A few years ago is was discovered that the Australian examples had very different song features from "D. japonica" from elsewhere.
With most katydids the male and female genitalia are species-distinctive. As such they are of primary importance in taxonomy. With the so-called D. japonica, the male genitalia were nearly identical in the tens of specimens studied over its extensive range. However, when the singing characteristics were examined, a different picture began to emerge. Not only were the songs different, but the stridulatory file and features of the wing were very different from one taxon to another. As a result, a number of name changes were necessary. (See Heller et al., 2017 below)
It was soon determined that the Australian katydids were without a name. Ducetia antipoda Rentz and Heller is the new name for this widespread katydid and its common name is the Australian Ducetia. The species was described in the paper below.
Heller, K-G, Ingrisch, S, Liu, C-X, Shi, F, Hemp, C, Warchalowska-Sliwa, E, Rentz, D. 2017. Complex songs and cryptic ethospecies: the case of the Ducetia japonica group (Orthoptera: Tettigonioidea: Phaneropteridae: Phaneropterinae). Zoological Journal of the Linnaean Society, 20: 1-22.
Adult male Ducetia antipoda in typical resting posture.
Alert adult male Ducetia antipoda.
Brown morph male Ducetia antipoda.
Head-on view adult male Ducetia antipoda.
Adult female Ducetia antipoda. This is a common garden inhabitant in the Australian tropics, especially along rainforest margins where there is a mixture of grasses.
Adult female Ducetia antipoda. The spots on the pronotum (thorax) are quite typical of this species.
Adult male Ducetia antipoda showing the claspers (cerci). These are very similar to other species in the genus such as D. japonica and D. malayana.
Ovipositor of female Ducetia antipoda. The serrations are used to aid the female in depositing eggsbetween the layers of the stiff leaves of a plant host.