Southern México (Puebla, Oaxaca, Chiapas, Tabasco): Two weeks (31 October–15 November, 2004), funded by the NSF REVSYS grant. REVSYS collaborator Dr Oscar Francke travelled ca. 4,800 km through xerophytic scrub, tropical deciduous scrub forest, mixed oak-pine forest, pine forest, and tropical rainforest, at elevations ranging from 45m to 2,600 m in the Mexican states of Puebla, Oaxaca, Chiapas, and Tabasco, collecting spiders, opiliones, palpigrades, schizomids, scorpions, acari, pseudoscorpions, and Onychophora for the ATOL and REVSYS projects. Francke was accompanied, during the first week, by Gabriel Villegas (Ph.D. student) and Ricardo Paredes (M.S. student), both from the Instituto de Biologia, UNAM, and, during the second week, by Adolfo Ibarra (Technician, Entomology Collection, Instituto de Biología, UNAM) and Hector Montaño (B.S. student in the Facultad de Ciencias, UNAM). Approximately 500 specimens, were collected, including 2 palpigrade species, one schizomid species, one onychophoran species, a new Diplocentrus species and possible new Centruroides species.