Silver Scarab Beetle (Chrysina sp.)

24 January 2009, Rancho Naturalista, Costa Rica This metallic glossy silver colored beetle showed up in the lodge during mid-morning. I believe it's a species of Chrysina or Plusiotis. Can anybody identify it specifically? I'd appreciate learning more about it. You can see the trees and garden of the lodge reflected in the carapace. Panasonic Lumix LZ5