01 January 2010

Phasmodes ranatriformis - Zaprochilinae - Tettigoniidae

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Phasmodes ranatriformis - Zaprochilinae - Tettigoniidae

Despite looking like a Stick Insect, Phasmodes ranatriformis is actually a Katydid, but this was not my first impression and my photographs were casually filed under the former classification. It was not until recently when sorting through the phasmids (Stick Insects) that I began to get second thoughts. What I had considered to be the tail end of an elongated body, was really a straight ovipositor (used for laying eggs), also the head was different and could easily bend forward, plus the antennae were too long for local stick insects. So I sent a few photos to Dr David Rentz who confirmed my suspicions and kindly identified them as Phasmodes ranatriformis.

These katydids are around 10 cm in length (head/body/ovipositor) excluding antennae and legs, so are similar in size and appearance to many stick insects, plus they behave like one by slow deliberate movements. This unusual group of katydids include the much smaller Kawanaphila species http://esperancewildlife.blogspot.com/2009/07/kawanaphila-species-zaprochilinae.html and the winged Windbalea viride http://esperancewildlife.blogspot.com/2009/07/green-westwind-katydid-windbalea-viride.html, which are largely restricted to the southern regions of Western Australia and characterised by the mouth-parts, designed to feed on flowers, pollen and nectar.

A number of individual Phasmodes ranatriformis have been photographed and all during November and December, which may just reflect the blossom they feed on at this time of year. However being wingless they must reside permanently in the white sand, coastal, Banksia heath, but are less noticeable at other times. The plants on which they were found, include the Kangaroo Paw, Anigozanthos rufus, but more commonly the long flowering Chittick, Lambertia inermis (both detailed in my Esperance Wildflowers Blog).

Another feature of this particular katydid is their body color, which is either green or brown, but is not dependent on gender. However with other species, color variation may be related to the time of year, green being dominant during spring and early summer, and brown during the dry summer/autumn period. This may result in better camouflage, plus determine available nutrition, but whatever the reason, color differences are not uncommon amongst Katydids.