An unusual preservation of a new species of Cicadomorpha (Auchenorrhyncha) from the Crato formation, Lower Cretaceous of Brazil

Abstract

The Crato Formation boasts an extremely high diversity and abundance of fossil insects with many families preserved in the limestone beds, and several yet unnamed taxa. Here, we present a new insect species found in the Crato Formation limestone associated with branches and leaves of Ruffordia goeppertii, a small creeping plant of Leptosporangiate ferns. The insect is assigned as a member of the Cicadellidae family and is named Hallex martinsnetoi sp. nov. based on morphological description based also on SEM images. The new specimen is articulated and preserved in three-dimensionality, suggesting a relatively fast burial preventing the contact with decomposers or preservation in local anoxic conditions. This fossil shows a rare example of preservation involving Ruffordia goepertii leaves and the Cicadellidae (leafhopper) specimen. The fact that Hallex martinsnetoi sp. nov. was preserved in one leaf, and could be interpreted as some type of insect-plant interaction, but it could also be a taphonomic artefact. The occurrence of Cicadomorpha is consistent with the present interpretation that the limestone of the Crato Formation was formed in lacustrine conditions, and ideal habitat for this group of insects that might be more diverse in this deposit than previously thought.