Overview

The tiny, metallic green damselfly Hemiphlebia mirabilis is the sole species in superfamily Hemiphleboidea. It is endemic to south eastern Australia, being known from a half-dozen sites in Victoria, on King Island, and in north east Tasmania. The habitat is coastal or lowland swamps. Several of the known sites are degraded or have been much affected by drought in recent years. Hemiphlebia is protected in Victoria and is listed in the IUCN Red data list (http://www.iucnredlist.org/) as an endangered species.

Hemiphlebia can be recognised by its very small size (wing 11 mm, abdomen 20 mm), uniform green metallic colour, and white caudal appendages which are longer in the male but prominent in both sexes, and are displayed by the insect each time it settles. Whether this display is a signal or merely a consequence of the abdomen being brought forward and up, as if to smooth or clean the wings, is not known. The venation is remarkable in that the crossvein at the arculus is missing in the forewings, leaving the discoidal cell open at its base. This is a derived character state, probably associated with the reduction in size, not a primitive state as once was thought, as evidenced by one specimen in the Australian Museum collection having the forewing discoidal cell closed on one side. Ancientness is a relative term, and Hemiphlebia has long been regarded as a 'primitive' or relict odonate, but it is probably a member of the Lestoidea group of families, most likely sister to a clade comprising Lestidae plus Synlestidae , having departed from the common ancestor of all Lestoidea in the early Cretaceous or late Jurassic.