22 March 2012

Western Flag-face - Propsednura eyrei

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Western Flag-face - Propsednura eyrei

These unusual grasshoppers belong to the Pyrgomorphidae family, which also includes the very similar Psedna nana, the Variable Psedna (details). Although the colours vary between these species, this is not a good method of identification, as the Variable Psedna is as its name suggests highly variable, including juveniles taking on different coloration to that of the adults. I have caught a number of these Variable Psedna grasshoppers and can only establish identity by examining the appendage in the neck region (paraglossae), which is short, broad and triangular with Psedna nana, but long and peglike with the Western Flag-face, Propsednura eyrei.

Besides the adult breeding male above, I also have photos of what I think is the female, but alas, I did not examine the paraglossae, so cannot be sure of identification and hence it has been excluded. These two grasshopper species (which are of similar size) live on round-leaved sedges and being wingless, hop from one plant to another, providing they are within a metre (4’) or so of each other. This limited method of traversing their habitat may be the reason why locally this species is far less common than the Variable Psedna.

The Variable Psedna is very common in low-lying areas where round-leaved sedges can cover several hectares/acres. This species (Propsednura eyrei) on the other hand seems to prefer the more elevated and better drained heath areas, where this type of sedge although common and widespread, are more spaced and often surrounded by bushy shrubs that would hinder the movement of these insects. It may be that this species needs frequent bushfires to reduce the number of heathland shrubs, but encourage the growth of sedges and other suitable vegetation. A couple of habitat shots of mature heath vegetation are included, which may no longer be suitable Propsednura eyrei habitat.

Further reading: A Guide to Australian Grasshoppers and Locusts by Rentz, Lewis, Su and Upton.