Search Results (3)

The family Potamanthidae is widely distributed across the Holarctic and Oriental regions, with nymphs often utilized as bioindicators for water pollution and human-induced environmental disturbances. However, limited mitochondrial genomes (mitogenomes) have been reported for this family. This study presents the first complete mitochondrial genome sequences of two Potamanthidae species, Potamanthus longitibius and Rhoenanthus youi. The mitogenome sizes were 15,430 bp and 15,232 bp, with A + T contents of 68.79% and 66.75%, respectively. The most abundant amino acids were phenylalanine (Phe), isoleucine (Ile), glycine (Gly), and alanine (Ala), with leucine (Leu2) showing the highest relative synonymous codon usage (RSCU) value. The analysis of tRNA secondary structures revealed high conservation among the tRNAs encoded on the H-strand. Phylogenetic reconstruction, incorporating 40 species from 13 families of Ephemeroptera, confirmed the monophyly of all the families and supported a sister group relationship between Potamanthidae and Ephemeridae. Additionally, the sequence previously identified as Rhoenanthus sp. JZ-2021 was reassigned to the genus Potamanthus. This study provides valuable insights into the evolutionary relationships within Potamanthidae and lays a foundation for future phylogenetic and taxonomic research. Full article

Potamanthidae belongs to the superfamily Ephemeroidea but has no complete mt genome released in the NCBI (except for two unchecked and one partial mt genome). Since the sister clade to Potamanthidae has always been controversial, we sequenced seven mt genomes of Potamanthidae (two species from Rhoenanthus and five species from Potamanthus) in order to rebuild the phylogenetic relationships of Potamanthidae in this study. The divergence time of Potamanthidae was also investigated by utilizing five fossil calibration points because of the indeterminate origin time. In addition, because Rhoenanthus coreanus and Potamanthus luteus are always in low-temperature environments, we aimed to explore whether these two species were under positive selection at the mt genome level. Amongst the 13 PCGs, CGA was used as the start codon in COX1, whereas other genes conformed to initiating with an ATN start codon. From this analysis, UUA (L), AUU (I), and UUU (F) had the highest usage. Furthermore, the DHU arm was absent in the secondary structure of S1 in all species. By combining the 13 PCGs and 2 rRNAs, we reconstructed the phylogenetic relationship of Potamanthidae within Ephemeroptera. The monophyly of Potamanthidae and the monophyly of Rhoenanthus and Potamanthus were supported in the results. The phylogenetic relationship of Potamanthidae + (Ephemeridae + Polymitarcyidae) was also recovered with a high prior probability. The divergence times of Potamanthidae were traced to be 90.44 Mya (95% HPD, 62.80–121.74 Mya), and the divergence times of Rhoenanthus and Potamanthus originated at approximately 64.77 Mya (95% HPD, 43.82–88.68 Mya), thus belonging to the late Pliocene Epoch or early Miocene Epoch. In addition, the data indicated that R. coreanus was under negative selection and that ATP8 and ND2 in Potamanthidae had a high evolutionary rate. Full article

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. Full article