Unidentified stretch spider - 4th Jan 2010

[Bruce Williams]

Stony Stratford, Bucks.

Help with identification and any other related info appreciated.





Bruce

[aeshna5]

Looks like a Tetragnatha species to me.

[Bruce Williams]

Thanks aeshna . Do we know if it's male or female?

I've done a fair amount of Googling on Tetragnatha and found 7 UK species (so far) of which extensa and montana seem to be the most common.

I also read that the term "tetragnatha" means "four jawed" anyone know why the name was given to this family of spiders?

This individual was on an exposed area of (metal) wall just inside a tunnel running under the A5. There is a pond close by. Temp was around 0º - would we expect it to be active?

Bruce

[No.9 Spider]

Hi Bruce, photographs of the sternum of Tetragnatha species can narrow down the species (see the recent post by lesinlondon).

P.S. thanks for the Xmas greeting, belated greetings to you and yours for this year!


No.9 Spider

[Bruce Williams]

Thanks No.9.

Interesting....I wonder (at 0ºC) how this spider would have reacted to being flipped onto its back? If the opportunity presents in the future I'll try doing it just to see.

Bruce

[Bruce Williams]

....just to clarify my last comment: I wondered if the spider would be fairly torpid at low temperature.

Bruce

[No.9 Spider]

Originally Posted by Bruce Williams

Thanks No.9.

Interesting....I wonder (at 0ºC) how this spider would have reacted to being flipped onto its back? If the opportunity presents in the future I'll try doing it just to see.

Bruce

Give her a chance to thaw her feet out

........and they're usually less active when it's cold, and being cold blooded will seek out the sun and warmth (those were the days!).


No.9 Spider

[Bruce Williams]

Thanks No.9 Spider - Yes that makes sense, she (it's a female then?) was on a sunny patch of wall (metal) about 1.5m inside the tunnel.

Bruce

[Geoff F]

Firstly, 'four jawed' refers to the large chelicerae and maxillae which give the impression of having four jaws.

It's definitely not a mature male but, lacking expert knowledge in this species, I wouldn't totally rule out a sub adult male due to the lack of clear abdominal markings.

T. extensa and T. pinicola tend to be lighter coloured, but this isn't reliable particularly with juveniles. T. pinicola is smaller, weighing in around 5 or 6 mm for a female.

[Bruce Williams]

Geoff - Thanks for the info on name and help with id.

Unfortunately I can't state size with total confidence .

I usually shoot at closest focus (max magnification) then calculate subject size based on ratio of subject:sensor. If for any reason I shoot at any other focus point I try to take a reference shot at full mag. In this instance although there is no reference shot, I have a nagging feeling that I did not shoot at closest focus.

If I did shoot at closest focus then this spider measures 5mm - not particularly inconsistent with my memory of the spider.

Bruce