[1] Univ Calif Berkeley, Museum Vertebrate Zool, Berkeley, CA 94720 USA
[2] Univ Calif Berkeley, Dept Integrat Biol, Berkeley, CA 94720 USA
[3] Univ Nacl Autonoma Mexico, Inst Biol, Mexico City 04510, DF, Mexico
[4] Univ San Carlos, Museo Hist Nat, Guatemala City, Guatemala