Monday, April 30, 2012

Some Salticid Research Results

It’s been eight months since I stumbled across this impressive female jumping spider at the Vanderwater Conservation Area, an active, robust specimen between 15 to 20 mm in length. I strongly suspected it was genus Phidippus, but despite putting in no small amount of time on the 'net researching images of spiders, I was unable to identify it until now.

This spider encountered on the trail a couple of days ago was very similar in size and build, and this time my efforts at IDing it – about two hours of research on the ‘net – met with success. I think this is Phidippus princeps. The irridescent pale bluish-grey chelicerae can be seen in the following image.

The brownish-red on the abdomen is pale compared to the color of the spider I photographed last August. The photos of Jumping Spiders - Genus Phidippus by Tom Murray at PBase illustrate how dramatically variable these spiders can be.

Large forward-facing eyes endow this predator with excellent vision (among the best in the invertebrate world), and the remainder of its eight eyes are mounted high on raised nubs on the carapace, giving it a wraparound view of its surroundings.

The spider felt uncomfortable with my being so close with the camera. In addition to waving its front legs and showing its chelicerae, it did this ...

Interesting behavior ... a Six-spotted Fishing Spider assuming the same posture, again, it was in response to my presence.

A few more trips down memory lane to catch up on Salticidae images that have been sitting in my "unidentified" files for about a year. In the course of my Phidippus princeps research I found Bev Wigney's excellent Salticid Photo Galley at PBase, and I believe this small jumper (about 5 mm in length) is genus Pelegrina, a Peppered Jumper. And she's gravid and ready to lay eggs any time, by the look of her.

This female Jumping Spider has captured a Robber Fly, a fearsome predator in its own right. Had the fly seen the spider first, the predator/prey outcome here might well have been different! With the help of the aforementioned photos at PBase and at BugGuide.Net I was able to identify this arachnid as Phidippus clarus.

The best match I could find for this male is genus Evarcha. Making a species identification solely on the basis of a photograph is chancy, but this Evarcha falcata at the Encyclopedia of Life looks like a dead ringer to my inexperienced eye. But – a little more research divulged that Evarcha hoyi is the only species extant in my area (eastern North America), so E. hoyi it is.

Females encountered in the same location as the males, E. hoyi seems a reasonable conjecture. Is my guess correct?

When I started photographing and researching odonates I had no field guides to help me sort out males and females – which can often appear radically different – of the same species. One way around this was to hopefully observe a mating pair of dragonflies, and this technique works for spiders as well ... a mating pair of Evarcha hoyi.

Despite some obvious differences in the palps, overall shape and slightly different markings, I initially misidentified this jumping spider as possibly a species of Eris (Spider Snapshots), but having done more reading and research I think it's actually genus Pelegrina.