Status and ecological indicator potential of Heterosternuta sulphuria populations (Coleoptera: Dytiscidae: Hydroporinae) in Arkansas

An endemic hydroporine diving beetle first collected in 1955 and with only 4 specimens collected since, Heterosternuta sulphuria, is an aquatic species of greatest conservation need in Arkansas.  Surveys to determine current population status have resulted in 34 additional records, a determined habitat of undisturbed perennial headwater stream margins, and rearing and description of the previously unknown larvae.  In its current distribution range in northwest Arkansas where impending land development threatens major headwater stream networks, no beetles were collected from perennial sites within heavily urbanized watersheds or with heavy cattle use. These habitat-specialist beetle populations could be effective ecological indicators for monitoring environmentally-sensitive land development and agricultural conservation practices.  We are currently determining with genetics analysis if H. sulphuria has low capacity to colonize new habitats and the overall degree of population isolation.  Their potential involvement in the mitigation of environmental disturbances in headwater (source) reaches, either by monitoring introduced populations or by protecting existing populations, would enhance biological conservation further down the stream continuum.