Atrax sp. (genus)

Funnel-web spider at Black Range, NSW

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Identification history

Hadronyche sp.

28 May 2020

AndrewMcCutcheon

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User's notes

I found this large male Funnel-web Spider with help from one of our resident yellow robins, while I was digging out a dead shrub. The robin was watching for any insects I might disturb. After having caught a few insects, the bird pounced once more on what looked like a large meal, only to jump back in fright when it realized what it was up against - this funnel-web in a defensive posture with its front legs raised and fangs ready to bite. Body length was approx. 25 mm.

5 comments

KerriLee wrote:

29 May 2020

Nice spider! It's a female ... no enlarged pedipalps. The head region (caput) of the carapace doesn't appear to rise as steeply as you see in Hadronyche. Paul is now cross-checking, but it may be Atrax sutherlandi

KerriLee wrote:

29 May 2020

Hi Andrew ... did you happen to get a side-on shot? It would help in distinguishing Atrax from Hadronyche

AndrewMcCutcheon wrote:

29 May 2020

Hi KerriLee, I did not take any side-on images, as I was not aware at that time of the raised carapace being a diagnostic feature of Hadronyche, or that there was more than one genus of Funnel-web spider. I found out later after reading some information about Funnel-webs, and concluded my spider was a Hadronyche, as the carapace appears to be raised after looking at some other images I did not upload. Here are a couple more of these shots, not perfect, but the shadows and reflections on the carapace in the head region indicate it is raised.

KerriLee wrote:

31 May 2020

Hi again Andrew, Paul and I have been reviewing various sightings of Atrax and Hadronyche in the past couple of days and we think yours is a good match for Atrax. The differences are quite subtle in females, but in Atrax the cephalothorax is longer (relative to width) than in Hadronyche. Your photo #1 shows this quite well. The head region of the cephalothorax (ie the caput) is raised in both Atrax and Hadronyche, but in Hadronyche it is a much steeper rise. Your photo #4 looks very much like Atrax to me. Photo #3 is a tricky angle – it accentuates the caput rise and so I think photo #4 is the more telling image. (As an example of this effect, take a look at the photos of a male Atrax in sighting https://atlasoflife.naturemapr.org/Sightings/3871015.) The other difference between Hadronyche and Atrax is the shape of the last (tip) segment of the longest pair of spinnerets. In Hadronyche they are triangular, with a width to height ratio of ~0.6. In Atrax, they are finger-shaped .... with a width to length ratio of ~0.25. Perhaps you can check this in your images?

AndrewMcCutcheon wrote:

1 Jun 2020

Hi Kerri-Lee, after looking at Paul's sighting of A. Sutherlandi I can see that the male is of a much lighter build than the female I have here. Unfortunately I don't have good enough images to examine the spinnerets. Back in November 2012 I saw several large funnel-webs (both sexes) at Dead Horse Gap near Thredbo Village, which look similar to the Black Range funnel-web, but with a cephalothorax that is equal in length and width. I suspect they may be Hadronyche alpine. I could upload the Dead Horse Gap funnel -webs, but not sure if Thredbo is within the area covered by ALCW. Not being an expert on spiders I am more than happy to go with your identification of our Black Range funnel-web.

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