Sexing Phidippus audax, and other things...

A couple days ago I introduced you to Wallis, our beloved Daring Jumping Spider. Well, I'm sorry to say she has left us. The railing post is vacant now, except for the female Theridion that's built a web outside. I don't know what happened to Wallis. Perhaps something ate her, or more likely she became weary of my efforts to feed her and study her, and crawled away in search of a new home. At any rate, she's gone. I miss her. If I ever find another specimen, I'm seriously considering catching it and keeping it in a terrarium. Many fans of the species do so.

In spite of Wallis's disappearance, I have many photos and much information still to share with you. For instance, how do you determine the sex of a Phidipuus audax specimen? I wondered that myself, and after some research I've come up with these general guidelines:

1. The specimen must be mature in order to determine the sex.
2. The palps of an adult male will be much more swollen than those of an adult female.
3. The colors of an adult male's markings and chelicerae will be more striking (and sometimes different) than those of an adult female.
4. If you can catch the specimen, this is a surefire way of sexing it: An adult female has an epigynum on the ventral side between the spiracles (lungs).
5. An adult male has larger chelicerae, bigger eyes, a larger cephalothorax, and a more slender abdomen than an adult female.

Also, concerning markings, Wallis is unusual because she has light orange spots on her abdomen, as opposed to the normal white. Juveniles have orange markings but become white upon maturity. It's not as common to see the spider retain the orange into adulthood.

I've sexed Wallis as female because her palps are slender, without bulbous ends, and her markings are not bold-colored. I was unable to catch her to look for the epigynum, so this determination isn't necessarily accurate. Interestingly, another specimen approached her on the railing one day. It had the normal white markings. I'm curious as to whether it was a male seeking a mate, or a female encroaching on Wallis's territory?

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Wallis