Patterns of diversity in the Ceratozetoidea (Acari: Oribatida): a North American assessment

Abstract

Represented globally by eight families, 91 genera and about 556 species, the Ceratozetoidea is among the most diverse superfamilies of oribatid mites. Species of Ceratozetoidea occur in forest, grassland, tundra, and semiaquatic habitats. They are found in all biogeographical regions, but are most diverse at mid to high latitudes in the Nearctic, Palaearctic, and Neotropics. The richness of the group in North America allows assessment of patterns of diversity. North America was divided into 12 geographical regions. The ceratozetoid fauna of North America comprises 125 species in 32 genera representing the families Ceratozetidae, Mycobatidae, Chamobatidae, Zetomimidae, Humerobatidae, and Euzetidae. The fauna is dominated by species of Ceratozetes, Trichoribates, and Mycobates, that represent almost 50% of the fauna. No species was found in all 12 geographical regions, and Pelopsis bifurcatus and Punctoribates palustris, the most widely distributed species in North America, were found in only eight regions; 44% (55 spp.) of the fauna was restricted to one region. The trend of increase in number of species with decreasing lati- tude was not supported, irrespective of longitudinal zone, and southern latitudes had the lowest number of genera and species. Almost 42% of species are shared with other zoogeographical regions, of which three are cosmopolitan, viz. Ceratozetes gracilis, C. mediocris, and Punctoribates punctum. Species shared with the Palearctic comprise main- ly Amphi-Atlantic, Circumboreal, and Amphi-Beringian faunal elements. Almost 59% of species are restricted to the Nearctic, dominated by species with Carolinean-Austroriparian and East-Beringian distributions. In contrast with the biogeography of other North American oribatid taxa, that of Ceratozetoidea is strongly influenced by Beringia.