Small-sized Megasecopteromorpha (Insecta: Palaeoptera) occurred also in the Pennsylvanian

Pennsylvanian insects were popularised as past giants, but recent discoveries unravelled a yet poorly known component of small-sized forms. A new species of the extinct Megasecopteromorpha, a diverse but unabundant group iconic of late Palaeozoic times, is described from the early Pennsylvanian Xiaheyan locality based on a single individual preserving two wings. While Microhymen inconspicuus gen. et sp. nov. can be confidently assigned to the Bardohymenidae, its very small size, with a ca. 20 mm wingspan, makes it a distinctive member of this family. Its wing morphology is reminiscent of later, distantly related Permian Megasecopteromorpha belonging to the Protohymenidae and Asthenohymenidae. This new record allows highlighting traits likely to be acquired convergently as a consequence of size reduction.

Automated summary

Pennsylvanian insects were once famous for their size, but recent discoveries have shown that there were also small-sized forms. A new species of extinct Megasecopteromorpha has been described from the Pennsylvanian Xiaheyan locality, and it belongs to the Bardohymenidae family. This small-sized species exhibits similar wing morphology to later Permian Megasecopteromorpha species, indicating convergent evolution due to size reduction.