Male Spiders: Thick-Jawed Orb Weaver, and Cobweb Spider

2015 October 28

I found this moderately orange spider prowling around the wall near our porch light on June 15, 2015. His body was about 4 mm long.

Like a lot of the spiders I’ve been photographing lately, he has the enlarged pedipalps that mark him as a male.

He also has a kind of a high “forehead” that his eyes are located on.

At first I thought he was maybe a Sheetweb Weaver, but while they looked similar the match wasn’t exact, so I posted him on BugGuide. And I was advised that he actually looked more like a Thick-Jawed Orbweaver in the genus Pachygnatha. And, of the ones posted, he looks most like Pachygnatha autumnalis (although most of those have a more prominent orange stripe running down the abdomen). Not only do these look right, they also tend to rest in that particular stretched-out pose.

Later, on June 23, 2015 I found this superficially similar spider in approximately the same place.

While he’s clearly not the same species as the first one (the abdomen shape and markings were different), they have enough features in common (like the long, pale, knob-kneed legs; the “foreheads”, and very similar pedipalp shape) that at first I thought that they might be in the same family, if not the same genus.

It is hard to see the eyes clearly in this next picture, but I think he has a row of six, with two above.

If I’m right about the eyes, then that pretty much means that this second one isn’t related to that first one. The thick-jawed orb weavers (and their relatives, the long-jawed orb weavers) look like they have their eyes in two rows of four, instead. And the general body shape, pose, and the hairs on the legs actually don’t look the same as that first one. This second one also seems to have much less pronounced jaws (chelicerae) now that I look at it more closely.

So, since I was doing a better job of deciding what it wasn’t than of deciding what it was, I put this one up on BugGuide too. It took a while for someone to recognize it, but finally Mandy Howe recognized it as probably being Neottiura bimaculata. This is a small cobweb weaver that, based on the distribution maps, appears to prefer colder climates (BugGuide shows it in Quebec, British Columbia, Washington State, Wisconsin, and now Michigan)

Comments are closed.