Spider ID

[J-M Belley]

Found in a basement, the specimen is 2 cm long (legspan).

I think it's a specimen from Theridion genus or something like that but I'm not sure.

Take cares

J-M

 

[Richard McJimsey]

looks to me to be a steadota grossa

 

[J-M Belley]

I though about the false widow too but I'm not very good with true spider

 

[Bastian Drolshagen]

hi,
that´s no S. grossa!

 

[J-M Belley]

Do you have any idea Improver? Which genus could it be?

 

[lhystrix]

Found in a basement, the specimen is 2 cm long (legspan).

I think it's a specimen from Theridion genus or something like that but I'm not sure.

Take cares

J-M

It is most likely Enoplognatha or Steatoda.

 

[J-M Belley]

If I'll take a ventral shot does it will be easier to identify?

Thanks guys for the help

 

[Bastian Drolshagen]

hi,
I would say it´s some Theridiidae, but for any further ID a macroshot of the eyepattern would be best...

 

[buthus]

Looks like borealis (sort of).
Do you find others like it? Wanna sell it?

Im spider hunting in MN ...its around 8 deg F. 2 species so far!

 

[J-M Belley]

I'll try to get a couple of macroshot of the eyepattern and post them here.

No other specimen were found, we will not be able to sell it because it's frigging cold down here, anyway we keep it for ourselves

Thanks guys

 

[eresus]

Theridiidae - Steatoda sp.

 

[Bastian Drolshagen]

hi,
what makes you think this is Steatoda sp.?!?

 

[eresus]

general shape for ophistosoma, no strong spines on legs, tarsi IV with a row of bristles serrated (not well visible, but it is possible to see).

 

[Bastian Drolshagen]

hi,
there are more Theridiidae with an opisthosoma shaped like this.
Are the absence of strong spines on legs and a tarsus IV with a row of bristles synapomorphies of Steatoda sp.?

BTW.: I can´t see any bristles on tarsus IV on any of the photos.

 

[Bastian Drolshagen]

hi,
had to look it up since Theridiidae are not my main field of interest:

Shape of Opisthosoma: No keyfeature of Theridiidae in general and especially not Steatoda, since there are more spiders with an opisthosoma like the one this spider shows.

Abscence of strong spines on legs: Also no keyfeature of Theridiidae and Steatoda sp.

Serrated bristles on tarsus IV: Key feature of Theridiidae, but synapomorphy for ALL Theridiidae. Additionally these bristles are set ventrally on tarsus IV, so they could only be seen in the second picture.

Without knowing if a colulus is present or not it not possible to ID this spider to genus level without examining it (unless you have funded knowledge of that spider family).

Again: Why do you think this spider is a Steatoda sp. and no other Theridiidae?

 

[eresus]

hi,
had to look it up since Theridiidae are not my main field of interest:

Shape of Opisthosoma: No keyfeature of Theridiidae in general and especially not Steatoda, since there are more spiders with an opisthosoma like the one this spider shows.

Abscence of strong spines on legs: Also no keyfeature of Theridiidae and Steatoda sp.

Serrated bristles on tarsus IV: Key feature of Theridiidae, but synapomorphy for ALL Theridiidae. Additionally these bristles are set ventrally on tarsus IV, so they could only be seen in the second picture.

Without knowing if a colulus is present or not it not possible to ID this spider to genus level without examining it (unless you have funded knowledge of that spider family).

Again: Why do you think this spider is a Steatoda sp. and no other Theridiidae?

you are right once again. One way to be sure it would be to look at the sternum, unfortunately, not visible in these photos. In Steatoda, the sternum is NOT trunked in posterior part. In Enoplognatha it would stretch between the coxae IV.
With colulus, both Steatoda and Enoplognatha have that. In Enoplognatha the lateral eyes almost touch, not visible in these photos.

Really the tarsi with serrated bristles can be seen in other genus inside Theridiidae. Yep, in the second photo we see the ventral tarsi IV. It seems serrated. OK. This time I must give reason to you, Bastian. only theridiid. For genus, we need the ventral view photos. It would help to discard, at least, between Steatoda/Enoplognatha. Keep up that criticism open.

 

[Bastian Drolshagen]

hi,
sure it could be Enoplognatha or Steatoda sp. but as I mentioned: Without knowing about the presence/abscense of colulus at this spider we can´t ID it to genus level - Anelosimus/Parasteatoda/Achaearanea are also possible candidates for a positive match.
Also the lateral eyes at Steatoda almost "touch" each other:

Steatoda paykulliana

 

[eresus]

The Anelosimus I know - at least, for mediterranean region - has a middle dark band in prosoma. Also, the posterior and anterior LATERAL eyes in Anelosimus really touch each other. But, here, I don't know if there are other Anelosimus without that band.
Only I know about Anelosimus are the A. vittatus, A. pulchellus and A. aulicus.

Concerning Parasteatoda, according to the Platnick 2007, there is only one Parasteatoda that has cosmopolitan distribution - P. tepidariorum. I would like see such genus.

 

[Bastian Drolshagen]

hi,
you´re right on Parasteatoda. I was pointing on the synapomorphies, more than on distribution...
Interested in some P. tepidariorum? I could offer preserved and live specimen - got a colony of those in the basement