contribution to the knowledge of the arachnids in the yucatan peninsula, mexico (excluding aranae and acari)

The Chelicerata are the second group of arthropods with the highest diversity after insects and they can inhabit almost all types of environments. The most current classification recognizes 11 orders and estimates in the number of species vary from 52,000 to 100,000. We have made an extensive literature review on the diversity of arachnids in the Yucatan Peninsula (YP) (excluding spiders and ticks). In Mexico there are 834 known species which represent 6% of the worldwide diversity. In the YP 63 records were found (58 species and 5 genera) of arachnids, which represent 6.8% of the Mexican species. According to our research, 28 of the 58 species (48%) in the YP were also record in other parts of Mexico, the continent and the world. Undoubtedly, the state of Yucatan is the best represented of the YP. In order to have a better understanding of the diversity of arachnid species is important to promote biological compendiums and sampling programs, which will improve the representation of this group and probably increasing the number of local species.