Misumena vatia (Clerck, 1757) Discussion

goldenrod crab spider

Comments on June 30, 2007 Observation

Bev Wigney
45.1465, -75.6088
1

Submitted: June 30, 2007 at 6:38:03 AM MST

This is a report of sightings from two days. On June 29th, I found my first sighting of a female guarding an egg case at the farm this summer. She was wrapped over an egg case chamber formed from a bent milkweed leaf that had been sealed shut. Of interest was that this female had and extra pair of pink lines in addition to the usual pink bands on the abdomen. This spider was found in an oldfield meadow in one of the more open pastures here at the farm. Photos (2): Spider on egg case: http://www.pbase.com/image/81399959
Spider close-up: http://www.pbase.com/crocodile/image/81399958
Second group of sightings are from June 22nd. I found a male and 4 juvenile female spiders within an area of about 5 meters along a walking trail at the edge of our woodlot. All were found atop daisies. The male and one of the females had each captured a fly. Of interest -- I checked some of the daisies out in the open field and did not find any spiders in that location. I did find some young Phymata (Ambush bugs). Perhaps the daisies in the open field attract predators that would seize the young spiders, so they do better on plants within the edge of the woodlot. Photos (5): Male with prey: http://www.pbase.com/crocodile/image/81399952 Females: http://www.pbase.com/crocodile/image/81399953
http://www.pbase.com/crocodile/image/81399954
http://www.pbase.com/crocodile/image/81399955
http://www.pbase.com/crocodile/image/81399956

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Bev Wigney wrote on June 30, 2007 at 1:27:56 PM MST

Armed with the new observations about the shape of the faces of these spiders, I went back and took a look at the images of the juvenile spiders that were in the original report that sparked this discussion. Unfortunately, one of the spiders was holding prey, and another was facing in the wrong angle. However, one spider was at an excellent angle, and one was not too bad, so I made a composite of the two. I'm now fairly sure that at least one of the juvenile spiders is something other than a Misumena vatia. This is interesting. I'll try to make a point of shooting at least a couple of head shots from directly in front as this may be useful for diagnostic purposes. Here's the little composite that I've put up online -- not terrific, but I'll try to create a better one sometime soon. Btw, I got another duplicate post on my last comment. Not sure why.

http://www.pbase.com/image/81423787

(edited by admin June 30, 2007 at 2:53:19 PM MST)

Bev Wigney wrote on June 30, 2007 at 12:49:10 PM MST

David - In looking at my photos and the photos of the M. vatia and M. formosipes from BugGuide, one of the differences in the faces that strikes me as being most noticeable is that on the BugGuide shot of M. vatia, there's quite a large space between the eye area and the edge of the upper edge of the jaws. On that photo of M. formosipes, the head looks sort of squished down and the lower edge of the eye area seems to be almost touching the upper edge of the jaws (no or very little space). If that's the case, that might be a very helpful diagnostic to look for when studying younger spiders that usually generally have no markings. I've been trying to find some physical difference that doesn't rely on pigmentation, and had never really noticed the difference in the gap between the eye area and the jaws until this discussion. By the way, I did get another shot of this spider's face. I re-found her while out doing my afternoon insect walk. Here's a link to what is probably the best of the shots. Again, a large gap between the eye area and the jaw. Neat! (-:

http://www.pbase.com/image/81420266/original

(edited by admin June 30, 2007 at 2:53:55 PM MST)

David P. Shorthouse wrote on June 30, 2007 at 12:02:51 PM MST

Quoting Bev Wigney: By the way, as you can see, my reply to your note ended up in duplicate. I'll try to deleter one of them. I'm not sure why this happens, but I've had trouble with this before --I hit the submit button, but the note seems to not appear. I then have to use the back on my browser to go back to the note and hit the submit again. Usually, it works and there's just one post, but this time, I seem to have ended up with a duplicate. (edited by admin June 30, 2007 at 11:55:49 AM MST) Quote End

First, thanks for offering a great comparison of Misumena vatia and Misumenoides formosipes. Where the two co-occur - Great Lakes area to Florida - it can be quite tricky sometimes to tell them apart. Indeed, the markings on the abdomen aren't entirely effective to tell them apart, but it's a first clue. Probably the best way to distinguish the two species is the presence of a white band under the eye area in M. formosipes, which is not present in M. vatia.

Second, sorry about the bizarre glitches. It sounds to me like the system logged you off while you were writing your note so I best do some investigating.

Bev Wigney wrote on June 30, 2007 at 9:49:15 AM MST

Quoting David P. Shorthouse: Nice shots Bev! Your M. vatia looks suspiciously like Misumenoides formosipes. There's a little write-up on the "Identify" page under "Can be Confused With". Here is a great M. vatia shot of the face up close: http://bugguide.net/node/view/58080/bgimage Here is a great Misumenoides formosipes shot of the face up close: http://bugguide.net/node/view/6710/bgimage Can you confirm? Quote End

David - By the way, as you can see, my reply to your note ended up in duplicate. I'll try to deleter one of them. I'm not sure why this happens, but I've had trouble with this before --I hit the submit button, but the note seems to not appear. I then have to use the back on my browser to go back to the note and hit the submit again. Usually, it works and there's just one post, but this time, I seem to have ended up with a duplicate.

(edited by admin June 30, 2007 at 11:55:49 AM MST)

Bev Wigney wrote on June 30, 2007 at 9:44:01 AM MST

Hi David, I'm pretty sure she's M. vatia. I think the best shot of the face that I have is this image, but I may be able to get a better one if I can find her again (I probably can). To me, her face seems typical of M. vatia and not what I would call flattened down and more angular, at least it this photo. As for the V-shape, if it is just the coloration, Douglass Morse has written quite a bit about these spiders having extra sets of dots and lines in various configurations in the mesial area in addition to the lateral markings. He writes: "A small minority of individuals possesses part of a second pair of stripes that runs mesial to the lateral markings." From the paragraph on markings (quite long), I get the impression that extra markings are not that unusual. However, he also mentions that there are extremely rare instances of M. vatia with a complete "V" -- but again, very rare, and this one has just lines rather than a V. As for the depressions (quilted looking depressions) in the abdomen in the shape of a "V" - those seem to occur in just about all of the adult females, so that's not much help. I would think maybe the face might be the best indicator, and here's an image of it. If size means anything, this was a pretty large spider -- almost close to the "jumbo size" that I've seen in M. vatia. Anyhow, I'll try to get a better photo of her next time I visit her -- provided I can find the right milkweed as there are thousands in that field! http://www.pbase.com/image/81407010/original
(edited by admin June 30, 2007 at 11:57:24 AM MST)

David P. Shorthouse wrote on June 30, 2007 at 8:30:51 AM MST

Nice shots Bev! Your M. vatia looks suspiciously like Misumenoides formosipes. There's a little write-up on the "Identify" page under "Can be Confused With".

Here is a great M. vatia shot of the face up close: http://bugguide.net/node/view/58080/bgimage

Here is a great Misumenoides formosipes shot of the face up close: http://bugguide.net/node/view/6710/bgimage

Can you confirm?