A new passalid fossil (Insecta: Coleoptera) from the Santana Formation (Crato member, Lower Cretaceous), Araripe Basin, NE Brazil: Paleoecological and paleobiogeographic implications

Abstract

Species with a xylobiont lifestyle (e.g., inside fallen tree trunks) are rarely fossilized because of their taphonomic peculiarities. Reconstructing the evolutionary history of these lineages is challenging, especially with respect to dating major events. Here, a new genus and species of Passalidae, Protopassalus araripensis gen. et sp. nov., is described based on a well-preserved fossil in laminated limestone from the Crato Formation (Santana Group, Lower Cretaceous, upper Aptian), collected in a quarry near Nova Olinda, Chapada do Araripe, State of Ceará, Brazil. This specimen is the oldest passalid fossil and the first record for the family in the Santana Group, and aids in understanding the origin and radiation of terrestrial Coleoptera. Protopassalus araripensis gen. et sp. nov. shows characteristics of the subfamily Passalinae, representing the oldest record of this group and suggesting that the family emerged over 150 Ma. The new genus is attributed to this subfamily based on: outline of head and eyes with strongly convex frontal area, posteriorly grooved and curve, with incomplete central tubercle; pronotum rounded at sides with longitudinal groove; mesothorax with narrowing connection with abdomen, dorsally evident; elytra longitudinally striated and with similar dorsal striae and interstriae. We propose a new sequence of events in the Passalidae paleobiogeography, as a basis to evaluate other organisms of low dispersal ability.