A zoogeographic and taxonomic analysis of the Dytiscidae of Tennessee with an emphasis on the pulcher-undulatus species group of hydroporus (Adephaga: Coleoptera)

Species of the aquatic beetle family Dytiscidae are extremely common in almost all aquatic habitats. Despite this, there have not been any comprehensive faunal studies of this family in Tennessee.

Therefore, a thorough effort was made to collect specimens in the state. About 250 collections were made within Tennessee and another 100 in adjacent areas. A rather complete list of 95 species has been assimilated. Approximately l0% of the taxa were undescribed.

The pulcher-undulatus group (Sensu Fall, 1923) is partially taxonomically analyzed. Three groups within the pulcher-undulatus group will eventually deserve subgeneric rank: the triangularis-pilatei group, pulcher group, and undulatus group. Keys, diagnoses, descriptions, collection localities, and natural history notes are presented based on Tennessee material. In addition, type localities, North American distributions, and taxonomic notes are given.

The zoogeographic derivation of the North American dytiscid fauna is discussed, with an emphasis on the southeastern regions of the United States.

Finally, the dytiscid faunas of nine physiographic regions within Tennessee are analyzed and compared using the Jaccard coefficient of similarity and a cluster analysis. The results indicate the nine regions compared formed four major groups: the Mississippi Alluvial Plain; the Coastal Plain Upland and Mississippi Embayment; the Highland Rim, Ridge and Valley, Cumberland Plateau, and Blue Ridge Provinces; and Central Basin and Dissected Highland Rim. The most speciose region was the Highland Rim.