Systematics and Cladistics of the North American Subgenus <I>Anadaptus</I> Casey (Genus <I>Anisodactylus</I> Dejean) and a Geographic Information System Analysis of the Biogeography of Included Species

Abstract

The classification, cladistics, and biogeography of taxa of the subgenus Anadaptus Casey (genus Anisodactylus Dejean) are analyzed. The subgenus is a monophyletic group. There are seven valid species, two with transcontinental ranges in North America, four in western North America, and one in central and southern Mexico. Anisodactylus nivalis Horn, 1880 is a new junior synonym of Anisodactylus alternans LeConte, 1851. Lectotypes designated are Anisodactylus alternans LeConte, 1851; Anisodactylus chalceus LeConte, 1859; Anisodactylus nivalis Horn, 1880; Anisodactylus rotundangulus Bates, 1878; and Anisodactylus viridescens LeConte, 1862. Geographic information system (GIS) techniques are used to analyze the biogeography of taxa. Species are concentrated in two biodiversity centers in the West. Biodiversity decreases sharply north of the larger biodiversity center because of cool summer temperatures. The species restricted to western North America have much more variation in character states than do species occurring elsewhere. Geographic ranges in eastern and central North America are much larger than those in most of the West because of broad areas of unfavorable habitats and more patchy climatic zones in the West. The shapes of geographical distributions are east-west elongated in eastern and central North America and predominantly north-south elongated in the West. Large regions of the current biodiversity centers had climates unfavorable for Anadaptus during the Wisconsin glacial period. If species originated and accumulated over long periods of geologic time in the West, centers of biodiversity there had to shift geographically in response to climatic changes.