Phenotypic variability in Hemiphlebia mirabilis (Odonata: Hemiphlebiidae): insights into the origin of the discoidal cell in odonates

This paper reports on the studies of two populations of the locally distributed damselfly Hemiphlebia mirabilis Selys in south‐eastern Australia to determine the length of the maturation period, describe age‐related changes in colouration, and quantify phenotypic variability in body size and wing venation. Modern odonates have a closed discoidal cell, which likely increases flight efficiency, but H. mirabilis was thought to always have an open discoidal cell in the fore wings. The study of 82 specimens documents variability in the discoidal cell character of wings as open or closed, with a minority of specimens showing all four discoidal cells closed, and others having one hind wing cell also open. Males are larger than females and body size decreases over the short flight season. Recapture histories of marked animals suggest that males emerge earlier than females and that sexual maturation takes 4–5 days. They become progressively darker, from metallic green to bronze, and their wings less flexible with age. The colour of pterostigma is sexually dimorphic. Male paraprocts and female anal valves are bright white, but in some specimens show a sky bluish tint when observed in direct daylight. Given that recent molecular studies suggest that H. mirabilis has evolved from an ancestral lineage, body colouration and wing venation may be plesiomorphic characters for this taxon.