Overview

Synthemistidae have had a chequered taxonomic history as a separate family or a subfamily of Corduliidae. Since they appear to be sister to the corduliid-libellulid complex they are treated here as a family. Synthemistidae are small to medium sized, rather hairy dragonflies with yellow or bluish markings on a brown to black or sometimes metallic background. The median space is always crossed by at least one vein, and in most genera the forewing has a third thick vein in addition to the usual two primary antenodals. The ovipositor is reduced but the vulvar scale may be long, extending beyond the end of the abdomen in some species.

The family is confined to the South-West Pacific. Australia is home to a majority of the species (26 spp.). The Australian component was recently split into eight genera (Carle 1995; Theischinger 1998) although the differences between certain genera were already rather trivial (Watson et al. 1991). Certain of the genera proposed by Carle (1995) have not been widely accepted (Schorr et al. 2009). There are three main groups: Synthemis and its allies, in which the forewing lacks the third primary antenodal, Eusynthemis and its allies, in which this vein is present, the male appendages are short and the female lacks an ovipositor, and the Tasmanian endemic Synthemiopsis gomphomacromioides , which is recognisable by a brown mark at the base of each wing and a brown spot at the nodus. Synthemistid larvae are bottom-dwellers in swamps and streams, and some withstand desiccation; their wing-sheaths diverge, and the labial palps lack setae on their distal margin.