27 December 2009

Acanthomima rhipheus – Spiny-thorax Stick Insect

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Spiny-thorax Stick Insect - Acanthomima rhipheus

Stick Insects belong to the Order Phasmida and are commonly referred to as phasmids. The Family Phasmatidae contains around 100 species within Australia, most in the northern tropical regions. Upon reading up on these insects, it is easy to get the impression that much is still to be done regarding classification and distribution, however I largely made do with “The Complete Field Guide to Stick and Leaf Insects of Australia” by Paul D Brock and W Hasenpusch. As only a handful of phasmids were listed for the Esperance region, I thought identification would be easy, but I am quickly coming to the conclusion that there may be other species here and all are surprisingly difficult to identify, despite the informative keys and descriptions.

Acanthomima rhipheus with its spines looked highly distinctive and easy to pin-point, but after examining the local species none seemed to fit, but eventually I did locate it, but it was listed to the north and south of Perth and a long way from Esperance. On probing deeper, the west coastal distribution had since been extended much further east, although still a considerable distance from Esperance, but a few collections have been made in South Australia, so it was not unreasonable that it should also occur here.

In the photos bove there are only females, which are recorded growing to 72 mm in body length, although I am sure mine were a little larger. The males have longer antennae, but are apparently shorter in body length to around 50 mm. There are other local Stick Insects with spines or tubercles on the thorax, but not as pronounced, plus they do not have the strong serrations and spines on the legs. Nor the presence of rudimentary wings on the female (male has none), the white body mottling, or the very short cerci (appendages at the end of the abdomen).

Spiny-thorax Stick Insects are not uncommon in the Esperance white sandy Banksia heathland, but in its wider distribution, is obviously found in other habitats too. Most of my photographs were taken during November and December.