Old collections, new taxa: late Carboniferous (Moscovian) roachoids (stem group Dictyoptera) among plants with insect interactions from the Benxi Formation, China, stored in European museums

The late Carboniferous (Pennsylvanian) witnessed the intensification of climatic gradients with the onset of the Late Paleozoic Ice Age. During this time, high latitudes were characterized by the spread of ice sheets, whereas the palaeotropics hosted the emergence of vast, verdant, coal-forming, swamp forests. Not only were the planet’s landscapes transformed through proliferation and diversification of vascular plants, but the evolution of diverse insect groups, including ‘primitive’ roachoids, reconfigured the terrestrial fauna. Here, we re-examine and describe new roachoid taxa from Moscovian strata of the Benxi Formation. The studied insect material was sourced from early 20th century collections held in the Swedish Museum of Natural History and the Royal Belgian Institute of Natural Sciences, and is co-preserved with a broad array of plant fossils—some with evidence of herbivory damage. Our findings introduce Tangshanblatta inexpectata gen. et sp. nov. (Phyloblattidae), Pseudaphtoromylacris paucinervis gen. et sp. nov. (in the family Pseudaphtoromylacridae, fam. nov.), Spilarchimylacris kaipingense sp. nov. (Archimylacridae), and Etomylacris straeleni sp. nov. and Sooblattella ater sp. nov. (both Mylacridae). We establish Pseudaphtoromylacridae on the basis of several new characters that clearly differentiate it from related families. Etomylacris is restored from synonymy with Mylacris. The co-preserved plant fossils reveal a rich palaeovegetation including pteridophytes, ‘pteridosperms’, sphenophytes, conifers, and arborescent lycophytes. The remains of these plants bear seven distinct damage types belonging to four functional feeding groups: hole feeding, margin feeding, piercing and sucking, and oviposition. This diversity of insects, plants, and herbivory strategies signifies a relatively complex food web in the Carboniferous tropical coal-forming forests of northeast China. This study also demonstrates the value of historical museum collections and the importance of inter-institutional collaboration for piecing together palaeobiodiversity and palaeoecological information from now inaccessible fossil sites.