Neoleptophlebia mollis ( Eaton, 1871: 88 )

Burian, Steven K., 2024, Nymphs of the Northeastern Nearctic Species of Neoleptophlebia Kluge, 1997 and Paraleptophlebia Lestage, 1917 (Ephemeroptera: Leptophlebiidae), Zootaxa 5521 (1), pp. 1-65 : 11

Neoleptophlebia mollis ( Eaton, 1871: 88)

Cloe mollis Hagen, 1861 (nomen nudum)

Leptophlebia mollis Eaton, 1871 (original description)

Leptophlebia mollis Hagen,1861 (nomen nudum)

Paraleptophlebia mollis ( Eaton, 1871) (combination)

Description of Nymph: Ide 1930: 209; Gordon 1933: 123; Leonard & Leonard 1962:74

Near final instar nymphs of N. mollis are similar in color to, but slightly smaller than those of N. adoptiva . In the late spring and early summer, N. mollis nymphs are conspicuous in the same habitats occupied by N. adoptiva . Nymphs of N. mollis can be recognized by having sharp posterolateral projections only on abdominal segment IX (as in Fig. 4a ); the base of mandibular incisors of the left mandible extended well above the anterior margin ( Figs. 7b,c ) and incisors of the left mandible distinctly curving inward; and the frons with only a small pale spot anterior to the median ocellus ( Fig. 8 ). These characters seem consistent on nymphs from mid-development to the final instar. The previous comments concerning interpretation of the posterolateral projections of abdominal segment IX relative to what can occur on the segment VIII tergite of some nymphs for N. adoptiva also apply to some nymphs of N. mollis . The correct interpretation of the mandibular incisor character requires locating the anterior margin of the left mandible between the molar surface and the incisors. If a line drawn across the anterior margin passes well below the bases of the incisors, then the incisors are considered to extend beyond the anterior margin. Although the incisor character can be observed on both mandibles ( Figs. 7a–c ), the right mandible frequently does not express this character consistently ( Fig. 7a ). The left mandible does express this character well ( Figs. 7b,c ), thus for comparative purposes with other species, the left mandible should be used when possible. Mandibles of N. mollis can be observed without slide mounting by using the technique described for viewing mandibles of N. adoptiva .

Neoleptophlebia mollis is widely distributed and common, with records in 12 of the 14 states and provinces ( Table 2). Only RI and NL-I, lack records. The absence of records for RI is likely the result of sampling effort, but the lack of records from NL-I may reflect an actual absence because of the difficulty of dispersal across a strait to an offshore island. The widespread distribution of N. mollis is reflective of its wide habitat tolerances being able to use suitable microhabitats in both small streams and larger rivers, similar to N. adoptiva . Thus because N. mollis can occupy such a wide range of the available stream habitats it is likely one of most secure species in this genus across its northeastern range with regards to changes in regional hydrology predicted to occur because of climate change ( Hicke et al. 2022).

Figures

FIGS. 1–4: gills and abdominal tergites VIII–X of Neoleptophlebia and Paraleptophlebia nymphs. 1. N. adoptiva gill 4, 2. P. praepedita gill 4, 3a. N. assimilis tergites VIII–X, 3b P. praepedita tergites VIII–X, 3c. P. volitans tergites VIII–X, 3d. P. moerens tergites VIII–X, 4a. N. adoptiva tergites VIII–X, 4b. P. guttata tergites VIII–X.

FIGS. 5–8: mouthparts and dorsal view of the head of Neoleptophlebia nymphs. 5a. right mandible (ventral view) of N.adoptiva, 5b Left mandible (ventral view) of N. adoptiva 6. dorsal view of head of N. adoptiva, 7a. right mandible (ventral view) of N. mollis, 7b-c. left mandible (ventral view) of two N. mollis specimens showing differences in position of outer incisors, 8. dorsal view of head of N. mollis.