Gnaphosa sp.

[jsloan]

Gnaphosa sp. (Gnaphosidae)

This adult female is so sleek and colorful I had to post a picture! It just molted a few days ago, but I haven't been able to figure out the species yet. Based on what the keys describe for this genus, it looks like I'm going to have to dissect out the epigyne and look at it from the inside. If, or when, I figure it out I'll post an update. BL = 7.5 mm

 

[cacoseraph]

that looks like a much prettier version of my "old enemies"

gnaphosidae were my bane for many years when hunting for tiny mygs... when i was just getting started. they constantly confused me and had me digging out the blasted spider out of its webbing only to find it was another freaking gnapho. then when i finally started actually catching the mygs i was like.. man, these really don't look anything like gnapho webs =P

 

[spider pest]

that looks like a much prettier version of my "old enemies"

gnaphosidae were my bane for many years when hunting for tiny mygs... when i was just getting started. they constantly confused me and had me digging out the blasted spider out of its webbing only to find it was another freaking gnapho. then when i finally started actually catching the mygs i was like.. man, these really don't look anything like gnapho webs =P

This is funny. I found something that looks similar to the spider posted above a couple days ago, although larger. When I first lifted the log it was under and saw something dark in some webbing, I had a "could it be?" moment. Still, cool spider.

 

[marclar]

Whats also funny, yesterday on the way home from school I saw one, and bent down real fast cus' I thought it was an a affinis(didnt have glasses on) cus they the only mm's we get in ireland, but it was just one of these guys, did the exact same today.

 

[PhilR]

Whats also funny, yesterday on the way home from school I saw one, and bent down real fast cus' I thought it was an a affinis(didnt have glasses on) cus they the only mm's we get in ireland, but it was just one of these guys, did the exact same today.

You are not going to see Atypus affinis wandering about

 

[cacoseraph]

well, i mean... mature males are found in all kinds of goofy places... but i wouldn't want to bet a penny on seeing a mature female wandering around.

though, my buddy from texas *did* score a MF female trapdoor spider FROM HIS LIVING ROOM FLOOR one time! he has also caught a ~5-6"BL Scolopendra heros from the same room. all stuff that wandered in, 100%! only in Texas, man... only in TX =P

 

[zonbonzovi]

The spinnerets look strange- very blunt...maybe just an anomaly from the pic.

 

[cacoseraph]

one of my simple field diagnostics for gnaphosidae is short, blunt, squared spinners. those ones do like a tiny bit more angular than i would expect... but i've also never taken such a nice pic of one so that could be it =P


now i'm kind of wanting to see a video of a gnapho spinning their tube webs. hmm... maybe i could make a rig or something. catch a fem almost as big as sloan's. hmm hmm.

 

[jsloan]

The spinnerets look strange- very blunt...maybe just an anomaly from the pic.

Nope, that's the way they are. Here's another shot from directly above:

 

[jsloan]

Most of the readers in this forum probably already know this, but for everyone else I thought I'd mention how I determined the genus for this spider. Spiders in the genus Gnaphosa have a "serrated keel" on the retromargin (inside margin) of each chelicera. According to Dondale and Redner*, no other genus of Gnaphosidae in north america has this feature. Here's a picture I took showing the keel on the chelicera of a Gnaphosa parvula, as an example:

Speaking of the "blunt" spinnerets, if I get the chance I'll take a closeup picture and post it. Might not be until the weekend, though.

* The Ground Spiders of Canada and Alaska, 1992

 

[Zoltan]

Hey John,

I didn't know it, so thanks for posting this. Doesn't retromargin mean outside margin, though? Or more precisely, ventral or posterior margin?

 

[jsloan]

one of my simple field diagnostics for gnaphosidae is short, blunt, squared spinners.

Speaking of spinnerets, I was fooled by a spider I collected last August. Along with the squared ends, I also look for some separation between the spinnerets for gnaphosids, but that feature wasn't so apparent in this particular spider. That and the general appearance and size (BL = 10 mm) made me think it was a clubionid of some kind. But, the separated cylindrical spinnerets showed up under magnification and it turned out to be Orodrassus canadensis (Gnaphosidae):

 

[jsloan]

Doesn't retromargin mean outside margin, though? Or more precisely, ventral or posterior margin?

Retromargin = posterior margin or edge of the fang furrow, which is the "inside" margin next to the maxillae.

Promargin = anterior margin or edge of the fang furrow; the "outside" or front side.

It's not easy to see, but the side of the chelicera in the picture above is the inside, normally tucked up against the maxillae and labium.

 

[Zoltan]

Retromargin = posterior margin or edge of the fang furrow, which is the "inside" margin next to the maxillae.

Promargin = anterior margin or edge of the fang furrow; the "outside" or front side.

I'm starting to get it now. I guess it's because I'm used to mygalomorph chelicerae, where the promargins are the parts on the inside of the chelicerae. Here's a crappy illustration of what I mean, ventral view:

 

[cacoseraph]

Speaking of spinnerets, I was fooled by a spider I collected last August. Along with the squared ends, I also look for some separation between the spinnerets for gnaphosids, but that feature wasn't so apparent in this particular spider. That and the general appearance and size (BL = 10 mm) made me think it was a clubionid of some kind. But, the separated cylindrical spinnerets showed up under magnification and it turned out to be Orodrassus canadensis (Gnaphosidea):

lanky legs for a gnapho, too. would not have been my first guess, at all

 

[jsloan]

I'm starting to get it now. I guess it's because I'm used to mygalomorph chelicerae, where the promargins are the parts on the inside of the chelicerae. Here's a crappy illustration of what I mean, ventral view:

Okay, now I see where you were coming from. That makes sense, because if you rotate the mygalomorph chelicerae in your drawing so that the fangs end up pointing toward each other, as in true spiders, the promargin would then be along the front of the spider and the retromargin would end up on the inside next to the maxillae.

 

[jsloan]

A closeup of the spinnerets (ventral view):