A new species of Acentrella Bengtsson (Ephemeroptera: Baetidae) from Great Smoky Mountains National Park, USA

Acentrella barbarae sp. n. is described from eggs, larvae, and imagines collected from Great Smoky Mountains National Park, North Carolina and Tennessee, USA. Larvae were collected from cobblepebble substrate in stream rapids. Life stages were associated by rearing. Eggs have longitudinal chorionic ridges with small, longitudinal furrows. Larvae are distinguished by having segment 3 of the labial palp apically rounded, abdominal terga with posteromedian projections, and tibiae and tarsi with relatively short setae on the outer margins. Imagines are distinguished by the colouration and posterior elevation of abdominal terga. Other Acentrella larvae occur in the same streams as the new species, including A. parvula, which we report from Tennessee for the first time. We provide an updated key to the larvae of North American Acentrella species.