Plant–insect interactions in the Quaternary fossil record of the Azores Archipelago (Portugal)

The fossil record of the Azores still lacks evidence of terrestrial invertebrates. Based on a study of the collections of Quaternary fossil plant imprints from the Azores, located in the depositories of public collections and also newly conducted field research, several samples of fossil leaves with traces of plant–animal interactions were found. These are evidence of marginal feeding (Phagophytichnus ekowskii) and anophionome mine (Cuniculonomus isp.). One specimen with traces of boring in fossil wood (Xylonichnus trypetus), previously only briefly mentioned in the literature, was also described in detail. In addition to a detailed description of the found traces, the present study also discusses the possible trace-makers, using a comparison with the recent phytophagous fauna in relation to the original vegetation of the Azores (that includes laurisilva forest). It is thus possible to consider butterfly caterpillars (group Macrolepidoptera) or locust larvae (Orthoptera/Caelifera) as possible originators of marginal feeding. The ophionome mine could have been caused by the larvae of leaf-miner flies (Agromyzidae) or moths from the group Microlepidoptera (Gracillariidae). Wood-destroying beetles could be the cause of the boring in fossil wood.