Insect herbivory on ferns from a midland Atlantic Rainforest locality, southern Brazil: implications for interpreting fossil plant–insect interaction

This work contains the results of fern–arthropod interactions from a midland Atlantic Rainforest locality and addresses the taphonomic, morphological and ecological implications of insect damage on ferns to interpret them on fossil plant assemblages. Six functional feeding groups – margin feeding, hole feeding, surface feeding, piercing and sucking, mining and galling – are present on the three fern species inhabiting the understory of an Araucaria Forest in the Atlantic Forest biome, southern Brazil. We recognised 19 damage types (DTs), including 14 arthropod-induced DTs, three of which are newly proposed herein. Five of the DTs found were first recorded on ferns. Of the DTs found, the proportion of guilds such as mining and galling shows a significant similarity with those of an upland locality. Products of arachnids and insect behaviour on ferns made up 25% of all fern–arthropod interactions in the midland locality, which included dead bodies and byproducts from processes of arthropod life cycle, which are unlikely to be preserved in the fossil record. This rate of arthropod products consists of significant evidence of interactions to unveil deep-time relationships between arthropods and plants. Lastly, leaf damage on living ferns is more frequent than those occurring in fossil plant assemblages.