Rhopalocera of the Llano Estacado: biosystematics, biogeography, and ecology

At approximately 96,000 km2, the Llano Estacado is the largest nonmountainous land formation in North America. Prior to this research, in terms of Rhopalocera, it was one of the least-studied large distinct areas remaining on the continent. A total of 188 species of Rhopalocera known or implicated (including dubia) to occur in or adjacent to the Llano Estacado and its associated escarpments are identified in an annotated checklist. Discussion of biosystematic positions and nomenclature, with special attention to species and subspecies levels, identifies the taxa within the context of the literature. Biogeographical occurrences in the Llano Estacado and its associated escarpments are summarized, with new range information being provided for many species.

Data from an intensively studied 13,926 km^ section of the Llano Estacado and adjacent Rolling Plains enables collective use of the 101 species recorded there as a bioindicator group in representation of the Comanchian and Kansan biotic provinces, their interface, and habitats. Seasonal occurrences are also addressed. Habitats are divided into range, mesa, escarpment, playa, urban, cotton, grain sorghum, and alfalfa categories. Phi coefficient values are computed and clustered for biotic provinces and habitats using UPGMA, single linkage, and complete linkage sequential agglomerative hierarchical nested polythetic techniques with methods of arbitrary tie-breaking, single linkage resolution, and suboptimal fusions available for each clustering algorithm. Total species richness values for the Comanchian (S = 71) and Kansan (S = 78) biotic province sections are lower than that of their interface (S = 92) . The cotton and grain sorghum categories form a ball cluster in each dendrogram and are most restrictive in terms of species richness (S = 32). The escarpment habitat is consistently the final object to cluster in each method and has the highest species richness (S = 92) of the habitat categories. Ecological findings include evidence that both natural conditions and anthropogenic factors in the form of large-scale monocrop agriculture and range grazing have collectively contributed to formation of a refugium on the biotic province interface. Recommendation is made for its preservation.