Dysdera crocata?

[Deer Stalker]

Asked by a freind to ID this Spider someone had found. I told him it is probably Dysdera crocata, but would try to get conformation.

So what do you reckon?

[Meta menardi]

Dysdera certainly, could be erythrina or crocata from what I can see.

[Deer Stalker]

Originally Posted by Meta menardi

Dysdera certainly, could be erythrina or crocata from what I can see.

Hi Meta

How would you tell the two apart?

[Venger]

Do we have a size and location for this.
From what I can see, the lack of dorsal spines on femur IV suggest that this is Dysdera erythina, though thats not 100% confirmed.

[Venger]

Originally Posted by Deer Stalker

Hi Meta

How would you tell the two apart?

I'm going to jump into this one if you don't mind Meta.

Size and location is one aspect, D crocota is the larger of the two, but that doesn't always help if they aren't full grown

Dorsal spines on femur IV is an easier way of telling them apart, see photos below.


Dysdera crocota, photo by Tom Murray, notice the dorsal spines circled.


Dysdera erythrina, © Photo by Jorgen Lissner, notice lack of spines on femur IV, circled.

Hope this helps

[Deer Stalker]

Hi Venger, thanks for breaking it down for me.

It was found by someone walking Down a highstreet in a town called Shirley on the edge of Southampton (south of England).

From head to tail it was about 20mm.

Don't know if you can see any better from this pic?

[Venger]

Well the location works for them both.
I think your sizes are off though, D.crocota, the larger of the two only reaches 15mm, D.erythrina is smaller at around 10mm (though everything seems to be larger than the books tell us so add on a couple of mm to those lengths)
All I can see on the last picture is hairs, but no spines, so therefore D.erythrina, but the larger size tell me it's D.crocota??
so now I don't know

[Wild-Woman]

Whatever! I wouldn't want to be a woodlouse walking down an alley with one of them coming the other way!

[Meta menardi]

Thanks for that, Venger, I knew the theory of the spines on the legs, but couldn't have elucidated it like you did. I rarely see D. crocata here, despite a garden full of woodlice and a nasty habit of wandering it at night with a head torch (I tell the neighbours I am looking for Haddock).

[naturegirl]

Venga, you are such a knowledgable boy! I wish I had half of your brain!

My daughter who lives and works in Ashford, Kent said she came upon this beastie locally in the last week! Hope this is of interest to you.

Naturegirl