Those are two males killing each other. Males grab the female's head firmly in their mouth, and she generally lets him. Looks brutal, but it gets their wimmenz in the mood.
Ventral bites are an attempt to mutilate a rival male's hemipenes, rendering him unable to mate.
Thanks their still at today.
Yep! that's how it was DR I guess they killed each other. Gone now.
Perhaps one of the rarest spiders in the world...
this unidentified Aptostichus species came from a very distinct habitat type- finely eroded sediment at the base of a west-facing cliff- thorough sampling of the entire site (nearly two miles) failed to produce another specimen. Im sure there are at least two more somewhere in the vicinity, however as i failed to find an additional specimen in the entire area, the outlook for this species' survival seems bleak.
I'll try to find wandering males come fall, but if that fails, I'll have to consider this yet another doomed species of aptostichus :(
EDIT: Yay! Not bleak the slightest! This turned out to be Aptostichus atomarius the "San-bernadino hills" trapdoor spider. However as common as it is, it prefers very steep hillsides.. so collection will be difficult if I want more. The good news is males are quite easy to find!
Last edited by smokehound; 04-17-2014 at 04:03 AM.