Nymphs of the Northeastern Nearctic Species of Neoleptophlebia Kluge, 1997 and Paraleptophlebia Lestage, 1917 (Ephemeroptera: Leptophlebiidae)

Although male imagos of the three species of Neoleptophlebia and seven species of Paraleptophlebia known from the northeastern Nearctic region (i.e., eastern Canada and northeastern United States) are reasonably well-known and can be reliably keyed, nymphs are not as well-known and often cannot be reliably identified using the existing keys. Descriptions of nymphs of the northeastern Nearctic species of Neoleptophlebia and Paraleptophlebia vary in completeness and frequently lack important morphological details or information on variation that occurs with development or between different sexes. Thus, all existing keys based on these descriptions have problematic couplets, and some do not treat all 10 species. To address these problems a new key to nymphs of the 10 northeastern Nearctic species of Neoleptophlebia and Paraleptophlebia is presented here based on a reassessment of the morphology of nymphs and exuviae of reared specimens. The new key uses several new characters in combination with previously known diagnostic characters to increase the probability of achieving accurate species determinations. In support of the key each species is discussed regarding key characters, specifically regarding variability that may cause interpretation problems. Regional distribution and habitat also are discussed for each species. Lastly, comments are provided on the apparent vulnerability of each species to large scale changes in its occurrence within the northeast Nearctic region as a result of the predicted effects of climate change on regional aquatic habitats.