The mount is called "Uma-Nori" in at least two style in the Bujinkan. It translates to "horse mount" as if your riding a horse. Those of you who have done drills where uke tries to escape the mount and all you can do is try and keep the mount position will see where the name comes from.
The guard is called "seitai", not sure if this is a correct term but I have never seen it used elsewhere except from a Kosen/Bujinkan teacher.
The standing guard was poorly seen in January on UFC Fight Night on Spike when Silva from Brazil fought Tim Sylvia. Silva was just holding on to prevent from being pounded and made Tim's shorts fall down. He did ok but if he got higher onto the ribs it would have been better. In some styles in the Bujinkan you jump up and do dô-jime and either sutemi or strike the guy, its not a postion you want to "hang-out" in or risk getting slammed on your back. Would really hurt on the dirt or pavement but on the mat it would still hurt but as many of you have seen you can survive the slam or get knocked out from it.
Eric Weil
"Kuji first, Taijutsu last"