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Distribution, Density and Longitudinal Zonation of Dryopoid Beetles (Coleoptera: Dryopoidea) in Southwestern Virginia
Henry H. Seagle, Jr. and Albert C. Hendricks
The American Midland Naturalist
Vol. 107, No. 2 (Apr., 1982), pp. 219-227
Published by: The University of Notre Dame
Stable URL: http://www.jstor.org/stable/2425372
Page Count: 9
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Fifteen dryopoid species in five families were collected from the Clinch and North Fork Holston river basins in southwestern Virginia. Eleven of the species were in the family Elmidae. Stenelmis crenata and Psephenus herricki were the most widely distributed species occurring in 11 of 13 streams. Highest dryopoid densities occurred in September and December, and overall mean dryopoid densities for Brumley Creek and the North Fork Holston River were 186 and 2545 m-2, respectively Stenelmis crenata, Optioservus trivittatus, P herricki and Dubiraphia sp. were the most abundant species with overall mean densities of 1204, 903, 247 and 122 m-2, respectively. Oulimnius latiusculus and Promoresia tardella were dominant in the headwaters of Brumley Creek and S. crenata, Optioservus trivittatus, P herricki and Dubiraphia sp. were most prevalent in the lower reaches of Brumley Creek and the North Folk Holston River. Microcylloepus pusillus aptus occurred almost exclusively in the North Fork Holston River. Number of dryopoid species among streams was correlated with highest alkalinity, hardness and conductivity (r≥0.76; p < 0.05). Stream ecosystem function is suggested as an important factor in zonation.
The American Midland Naturalist © 1982 The University of Notre Dame