong paleoecological tie with Euramerican plant assemblages. In contrast, contemporaneous southwestern Gondwanan floras were dominated by glossopterids that hosted a markedly different FFG spectrum. These findings demonstrate CM represents a key site for understanding the biogeographic links between northwestern Gondwana and southwestern Euramerica, extending the boundary between the Euramerican and Gondwanan Realms southward to present-day central Brazil. This region, corresponding to northwestern Gondwana, currently represents the southernmost and most inland record of the callipterids known from this continent. • The early Permian flora from Costela Mine, Parnaíba Basin, is described as a callipterid-dominated flora. • Herbivory includes eight functional feeding groups from arthropods and one pathogen; a total of 15 damage types. • Rhachiphyllum shows the highest diversity of arthropod–plant interactions. • A NMDS analysis reveals paleoecological affinities with Euramerican floras. • The Costela plant assemblage differs from coeval Gondwanan assemblages dominated by glossopterids.