Christmas Bells

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Christmas Bells - Blandfordia nobilis

Monday, March 05, 2012

Barking up the Wrong Tree?

I went bush with Bob Mesibov, a Millipede expert from Tasmania, yesterday. Bob visited Robertson 3 years ago, in search of another "long-lost Millipede"

This visit, we went down to Barrengarry Nature Reserve, initially, to have a quick look, because Bob was chasing a particular Millipede which had originally been recorded from "Barrengarry". That name could refer to anywhere between Robertson (where the Barrengarry Creek rises), to Kangaroo Valley (where it drops into the lower level of the Valley); or if one goes by the road names, anywhere from Fitzroy Falls road down to Kangaroo Valley. So I opted to show Bob around the various bits of the "Barrengarry area", and let him tell me which areas were most likely to suit his Millipede friends.

Then, seeing as he was here, all the way from Tasmania, I wanted to show him a few other places which, because they were such good areas of wet forest, might also suit other Millipedes. So after we had scouted out a few likely locations within the general Barrengarry area, we went to Leebold Hill Road, on Cambewarra Mountain.

We got wet, wet, wet. 

Bob found a fair number of Millipedes - "wild, native Millipedes" not the annoying feral ones. Many of these are tiny things living in the guts of old fallen trees - rotting logs on the ground. They play an important part in breaking down the vegetation.

Some of these things, Bob explained to me, like to live under leaf litter, and during the day, they will hide under rolls of shed Eucalypt bark, or even under bark on a fallen trunk or branch.

In fact it was so wet, on top of Cambewarra Mountain, that he discovered the best locations were off the ground, on a dead or dying tree. As the tree dies, the bark separates from the stem or trunk, creating hidey-holes for Millipedes.

While we were searching likely spots, I came across these "critters", hiding out under the bark of a branch of a Blackwood Wattle (Acacia melanoxylon).

It was dark, under the heavy tree canopy, and my glasses were not functioning, as they were covered in steam and drops of water. So I could not see very well when I lifted back a piece of loose bark.
I saw movement,  a kind of horizontal shuffling movement. I assume they were Spiders, but they turned out to be a flat kind of Cricket - clearly designed to live under the limited spaces between loose bark and the tree trunk - just where they were.

I gently lowered the bark back where it was, and went to get the Camera out of the car (as it had been way too wet for me to carry the camera about all day). Ten minutes later, Bob lifted the bark for me, and I fired off a few shots, and this is what was going on in under that loose sheet of bark.

The male (on the right) has really long, fine antennae.
In the original image, I can just make out that
the antennae of the male reaches up to 
beyond the tail of the female.
It must be about three times the length of his body.

Click these images to enlarge them, 
to see the insects in full detail
Female "Bark Cricket", left (Tathra oligoneura)
in middle is a "Bark Cockroach" Laxta sp
on right is a male Bark Cricket (with small wings).
 Click these images to enlarge them, 
to see the insects in full detail.
Head of the female Bark Cricket (Tathra oligoneura)

Strange creatures. Brown, and mottled. 
The female has a really long ovipositor (its egg-laying tube).
The tip of the antenna of the male (out of picture, to the right)
can be seen bent across the tail of the female,
behind her back leg.
Amazing, because he is out of frame, yet his antennae is
clearly visible.
Relative to his body length his Antennae are really long.

 Click these images to enlarge them, 
to see the insects in full detail
Rear end of female Bark Cricket (Tathra oligoneura)
note the long, spiny "ovipositor" in middle
between the two wide-spread "cerci"
She has lost a leg, something which had occurred naturally.
The male has two half-formed wings*** (see comment below). 
There's clearly not a lot of flying going on where they live, under the bark.
Click these images to enlarge them,
 to see the insects in full detail
Looking at the male Bark Cricket (on the right)
Tathra oligoneura - note the very long antennae
and the flattened body.
Distinctive blotched appearance on legs.

Strangely (to my eyes) the male has really long antennae. 
About three times as long as its body. 

There is an E-Book "Australian Crickets"
by Otte and Alexander.
On P. 255 it lists Tathra oligoneura, as being recorded 
in central coast and northern NSW
 and notes it as a "Wet Forest" Cricket.

Dave Rentz has subsequently confirmed my ID of this Cricket
and has told me that in his experience 
it is "common at Bawley Point"
that is south, between Nowra and Batemans Bay.
So my Crickets were "in range". Good news.


Post Script:Cricket chasing by torch light.
Tonight I went into the 
Robertson Nature Reserve with Bob Mesibov
looking for various arthropods which he assured me 
"would be out and about after dark"
How right he was.

We found lots of Millipedes, 
and some of this same species of Cricket.

Much to my amazement,
the male Crickets use their wings for display purposes.
*** (Referring back to comment above)
They hold them upright in the middle of their backs,
It totally changes their appearance and profile.
They no longer look "flat" when their back is
made to stand out by having two cross-ways flaps extended
which is the effect when the wings are held vertically.
They look quite impressive, really, even to my eyes.

We also found some Flat Worms and a number of Semi-Slugs
(which I have seen and photographed before).
They are lichen and fungi eaters 
so they cruise around at night on the
trunks of trees, devouring any moss or lichen growth 
and on occasions they will browse on some fungi.
They are really snails with a reduced shell
like a casually dressed Frenchman might wear his beret, 
on a slight angle.

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