Ting Yang

Siphlonuroidea is a superfamily within Ephemeroptera, yet the phylogenetic relationships among its constituent families and their placement relative to other mayfly lineages remain unresolved. To address these questions, we generated and analyzed 16 newly assembled mitochondrial genomes from 14 species across Ephemeroptera, including three species of Ameletidae, four of Siphlonuridae, and nine mitochondrial genomes from seven species of Isonychiidae. Comparative mitogenomic analysis revealed two distinct tRNA gene rearrangement patterns within Siphlonuridae, including trnI-trnQ-trnM-trnQ-trnM-trnQ-trnM-trnQ-trnM and trnI-trnM-trnQ-trnM. In contrast, all Ameletidae mitogenomes share an identical rearrangement of trnI-trnQ-trnM-trnM, which constitutes a potential synapomorphy supporting the monophyly of this family. Compositional analysis further showed that Siphlonuridae and Ameletidae exhibit significantly higher and highly similar A+T contents, clustering together in hierarchical analyses. This characteristic contrasts sharply with Isonychiidae, which displays markedly lower A+T content. Phylogenomic inference based on the PCG12 dataset supports a sister-group relationship between Siphlonuridae and Ameletidae, with this clade itself forming the sister group to a well-supported clade of Isonychiidae and Heptageniidae. Divergence time estimation places the origin of the Ameletidae and Siphlonuridae lineage in the Late Jurassic (174.71 Mya), while Isonychiidae diverged in the Early Cretaceous (136.81 Mya). In conclusion, Siphlonuridae and Ameletidae show a closer affinity and belong to Siphlonuroidea. Isonychiidae shares a closer relationship with Heptageniidae and remains outside Siphlonuroidea. Siphluriscidae is recovered as the sister lineage to all other extant Ephemeroptera, confirming its status as the earliest-diverging extant mayfly lineage.

Archaeognatha is phylogenetically positioned as the basal lineage relative to all extant insect orders and comprises approximately 600 described species. The internal phylogenetic relationships and divergence times within this ancient order have long been a subject of scientific debate. In this study, we assembled 14 mitochondrial genomes from species within the genera Pedetontus and Pedetontinus to clarify the phylogenetic relationship and estimate divergence times within Archaeognatha. Phylogenetic analyses revealed that both Machilidae and Machilinae are paraphyletic; Pedetontinus included in this analysis formed a well-supported monophyletic clade, whereas the sampled Pedetontus species were not recovered as a monophyletic clade. Divergence time estimates indicate that Archaeognatha originated during the Late Carboniferous (301.15 Mya, 95% HPD: 298.88–303.67 Mya), with subsequent diversification spanning from the Mesozoic era to the present. The adaptive radiation of epiphytic bryophytes and potential coevolutionary interactions between plants and insects are proposed to have significantly contributed to the diversification of Archaeognatha. Based on multiple lines of evidence, we propose that the current morphological criteria for species delineation within Pedetontus (Pd.) require revision to better reflect its evolutionary history. In the branch-site model analysis, when Pd. silvestrii—collected from temperate regions—was designated as the foreground branch, two positively selected sites were detected at the 66th position of the Cytb and the 34th position of ATP6. When Pd. hainanensis and Pd. bawanglingensis—collected from tropical regions—were used as the foreground branches, six positively selected sites were identified at the 622nd position of Cytb, the 499th position of ATP6, and the 623rd, 873rd, 1106th, and 1141st positions of COI.

Bristletails (Microcoryphia) represent a relatively understudied group of class Insecta. These wingless hexapods, which retain numerous plesiomorphic structures, remain less well understood compared to most other insect lineages. Through detailed morphological examination of specimens collected from southern China, we describe six new species (Pedetontus (Verhoeffilis) elegans sp. n. from Zhejiang; P. (V.) hezhouensis sp. n., P. (V.) jinxiuensis sp. n., and P. (V.) nanningensis sp. n. from Guangxi; and P. (V.) shenzhenensis sp. n. and P. (V.) xanthospilus sp. n. from Guangdong) of subgenus Verhoeffilis Paclt, 1972. This subgenus is distinguished from other members of the Petrobiinae by several diagnostic features: paired ocelli shoe-shaped (fusiform-shaped) and submedian; two pairs of retractile vesicles on abdominal segments II–V; parameres restricted to coxite IX; penis opening small and apical; male genitalia not exceeding coxite IX; and ovipositor of primary type. The new species can be distinguished from known species and each other by the morphology of the compound eyes, maxilla, labial palps, legs, and genitalia; here, we provide detailed illustrations, tables, and descriptions. Furthermore, we sequence the COX1 gene to construct a phylogenetic tree of Microcoryphia. This contribution increases the total number of reported Pedetontus species in China to seventeen.

Bristletails (Microcoryphia) represent a relatively understudied group of class Insecta. These wingless hexapods, which retain numerous plesiomorphic structures, remain less well understood compared to most other insect lineages. Through detailed morphological examination of specimens collected from southern China, we describe six new species (Pedetontus (Verhoeffilis) elegans sp. n. from Zhejiang, P. (V.) hezhouensis sp. n., P. (V.) jinxiuensis sp. n. and P. (V.)nanningensissp. n. from Guangxi, P. (V.)shenzhenensis sp. n. and P. (V.)xanthospilus sp. n. form Guangdong) of subgenus Verhoeffilis Paclt, 1972, this subgenus distinguished from other members of the Petrobiinae by several diagnostic features: paired ocelli shoe-shaped (fusiform-shaped) and submedian; two pairs of retractile vesicles on abdominal segments II–V; parameres restricted to coxite IX; penis opening small and apical; male genitalia not exceeding coxite IX; ovipositor of primary type. The new species can be distinguished from known species and each other by the morphology of the compound eyes, maxilla, labial palps, legs, and genitalia, here, we provide detailed illustrations, tables, and descriptions. Furthermore, we sequenced the COX1 gene to construct a phylogenetic tree of Microcoryphia. This contribution increases the total number of reported Pedetontus species in China to seventeen.