Protomiamia yangi gen. et sp. nov. (Early Pennsylvanian; Xiaheyan, China), a sexually dimorphic Palaeozoic stem-Orthoptera
Abstract
The Xiaheyan locality in China is delivering an unprecedented corpus of data on Early Pennsylvanian insects. In this paper
we describe a new species of stem-Orthoptera recovered from this locality, Protomiamia yangi gen. et sp. nov., for which
the available sample allowed us to identify both male and female individuals based on distinctive terminalia on one hand,
and a shared wing coloration pattern on the other. Other dimorphic aspects include body size, with that of the male being
about two-thirds that of the female. Among extant polyneopteran insects such dimorphism is associated with the ‘maleabove-
female’ copulation position (more exactly, ‘male-above-female-with-his-abdomen-twisted’), which we infer as the
putatively plesiomorphic condition for crown-Orthoptera. The delimitation of ancient stem-Orthoptera species will have to
take into account the possible occurrence of such sexual size dimorphism.