Thread subject: Diptera.info :: spider

Posted by mariki on 18-02-2008 13:45
#1
Cannot find the ID

Eindhoven (The Netherlands) 7-02-2008 on a bark of a birch.
size of the body 5-6 mm
Thanks in advance

Posted by jorgemotalmeida on 18-02-2008 15:24
#2
This is a Tetragnathidae spider. Tetragnatha sp. juvenile. With specimen it is not possible to reach species level unless it reaches imago phase. ;)

Posted by zcuc on 19-02-2008 22:29
#3
How it's possible to tell a spider is juvenile? It's simple with flying insects but spiders always look the same :D

Posted by Juergen Peters on 20-02-2008 01:55
#4
Hello, zcuc!

zcuc wrote:
How it's possible to tell a spider is juvenile? It's simple with flying insects but spiders always look the same :D


1.) From the size (adult Tetragnathas from species which come into account are bigger than 5-6 mm),
2.) from the "general jizz", and
3.) most importantly ;): there are no adult Tetragnathas in the Netherlands in February - so this must be a juvenile (of the species T. montana or extensa, which are adult in late spring/early summer; I would vote for T. montana, which is very numerous here at the moment and does not only reside besides water like extensa).

Posted by mariki on 21-02-2008 22:24
#5
Thanks for your replies. There is an area of water not too far, maximum 10 m away of the birch. I do not know how close of the water T. extensa is supposed to live. I have also profile picture of the spider, can it help for the determination of the species?

Thank you in advance.

Posted by Juergen Peters on 21-02-2008 22:55
#6
Hello, mariki!

mariki wrote:
water not too far, maximum 10 m away of the birch. I do not know how close of the water T. extensa is supposed to live.


10 m would be near enough. I doesn't need to be so near - horizontal net over the water - like this one...:
http://insektenfo...adid=10609
http://www.foto-u...enke_1.jpg
;)

I have also profile picture of the spider, can it help for the determination of the species?


I'm afraid that would not help, sorry. The two species can only be identied definitely by examination of the genitalia (female epigyne or - preferably - male palpi). And that wouldn't work with a juvenile anyway...

Posted by jorgemotalmeida on 22-02-2008 13:37
#7
Juergen Peters wrote:
Hello, zcuc!

zcuc wrote:
How it's possible to tell a spider is juvenile? It's simple with flying insects but spiders always look the same :D


1.) From the size (adult Tetragnathas from species which come into account are bigger than 5-6 mm),
2.) from the "general jizz", and
3.) most importantly ;): there are no adult Tetragnathas in the Netherlands in February - so this must be a juvenile (of the species T. montana or extensa, which are adult in late spring/early summer; I would vote for T. montana, which is very numerous here at the moment and does not only reside besides water like extensa).



all correct, Juergen. And the pale colour is typical for juveniles too. :)