Hemicordulia tau

Tau Emerald



Observer

Tags / Aspects

Description

This dragonfly is perched on a Leafless wattle, Acacia aphylla, growing in the garden.

Date & Time

  2015-02-17 04:44 PM

Location

-38.082021 , 147.086052 : 12.586 m

Near Cobains VIC 3851, Australia

Discussion

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  1. Suzanne Jones  Thanks Russell. Just a question though. I thought that the pterostigma of Hemicordulia australiae was black, while the pterostigma of Hemicordulia tau was brown. Is this not correct? That was why I thought it was H. tau.

    Reply • 18 Feb 2015

    • Russell Best  You are spot on Suzanne. I was in a rush (doctors waiting room) and I didn't even look at the pterostigma. I first look at the abdomen shape for these two species and made my decision solely based on the shapely abdomen and thin 'waist', which points to H. aus. and not H. tau. But you are spot on in that pterostigma colour is an excellent distinguishing feature and in this case points clearly to H. tau. After your comment I looked at the other differenting features and half point to H. aus.. These features are yellow spot on tail in H. tau is absent, curvy abdomen with thin 'waist' for H. aus. is there, yellow veins on leading edge of wings for H. tau are there, brown pterostigma points to H. tau. I've had a look on the web and I can find no deviation from the black pterostigma in H. aus. so I will follow it up further. It is a very interesting case!

      Reply • 19 Feb 2015

      • Russell Best  I meant to conclude that the distinguishing features score is 2:2 between the two species!

        Reply • 19 Feb 2015

        • Suzanne Jones  I wondered if maybe it was my photo and that the wings were making it just look as if it had a thin waist, so have added another photo of the dorsal view, taken from a very slightly different angle. Don't know if it will help or not. The wings are a bit blurry in all my photos because the insect was moving them constantly.

          Reply • 19 Feb 2015




NS Observation No. 54E3DD46ED2A89D9900003C3
Created 2015-02-18 11:31 AM (over 4 years ago)
Created By Suzanne Jones
Updated 2015-02-21 03:06 PM (over 4 years ago)
Updated By Suzanne Jones
Edits 4
Photo Quality
Camera Date-Stamp Yes
Camera Geotag No
Permalink 54e3dd46ed2a89d9900003c3
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