Western Black Widow (<i><a href="//commons.wikimedia.org/wiki/Latrodectus_hesperus" title="Latrodectus hesperus">Latrodectus hesperus</a></i>), I believe. This family of spiders is notorious for the females' cannibalistic behavior of consuming the males post (or even pre) mating. (In some species the male even wants to be eaten).
The females are sleak and beautiful. This girl's hour glass is unfortunately not as full as can be.
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