(1) Background: Chironomids are biological indicators, playing an important role in monitoring and assessing the changes in water ecosystems. Mitochondrial genomes have been widely applied as a molecular marker to analyze the taxonomy and phylogeny of insects. However, knowledge of the mitogenomes of Chironomus species is scarce at present, which limits our understanding of the evolutionary relationships among Chironomus. (2) Methods: In our study, the mitogenomes and their basic structure of 12 Chironomus species and one Microchironomus species were newly sequenced. Combined with reported mitogenomes, a total of 15 mitogenomes of Chironomus were selected for a comparative mitogenomic analysis and phylogenetic reconstruction of Chironomus. (3) Results: Each mitogenome of the Chironomus species has the typical 37 genes and a control region. The basic structure of the whole mitogenomes of Chironomus species is relatively conservative, and the genetic arrangements stay the same as the ancestral mitogenome. (4) Conclusions: Our study enriches the library of mitogenomes of chironomids and provides a valuable resource for understanding the evolutionary history of Chironomus.

Chironomid is the most important macroinvertebrate species in aquatic ecosystem. Chironomus represents the most important genus of the Chironomidae. However, the species of this genus lack a high-quality assembled genome. Here, a high-quality chromosome-level assembled genome of Chironomus striatipennis which is an important model organism in aquatic ecological detection and toxicological application has been reported. The assembled genome size of C. striatipennis was 181.84 Mb, with a scaffold N50 value of 54.13 Mb. Furthermore, the molecular mechanism of adaptive evolution of Chironomid to benthic environment was elucidated by combining transcriptome data of different stages. The complete metabolic pathway of Hemoglobin was clarified in C. striatipennis for the first time to suggests the regulatory mechanism underlying its adaptation to benthic living. The expansions of CYP450s gene family related to detoxification explain its tolerance to the harsh environment. The key gene family, JHAMT, involved in biosynthesis of juvenile hormone are substantially expanded. The expansion of JHAMT genes and the regular regulation of juvenile hormone and ecdysone explain the developmental plasticity of C. striatipennis. In this study, it was also found that C. striatipennis is more dependent on JNK signal pathway induced metamorphosis than Drosophila melanogaster. This study provides some views into genetic basis of tolerance and adaptation of C. striatipennis to harsh benthic environments and lays a part of the foundation for the adaptive evolution of benthic animals.

A novel supramolecular framework, catena-poly[[[aqua(2-phenylquinoline-4-carboxylato-κO)silver(I)]-μ-4,4'-bipyridine-κ(2)N:N'] dihydrate], {[Ag(C16H10NO2)(C10H8N2)(H2O)]·2H2O}n, has been synthesized and structurally characterized. The Ag(I) centres are four-coordinated and bridged by 4,4'-bipyridine (4,4'-bipy) ligands to form a one-dimensional Ag-bipy chain. The Ag-bipy chains are further linked together by intermolecular O-H···O and O-H···N hydrogen-bonding interactions between adjacent chains, resulting in a three-dimensional framework.

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Tanytarsus xinglongensis Lin, a new species within the Tanytarsus aterrimus species group, is described and illustrated based on adult males from Oriental China. It is characterised by T-shaped tergal bands, rectangular superior volsella, and very short and stout stem of median volsella.