The Imaginal Characters of Neoephemera projecta Showing Its Plesiomorphic Position and a New Genus Status in the Family (Ephemeroptera: Neoephemeridae).

Abstract

Simple SummaryThe phylogenetically problematic Neoephemeridae is a small family of the order Ephemeroptera, including four genera reported previously. They are genera Neoephemera (in Nearctic region), Ochernova (Central Asia), Leucorhoenanthus (West Palearctic) and Potamanthellus (East Palearctic and Oriental regions), which were geographically isolated until the Neoephemera projecta Zhou and Zheng, a species reported in 2001 from Southwestern China, connected them together. In this work, the imaginal stage and biology of Neoephemera projecta are first observed and described. Furthermore, a series of autapomorphies and plesiomorphies of it are recognized and discussed. Morphologically and biologically, this species is significantly different from other genera and deserves a new plesiomorphic position in the Family Neoephemeridae. Therefore, a new genus Pulchephemera gen. n. is established to reflect its primitive position and intermediate characters of two clades of the family. In addition, some shared characters of this new genus and the family Ephemeridae provide a new perspective or possibility on the phylogeny of Neoephemeridae within the order Ephemeroptera.The newly collected imaginal materials of the species Neoephemera projecta Zhou and Zheng, 2001 from Southwestern China, which is linking the other genera of the family Neoephemeridae, are described in detail. Nymphs are also photographed for the first time. The morphology of this species shows some characters of the other genera in Neoephemeridae and several autapomorphies. However, most characters can be seen as plesiomorphies of the family. Specifically, the dorsal-oriented fimbriate gills, projected frons and slim labial palpi in nymphs plus large reddishly pigmented wings, many crossveins, 4-segmented forceps with a relatively long basal segment, fused penes and unforked anal vein show that this species is closer to the taxon Fossoriae rather than to the previously considered Potamanthidae. To reflect its primitive position, a new genus, Pulchephemera Zhou gen. n., is established for this species, Pulchephemera projecta comb. n. Its eggs and observed biology are also described.