Diversity of litter-dwelling beetles in the Ouachita Highlands of Arkansas, USA (Insecta : Coleoptera)

A survey of forest litter-inhabiting Coleoptera was conducted in deciduous forests of the Ouachita Mountains in western Arkansas during 1991-1992. A t otal of 102 Berlese samples were collected, weighed, and processed during t he 12-month study. From 741 kg of sifted forest litter, we counted and sort ed 10 663 adult beetles representing 46 families and 400 species. The famil y Staphylinidae was taxonomically and numerically dominant, comprising 46% of species and 63% of individuals. Problems in assessing species richness o f forest litter Coleoptera faunas result from a lack of taxonomic revisions , occurrence of sex-limited diagnostic characters, and inadequate informati on about larval-adult species associations and life histories. A randomized species accumulation curve indicated that species addition ranged from 14 species per sample during the first ten samples to 1.5 species per sample d uring the final ten. Richness estimates generated from the empirical data r anged from 434 species (Michaelis-Menten and Coleman richness estimators) t o 590 species (second order jacknife). The area sampled is biogeographicall y significant because it harbors numerous habitat-restricted species that a re endemic to the Ouachita Mountains or the Interior Highland region, as we ll as disjunct populations of species that are also found in the southern A ppalachian Mountains. Deciduous forest habitats of the Ouachita Mountains, particularly beech-maple riparian forest, should be given special considera tion in forest conservation planning because of their significance as refug ia for these and other endemic and disjunct arthropods.