A new genus of Cephidae, Curvicephus gen. nov., together with three new species – C. dianzang gen. et sp. nov., C. xiaoi gen. et sp. nov., and C. lii gen. et sp. nov. – is described from Yunnan and Xizang, China. The new genus differs from all other known genera of the family by a combination of distinctive features: an elongate ovipositor sheath distinctly and evenly bent upwards; the lateral ocelli positioned behind the line connecting the posterior margins of the eyes; the distance between the antennal toruli narrower than the distance between the inner orbits and the torulus, and about half the distance between the antennal torulus and the anterior tentorial pit; claws quite slender with the inner tooth much longer than apical tooth; head with a distinctly concave area above the antennal toruli; abdomen long and slender.

Due to the conspicuous variation in the present morphology, particularly in the male sex (typically the legs and penis valve), the Asitrichiosoma subgenus was established by Malaise, 1939 of the Trichiosoma genus. Based on COI data, the genetic distance between Asitrichiosoma and Trichiosoma is 0.0878, and this genetic distance is significantly different (p < 0.001) from the average genetic distance (0.0256) among the species within the genus Trichiosoma. Based on morphological and molecular data, we recognize Asitrichiosoma as a valid genus. The differences between Asitrichiosoma and Trichiosoma are discussed in detail. The newly elevated genus is revised, and seven new species are described: A. bomei Yan & Wei, sp. nov.; A. brevicorne Yan & Wei, sp. nov.; A. shennong Yan & Wei, sp. nov.; A. sinense Yan & Wei, sp. nov.; A. omei Yan & Wei, sp. nov.; A. poecilomallosum Yan & Wei, sp. nov.; A. nigropilosum Yan & Wei, sp. nov. Descriptions, remarks, illustrations, and a key to the known species of Asitrichiosoma are provided. Four new combinations are proposed: A. himalayanum (Malaise, 1939), A. anthracinum (Forsius, 1930), A. bombiforme (Takeuchi, 1939), A. sikkimense (Konow, 1897), among which A. bombiforme (Takeuchi, 1939), A. sikkimense (Konow, 1897) and A. gansuense Yan & Wei, 2025 are re-described and illustrated. The distribution of the genus is also briefly discussed.

Syspastoxyelidae is an extinct basal hymenopteran lineage currently known only from mid-Cretaceous Burmese amber. Here, we describe a new genus and species, Cilioxyela setosa gen. et sp. nov., based on a well-preserved female specimen from the Hukawng Valley, northern Myanmar. The new taxon is assigned to Syspastoxyelidae based on diagnostic characters, including strongly proximally condensed forewing venation, a composite first flagellomere formed by fused ancestral segments, tibiae bearing dense robust spines, and segmented cerci. Cilioxyela gen. nov. differs from all previously described genera by a unique character combination, most notably, a distal forewing veinless membrane lacking longitudinal corrugation and conspicuously elongated marginal setae, together with a narrowed forewing, elongate pterostigma and anal cell, and distinctive antennal segmentation. These features support the establishment of a new genus. Comparative analysis indicates that distal forewing morphology in Syspastoxyelidae is more variable than previously recognized. The presence or absence of longitudinal corrugation in the distal forewing membrane likely reflects genus-level differentiation rather than a stable family-level synapomorphy. The new genus also supports a tentative division of Syspastoxyelidae into at least two morphologically cohesive groups, pending testing through additional fossil discoveries and quantitative phylogenetic analyses. The discovery of Cilioxyela setosa expands the known morphological disparity of Syspastoxyelidae and highlights evolutionary plasticity in distal forewing architecture among early Hymenoptera, contributing to a better understanding of morphological diversification in mid-Cretaceous forest ecosystems.

Nematus trochanteratus (Malaise, 1931) (Hymenoptera: Tenthredinidae) is a monophagous herbivorous pest that exclusively attacks willow trees (Salix spp.), and exerts significant ecological and economic impacts on forest and garden ecosystems. To date, no high-quality reference genome has been reported for this species, restricting research on its genetic evolution and gene function. In this study, we generated a high-quality chromosome-level genome assembly of N. trochanteratus by integrating PacBio HiFi long-read sequencing, Illumina short-read sequencing, and Hi-C chromatin conformation capture data. The final assembled genome size is 188.07 Mb, with a scaffold N50 of 23.87 Mb, and 9 pseudo-chromosomes were successfully constructed. Using insect universal single-copy orthologs (BUSCO), we estimated the genome completeness at 97.2%. A total of 11,540 protein-coding genes, repetitive sequences accounting for 21.74% of the genome, and diverse non-coding RNA genes were identified by systematic annotation. This genome provides a valuable resource for phylogenetic and functional genomic studies of hymenopteran sawflies.

Tenthredinidae (Hymenoptera: Tenthredinoidea), the most species-rich sawfly family, features a controversial subfamily classification, particularly regarding Eriocampa Hartig, 1837, Conaspidia Konow, 1898, and their relatives. In this study, we sequenced and characterized 15 complete mitochondrial genomes from Eriocampa, Eriocampopsis Takeuchi, 1952, and Conaspidia, and reconstructed the phylogeny of Tenthredinidae using a mitogenomic dataset including 69 species from 16 subfamilies. The mitochondrial genomes of these genera exhibited genus-specific tRNA rearrangements within the IQM and ARNS1EF clusters. Phylogenetic analyses using both Maximum Likelihood and Bayesian Inference consistently recovered (Eriocampa + Eriocampopsis + Conaspidia) as a monophyletic lineage distinct from other subfamilies of Tenthredinidae. Divergence-time estimates indicate that the Eriocampa lineage diverged from other tenthredinids around the Late Cretaceous-Paleocene boundary (~70 Ma) and diversified during the Eocene. This timing coincides with the radiation of their host plants (Araliaceae, Betulaceae, and Juglandaceae). We also compared the morphology of Eriocampinae with that of other subfamilies of Tenthredinidae and summarized the diagnostic characters of Eriocampinae. Integrating morphological and mitogenomic evidence supports the recognition of Eriocampinae Rohwer, 1911 stat. nov. This study not only clarifies the phylogenetic position of these genera but also provides new insights into the coevolutionary history between sawflies and angiosperms.

This study describes a new sawfly species from China, Siobla longitheca, which is specialized on the invasive Phytolacca americana and completes its entire life cycle using this host. Its intensive feeding damage effectively inhibits the growth and reproduction of P. americana, making it a promising candidate for the biological control of this invasive plant.

Abstract Animal mitochondrial rRNAs are commonly viewed as structurally reduced, yet sponge mt SSU rRNAs range from compact to highly expanded structures. Using nine conserved structural anchors, we compared 216 taxonomically resolved records from four classes and 22 orders, including 16 freshwater Spongillida and 200 marine sponges. Twelve homologous hypervariable substructures were coded as structural types, and their ordered combinations as composite types. We identified 38 structural types and 62 composite types across molecules ranging from 853 to 2,019 nt. Hexactinellida and freshwater Spongillida were each uniform for a distinct composite type but differed markedly in overall structure: hexactinellid mt SSU rRNAs were compact, whereas those of Spongillida were long and contained four to five candidate insertion regions. These results show that a conserved scaffold can accommodate extensive lineage-associated structural variation and provide a practical framework for comparing highly divergent mitochondrial rRNAs.

The Aglaostigma niuae group is established, and its diagnosis is briefly discussed. Four new species of the A. niuae group from China are described and illustrated: A. hejunhuai sp. nov., A. leucotarsalina sp. nov., A. niuae sp. nov., and A tricoloricorne sp. nov. A key to all species of the A. niuae group is provided.

Anaxyelidae, a relict lineage of sawflies, are represented by a single extant species today but displayed remarkable Mesozoic diversity. Here, we describe the Orthosyntexis mascula sp. nov. from mid-Cretaceous Burmese amber. The new species can be readily distinguished by its forewing, with a normally sized, uniformly sclerotized pterostigma; 1-Rs shorter than 1-M; cell 1M more than twice as long as wide; absence of 1r-rs; 1-Cu, distinctly shorter than 2-Cu; 3-Cu shorter than 4-Cu; 2m-cu shorter than 1m-cu; and 3rs-m twice as short as 4-M. In the hind wing, abscissa 2-M+Cu present, 1-M shorter than 2-M, crossvein m-cu absent, and cell R1 closed. Mesotibia with two apical spurs. Examination of high-resolution photographs of Kempendaja jacutensis enables a revised interpretation of its venation, confirming its placement in Anaxyelinae. Comparative analysis of syntexine taxa further reveals that variation in the forewing crossvein 1r-rs consistently corresponds with hind wing venation, suggesting that multiple evolutionary trajectories may have existed within Syntexinae. These findings not only expand the known diversity of Cretaceous Anaxyelidae but also provide new evidence for reconstructing the evolutionary history and internal diversification of Anaxyelidae.

This flowchart outlines the comprehensive workflow of the study, integrating diverse bioinformatics tools (e.g., NCBI2GO, SSU-align, bpRNA) and their sequential interactions. Key steps, such as data preprocessing, structural prediction, and evolutionary analysis, are depicted with their respective outputs (e.g., standardized records, consensus templates, domain annotations) listed on the right, connected via directional arrows to illustrate data flow.

In this paper, a new species of Pristiphora is described and illustrated, P. brevitheca sp. nov. collected in Hebei Province from China. Based on the morphological characteristics of females and males and the maximum likelihood tree analysis based on COI, it is determined that this new species belongs to the P. abietina group. Partial mitochondrial genome and 21 tRNA secondary structures of the new species are described. The partial mitochondrial genome (16,187 bp) contains 36 genes: 13 protein-coding genes, 21 tRNAs, and 2 rRNAs. Notably, trnQ and the control region (CR) are missing from the assembly. The A+T content of P. brevitheca mitochondrial genome is 80.9%. Phylogenetic analysis showed that P. brevitheca belongs to the P. abietina group, and this also supports the monophyly of the group. The consumption of Picea meyeri (Pinaceae) needles by the new species results in the complete defoliation of some trees. Some biological characteristics of the new species are also provided.

Wolbachia, a widespread endosymbiotic bacterium, profoundly impacts insect hosts by distorting reproduction and population dynamics. Despite extensive laboratory research, its long-term effects on host evolution in nature remain poorly understood, especially the genomic consequences linked to disruptions in sex determination and reproductive processes. We present the first telomere-to-telomere (T2T) genome assembly of the sawfly Analcellicampa danfengensis and the complete genome of its symbiotic Wolbachia. Comparative population genomics across six Analcellicampa species revealed that Wolbachia-infected populations show starkly different demographic signals. While uninfected populations show similar demographic signals for both sexes, infected populations exhibit a lower apparent effective population size (Ne) in males, which may reflect a recurrent male bottleneck effect driven by Wolbachia-induced male scarcity. Genomic scans identified positively selected genes associated with reproductive functions, sensory perception, neural development, and longevity, suggesting that Wolbachia likely manipulates critical host pathways to promote its transmission. These findings provide direct genomic insights into Wolbachia as an evolutionary force, highlighting specific host genes and regions under selection resulting from these altered evolutionary dynamics. This work provides deeper insights into host-endosymbiont coevolution and has important implications for evolutionary theory and pest management strategies.

Platycampus Schiödte, 1839 is distributed in Europe and East Asia, with ten described species. A new species, P. rufitegularis sp. nov., is described and illustrated from Zhejiang Province, China, representing the third Platycampus species recorded in China. Diagnostic illustrations of morphological characters for all three Chinese species and a key to the world species of Platycampus are provided. The partial mitochondrial genome of P. rufitegularis (16,103 bp; GenBank: PX129881) was assembled into 36 genes, including: 13 protein-coding genes, 21 tRNAs, and 2 rRNAs; trnD and the control region (CR) are missing from the assembly. The A+T content is 80.1%. Phylogenetic analyses resolved P. rufitegularis as sister to P. amurensis Zinovjev, 1986, and this clade forms a supported lineage within the monophyletic genus Platycampus.

Mitogenomes are known for their structural dynamics and the complexity of their rearrangement patterns. However, their utility in metazoan comparative biology has not been fully exploited. Vertebrate mitogenomes are now sufficiently representative to allow the development of more advanced methods for comparing genome architecture. Furthermore, the relatively robust phylogeny of vertebrates at higher taxonomic ranks allows us to infer the patterns of genome evolution accordingly. In this study, using amphibians as an example, we performed data cleaning and manual annotation on 1777 samples from the NCBI and identified 88 rearrangement types, most of which were clade specific. In addition, we quantified genomic changes in an evolutionary framework and obtained stepwise growth curves of the architectural changes. This study provides new perspectives for understanding the evolution of the mitogenomes in amphibians and is expected to facilitate the qualitative and quantitative development of mitogenomes research.

The new tenthredinid Palaeocaiina menatensis gen. et sp. nov. is described and illustrated from the Paleocene of Menat (Puy-de-Dôme, France). Although its preservation complicates the observation of several key characters useful to distinguish between tenthredinid subfamilies, we decided to place this new taxon within the tribe Allantini of the subfamily Allantinae. Its venation of fore- and hind wings combined with the shape of its ovipositor sheaths leads us assume that Palaeocaiina gen. nov. is possibly related to the extant genus Caiina Wei, 2004 distributed in the east Palearctic. Interestingly, this new genus is the oldest known fossil of the subfamily Allantinae.

Luberotenthredo cerestensis gen. et sp. nov. is the first record of the sawfly family Tenthredinidae from the Oligocene of Céreste (Southern France). This taxon is described and illustrated based on a well-preserved specimen. This genus resembles the extant genus Perineura (subfamily Tenthredininae, tribe Perineurini) with which it shares forewing venation similarities and numerous morphological characters. This new taxon is the first fossil representative of the tribe Perineurini and can be used as a calibration point for future investigation of the diversification of the family Tenthredinidae.

Quantifying the features of mitochondrial genome structural variation is crucial for understanding its contribution to complexity. Accurate quantification and interpretation of organizational diversity can help uncover biological evolutionary laws and patterns. The current qMGR approach accumulates the changes in two adjacent genes to calculate the rearrangement frequency RF of each single gene and the rearrangement score RS for specific taxa in the mitogenomes of a given taxonomic group. However, it may introduce bias, as it assigns scores to adjacent genes rather than to rearranged genes. To overcome this limitation, we propose a novel statistical method called qGO to quantify the diversity of gene organization. The qGO method, which is based on the homology of gene order, provides a more accurate representation of genome organizational diversity by partitioning gene strings and individually assigning weights to genes spanning different regions. Additionally, a comprehensive approach is employed for distance computation, generating an extensive matrix of rearrangement distances. Through experiments on more than 5500 vertebrate mitochondrial genomes, we demonstrated that the qGO method outperforms existing methods in terms of accuracy and interpretability. This method improves the comparability of genomes and allows a more accurate comparison of the diversity of mitochondrial genome organization across taxa. These findings have significant implications for unraveling genome evolution, exploring genome function, and investigating the process of molecular evolution.

Phylogenomic approaches have recently helped elucidate various insect relationships, but large-scale comprehensive analyses on relationships within sawflies and woodwasps are still lacking. Here, we infer the relationships and long-term biogeographic history of these hymenopteran groups using a large dataset of 354 UCE loci collected from 385 species that represent all major lineages. Early Hymenoptera started diversifying during the Early Triassic ∼249 Ma and spread all over the ancient supercontinent Pangaea. We recovered Xyeloidea as a monophyletic sister group to other Hymenoptera and Pamphilioidea as sister to Unicalcarida. Within the diverse family Tenthredinidae, our taxonomically and geographically expanded taxon sampling highlights the non-monophyly of several traditionally defined subfamilies. In addition, the recent removal of Athalia and related genera from the Tenthredinidae into the separate family Athaliidae is supported. The deep historical biogeography of the group is characterised by independent dispersals and re-colonisations between the northern (Laurasia) and southern (Gondwana) palaeocontinents. The breakup of these landmasses led to ancient vicariance in several Gondwanan lineages, while interchange across the Northern Hemisphere has continued until the Recent. The little-studied African sawfly fauna is likewise a diverse mixture of groups with varying routes of colonization. Our results reveal interesting parallels in the evolution and biogeography of early hymenopterans and other ancient insect groups.

Wolbachia, a widespread endosymbiotic bacterium, can reshape the evolutionary fates of its insect hosts by distorting reproduction and altering population dynamics. Despite extensive laboratory research, its long-term effects on host evolution in nature remain poorly understood, particularly regarding genetic mechanisms underlying changes in sex determination and reproduction. Here, we report the first telomere-to-telomere (T2T) genome assembly of the sawfly Analcellicampa danfengensis and the complete genome of it symbiotic Wolbachia. Comparative population genomics of six closely related Analcellicampa species revealed that Wolbachia-infected populations experience marked changes in sex-specific demography. While uninfected species maintain balanced genetic features between males and females, infected species show a persistent reduction in male effective population size alongside a stable or even growing female population, ultimately driving males toward extinction. Genomic scans identified positively selected genes associated with reproductive functions, sensory perception, neural development, and longevity, suggesting that Wolbachia manipulates critical host biological pathways to promote its transmission. These findings provide direct genomic evidence that Wolbachia acts as a powerful evolutionary force, reshaping host genomes in a way that disrupts Fisher's principle, ultimately driving female-biased demography and the extinction of males at evolutionary timescales. This work provides deeper insights into host-endosymbiont coevolution and has important implications for evolutionary theory and pest management strategies. ### Competing Interest Statement The authors have declared no competing interest.

Tomostethus sinofraxini Wang & Wei (a new name is proposed for Tomostethus fraxini Niu & Wei, 2022: Tomostethus sinofraxini Wang & Wei, nom. nov.), an emerging sawfly pest of the Chinese ash, Fraxinus chinensis, is now endemic to Beijing, Tianjin, Hebei, and Shandong provinces. Given the severity of its infestation and the speed of its range expansion, we studied the phylogenetic relationship of T. sinofraxini with other sawfly species and its life history to be better informed for the management strategies. The nearly complete T. sinofraxini mitogenome is 16,169 bp in length and encodes 2 ribosomal RNAs (rrnL and rrnS), 22 transfer RNAs (tRNAs), and 13 protein-coding genes. The nucleotide composition is biased toward adenine and thymine (A + T = 81.7%). In comparison to the architecture of the ancestral insect mitogenome, 2 transposition events occur on the IQM tRNA cluster, rearranging it from IQM to MQI. Our phylogenetic analysis suggests that T. sinofraxini belongs to a group composed of paraphyletic subfamilies Blennocampinae and Heterarthrinae. In addition, to document its life history, we observed T. sinofraxini development at 2 geographical locations in Beijing, China, with different altitudes. At Jiulong Mountain, with a higher altitude and a lower average temperature, the developmental time of egg, larval, and adult stages was 19%-31% longer than that observed at the Chinese Academy of Forestry. A basic understanding of biological traits and molecular signatures is the critical first step to develop an integrated pest management framework for this emerging pest of the Chinese ash.