Gynacantha dobsoni is a species of dragonfly in the family Aeshnidae, known as the lesser duskhawker. It inhabits ponds and swamps and is found in northern Australia.

Gynacantha dobsoni is a large dull-coloured dragonfly with a constricted waist in its abdomen at segment 3. It is smaller than Gynacantha rosenbergi, which in many ways appears quite similar. From 35 specimens of Gynacantha dobsoni held in the Australian National Insect Collection at the CSIRO, an average wingspan of 109mm and overall length (including appendages) of 78mm has been determined. It is a crepuscular insect and flies at dawn and dusk.

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