Great Basin Naturalist


Three species of shore bugs (Hemiptera: Saldidae) and 10 species of brine flies (Diptera: Ephydridae) were collected at Sylvan Springs (Wyoming section of Yellowstone National Park, USA), an area containing both acid and alkaline thermal springs. The fauna consists of both widespread (e.g., shore bugs Saldula comatula Parshley and Saldula explanata [Uhler] and shore flies Atissa litoralis [Cole] and Scatella stagnalis [Fallén]) and Yellowstone Park–endemic species (e.g., Saldula nr. arenicola and the shore fly Ephydra thermophila Cresson). The ratio of adults to nymphs of the numerically dominant shore bug Saldula nr. arenicola is higher along heated margins (11–12:1) than along near-ambient-temperature margins (0.6–2:1) of a thermal channel at Sylvan Springs; this may reflect differences in food availability, osmoregularity, thermal tolerance, predation, or other factors. Shore flies include species typical of acid (E. thermophila) and alkaline (Paracoenia bisetosa [Coquillett] and Paracoenia turbida [Curran]) springs.