The complete mitochondrial genome of the flat bug Aradacanthia heissi (Hemiptera: Aradidae)

The mitochondrial genomes of three species of Yangiella were sequenced, annotated, and analyzed. The genome length of the three species of the genus is 15,070–15,202 bp, with a typical gene number, including a control region, 2 ribosomal RNA genes (rRNAs), 22 transfer RNA genes (tRNAs), and 13 protein-coding genes (PCGs). It was found that the mitochondrial genome of Yangiella had AT bias. Except for the lack of a DHU arm of the trnS1 gene, the other tRNAs had a typical cloverleaf structure, and the codon usage preferences of the three species exhibited high similarity. In addition, tRNA gene rearrangements were observed among the three subfamilies of Aradidae (Mezirinae, Calisiinae, Aradinae), and it was found that codon usage preferences appeared to be less affected by base mutation and more by natural selection. The Pi and Ka/Ks values indicated that cox1 was the most conserved gene in the mitochondrial genome of Aradidae, while atp8 and nad6 were rapidly evolved genes. Substitution saturation level analysis showed that the nucleic acid sequence of mitochondrial protein-coding genes in Aradidae did not reach saturation, suggesting the rationality of the phylogenetic analysis data. Bayesian and maximum likelihood methods were used to analyze the phylogeny of 16 species of Hemiptera insects, which supported the monophyly of Aneurinae, Carventinae, and Mezirinae, as well as the monophyly of Yangiella. Based on fossils and previous studies, the differentiation time was inferred, indicating that Yangiella diverged about 57 million years ago.

The complete mitochondrial genome of Brachyrhynchus triangulus Bergroth, 1889 was sequenced and annotated in the present study. It was a typical circular DNA molecule of 15,170 bp, with 37 genes and a control region. The percentages of A, C, G, and T nucleotides in the genome of B. triangulus were 41.1%, 17.4%, 11.9%, and 29.4%, respectively. Thirteen protein-coding genes (PCGs) start with a ATN codon or a TTG codon and terminate with a TAA codon or a TAG codon or a single T residue. With the exception of tRNA^Ser(AGN), each of the 22 tRNA genes had a clover-leaf structure and ranged in length from 62 to 69 bp. The length of lrRNA and srRNA was 1241 bp and 828 bp, respectively. The control region had a length of 708 bp and an A + T content of 74.6%. The sister relationship between B. triangulus and Brachyrhynchus hsiaoi is supported by the phylogenetic tree. Additionally, it proved the sister relationship between Mezirinae and Aneurinae, supporting the classical taxonomy of the Aradidae.

Insect communities serve as vital components of ecosystems and environmental indicators. To assess insect community composition and diversity across Inner Mongolia’s grassland types, a systematic survey was conducted between June and August of 2022–2023 using the sweep net method. A total of 38,200 insects were identified, belonging to 4 orders, 69 families, and 518 species. Herbivorous insects dominated the communities, accounting for 98.66% of the total individual count. Dominant species composition varied among grassland types. Significant differences in alpha diversity were observed across habitats. PCoA spatially delineated distinct community structures. Meadow and typical steppes exhibited similar insect communities, while desert and steppe desert also clustered closely. This reflected the influence of environmental gradients on insect distribution. LEfSe analysis identified specific taxa driving these macro-scale differentiations. This differentiation underscores the necessity of tailored insect management strategies. These findings establish theoretical foundations for insect diversity monitoring and contribute to the sustainable use of grassland resources.

Many species of the family Aradidae (also known as flat bugs) feed on fungal mycelia and fruiting bodies. In order to better understand the morphological adaptation to this unique feeding habit, we examined the microstructure of antennae and mouthparts of an aradid species, Mezira yunnana Hsiao, using scanning electron microscope, and documented the fungal feeding process under laboratory conditions. The antennal sensilla include three subtypes of sensilla trichodea, three subtypes of sensilla basiconica, two subtypes of sensilla chaetica, sensilla campaniformia, and sensilla styloconica. The apex of the second segment of flagellum has a large number of various sensilla forming a sensilla cluster. The labial tip is distally constricted, which is rarely observed in other Pentatomomorpha species. The labial sensilla include three subtypes of sensilla trichodea, three subtypes of sensilla basiconica, and a sensilla campaniformia. The tip of the labium has only three pairs of sensilla basiconica III and small comb-shaped cuticular processes. The external surface of the mandibular apex has 8–10 ridge-like central teeth. A series of key morphological structures associated with mycetophagous feeding habit were identified, which will facilitate future studies on adaptive evolution of species in Pentatomomorpha as well as in other heteropteran lineages.

The following new apterous flat bugs of the subfamily Carventinae (Hemiptera: Heteroptera: Aradidae) from China are described and illustrated: Cathaycoris bibulbosus gen. nov. & sp. nov. from Yunnan Province; Taiwanaptera guangxiana sp. nov. from Guangxi Province and Taiwanaptera montana sp. nov. from Yunnan Province. A key to all known species of Taiwanaptera is provided.