Macroscale morphological features of Jurassic European coleorrhynchans (Hemiptera)

During the Jurassic period, the Hemiptera were a diverse, abundant, and adaptable group of insects. This period saw the diversification of numerous lineages, which continue to exist as crown groups in the present day.

The Jurassic European entomofauna represents one of the most significant Mesozoic faunas. The fossil sites in Germany, Switzerland, Luxembourg, Belgium, and England contain fossils of insects (and other organisms) that originated from the surrounding mainland areas or offshore islands. The degree of preservation varies considerably. In the majority of cases, only isolated wings are present, although in a few localities, complete specimens have been recovered.

The Coleorrhyncha (Hemiptera) are characterised by their minute size, yet they yield a wealth of data. It is an excellent model group, demonstrating the morphological response to changing environments and the direction of Hemiptera evolution. The collection includes specimens that are exceptionally well preserved, as well as those that are severely damaged or of questionable taxonomic value. The majority of diagnoses are based on straightforward characteristics of the forewings, including their individual states and combinations thereof. It is therefore evident that a more detailed recognition and understanding of the features in question is crucial for their study.

The rapid fossilisation process allows for the observation of well-preserved specimens with fine details. We took advantage of this fact through examination with SEM and EDS and morphometric analysis. Over 150 fossils were subjected to analysis. Scanning electron microscopy (SEM) and EDS (Energy-Dispersive Spectroscopy) were employed for macro-scale investigations of colour remnants of cuticles, spinulations, and other previously unidentified minutiae within Coleorrhyncha. The findings of this study revealed novel microfeatures of the pronotum, mesonotum, head, and genital plates. Macrosculptural patterns exhibited variation between the taxa, rendering them useful for taxonomic purposes.