Mitochondrial gene order is generally conserved in insects, serving as a reliable marker for tracing evolutionary history. However, the mechanisms driving sporadic structural variations remain poorly understood, particularly in hyper-diverse lineages like Tanytarsini Zav & rcaron;el 1917 (Diptera: Chironomidae). Here, we generated 66 new mitogenomes, extending mitogenomic coverage to 10 previously unsequenced genera. Our analyses reveal a distinct pocket of mitogenomic instability within the Micropsectra-group, where we identify rare gene rearrangements. Comparative reconstruction suggests that these lineage-specific patterns most likely originated from a single ancestral tandem duplication spanning the COII-ND3 region, followed by differential random loss. The observed relaxation of purifying selection and a highly distinctive Cys to Ser substitution underscore the evolutionary plasticity of this rearranged region. Furthermore, we report that the marine species Pontomyia natans Edwards 1926 possesses the longest mitogenome currently published in Diptera, driven by the expansion of intergenic spacers. Our phylogenetic analyses corroborate morphological inference regarding the Micropsectra-group's position, addressing topological uncertainties observed in previous fragment-based studies. Collectively, these findings establish the first documented case of large-scale mitogenomic rearrangement in Chironomidae, highlighting a potential link between ecological constraints and mitogenomic structural diversity.
Abstract Scymnus posticalis Sicard, 1912, an important predatory ladybird beetle, is widely distributed throughout East Asia. However, the impact of geographic isolation on their phylogeography remains poorly understood. To elucidate the phylogeographic structure among S. posticalis populations in East Asia, identify the impacts of climate change and geographic isolation on population structure, and reconstruct the species’ population demographic history, we employed whole-genome resequencing combined with an optimized MaxEnt niche model. Our genomic analyses clearly revealed that S. posticalis formed 7 distinct phylogeographic lineages, with significant genetic differentiation among these distinct lineages in East Asia. Divergence time estimation indicated that these lineages diverged sequentially from the late Oligocene to the late Miocene (27.40 to 7.19 Ma). The extent of lineage divergence exhibits a significant correlation with geographic distance, indicating that isolation by distance plays a key role in shaping the current phylogeographic patterns of S. posticalis. This study represents the first phylogeographic investigation of the genus Scymnus globally, and its findings fill a critical gap in phylogeographic research on Coccinellidae in Asia. Our findings contribute to a better understanding of how climate change and geographic barriers jointly influence the evolutionary processes in East Asian insects and provide a valuable framework for future studies on population differentiation, speciation, and phylogeography of montane insect taxa in this biodiversity-rich region.
Diaspidinae is the largest group of armored scale insects (Hemiptera: Coccomorpha: Diaspididae), with more than 200 genera and considerable ecological and economic impact. Despite their importance, relationships within Diaspidinae and the placement of its earliest lineages are still not well understood. Here, we analyze ultraconserved elements (UCEs) data to clarify the phylogeny of the group. Our dataset includes 24 genomic samples, covering all 2 tribes and 3 subtribes of the ingroup currently known from China. We employed a broad and hierarchically structured outgroup sampling to provide both proximate and distant comparative lineages, creating a stable phylogenetic framework for evaluating the internal relationships and monophyly of Diaspidinae. Using a taxon-specific Coccoidea-v4 probe set, we recovered 3,995 UCE loci, ranging from 1,093 to 3,238 loci per genome (average 2,928) for the ingroup genomic datasets alone, and 289 to 3,238 UCE loci were recovered with an average of 2,566 UCE loci with the outgroup included. Phylogenetic analyses with maximum likelihood, Bayesian inference, and maximum parsimony all strongly supported the monophyly of Diaspidinae. To our knowledge, our study is the first to use UCE data for Diaspidinae, and it also demonstrates both the applicability of UCE and the feasibility of a hierarchically structured outgroup strategy.
Abstract The Xestocephalus toroensis complex (Hemiptera: Cicadellidae) comprises a group of morphologically cryptic leafhoppers characterized by similar somatic patterns and male genitalic structures, occurring mainly in southern China and adjacent countries. Species delimitation within this complex is notably challenging due to their specialized habitat preferences, low population densities, and subtle interspecific morphological variation. To evaluate previous taxonomic hypotheses based primarily on morphology, this study reconstructs the phylogeny of the toroensis complex using a multilocus integrative approach. We analyzed 2 mitochondrial and 3 nuclear gene fragments from multiple individuals representing each putative species across their known geographic ranges. Our phylogenetic reconstructions robustly support the monophyly of the toroensis complex, with most previously recognized species recovered as distinct monophyletic lineages. A NeighborNet haplotype network resolved the samples into 12 major clusters, with mean interspecific genetic distances based on cytochrome c oxidase subunit I (COI) sequences ranging from 5% to 16%. Geometric morphometric analyses of aedeagal shape yielded groupings that were largely congruent with the clades identified by the molecular species delimitation analyses. Together, these results support the recognition of 15 species within the complex, and 7 new species are formally described and illustrated. A comprehensive diagnostic key to all species of the X. toroensis complex is provided.
The cactus fly family Neriidae (Diptera: Schizophora: Nerioidea) is a small group of morphologically distinctive acalyptrate flies characterized by a slender body, anteriorly projected antennae, and distinctly elongate legs. Current understanding of the higher-level classification, phylogeny, and evolution of Neriidae is limited, and molecular phylogenetic studies of the family are lacking. In the present study, we generated molecular datasets comprising 15 mitochondrial (13 protein-coding genes, 16S, and 12S) and 2 nuclear (18S and 28S) genes, and reconstructed the phylogenetic relationships of Neriidae using maximum-likelihood and Bayesian methods. Our results support Neriidae as a monophyletic family closely related to Cypselosomatidae and Pseudopomyzidae. The 2 previously proposed subfamilies, Neriinae and Telostylinae, are recovered as paraphyletic. Teloneria Acz & eacute;l is supported as a genus distinct from Chaetonerius Hendel. Molecular dating indicates an Eocene origin of Neriidae at ca. 48.47 Ma, with diversification of its crown group beginning around 37.84 Ma. In combination of morphological evidence, the monotypic genus Nipponerius Cresson, syn. nov. is considered a junior synonym of Stypocladius Enderlein, the latter being recognizable by its well-developed and glabrous antennal base, complete transverse suture on the mesonotum, and presence of 5 dorsocentral setae. Furthermore, we propose Paranerius continentalis Hennig, syn. nov. as a junior synonym of Stypocladius femoratus (Coquillett), comb. nov.
