Reared adults of Potamanthellus unicutibius Nguyen & Bae, 2003 from China (Ephemeroptera, Neoephemeridae).

BACKGROUND

The nymphs of Potamanthellus unicutibius Nguyen & Bae, 2003 possess filtering mouthparts and modified fore-legs. However, no adults are known.

NEW INFORMATION: In this study, both nymphal and imaginal stages of this species were collected and reared from China. Morphological examination reveals that these specimens differ markedly from all other members of Potamanthellus Lestage, 1931. In addition to the filtering nymphal morphology, the males of this species are characterised by more distinctly developed penes, longer tibiae and cerci and smaller compound eyes compared to those of Potamanthellus. Significantly, its distinct penes not only validates its independent species status, but also reveals the evolutionary process of the reduction of neoephemerid male genitalia and provides the original clue of the vestigial penes in several other lineages of the order Ephemeroptera as well.