Abstract: 【Aim】To sequence and analyze the complete mitochondrial genomes of two palm bugs, Thaumastocoris peregrinus and Onymocoris hackeri, and analyze the phylogenetic placement of Thaumastocoridae within Cimicomorpha. 【Methods】The sequences of the complete mitochondrial genomes and nuclear genes (18S rDNA gene and 28S rDNA gene) of T. peregrinus and O. hackeri in Thaumastocoridae were obtained by high-throughput sequencing. The mitochondrial genomes were annotated and compared. The sequences of mitochondrial genomes and nuclear genes (18S rDNA gene and 28S rDNA gene) of nine species of Heteroptera including Nepomorpha, Leptopodomorpha and Pentatomomorpha from GenBank were selected as outgroups and the sequences of the mitochondrial genomes and nuclear genes (18S rDNA gene and 28S rDNA gene) of 24 species of seven families from Cimicomorpha and two species from Thaumastocoridae were selected as ingroups. The phylogenetic trees were constructed using maximum likelihood (ML) and Bayesian inference (BI) methods based on the sequences of 13 protein coding genes, 18S rDNA gene and 28S rDNA gene. 【Results】 The complete mitochondrial genomes of T. peregrinus and O. hackeri were 15 399 and 15 490 bp in length, respectively, including 13 protein-coding genes, 22 tRNA genes, two rRNA genes and one control region. There was an obvious AT preference in nucleotide composition and no gene rearrangement was found. All of the 22 tRNA genes except tRNA-Ser (GCU) can be folded into a typical clover-leaf secondary structure. Tandem repeat region and stem-loop were found in the control region. The phylogenetic relationship based on maximum likelihood and Bayesian inference methods was recovered as (Reduvioidea+((Cimicoidea+(Velocipedoidea+Nabioidea))+Miroidea)). Thaumastocoridae was located within Miroidea, forming a topology of (Thaumastocoridae+(Miridae+Tingidae)). 【Conclusion】 In this study two complete mitochondrial genomes of Thaumastocoridae were sequenced and analyzed, and the phylogenetic position of Thaumastocoridae within Cimicomorpha was explored. The molecular data of Thaumastocoridae were supplemented, which further enhanced the understanding of the phylogeny of Cimicomorpha and mitochondrial genome evolution.

Key words: Hemiptera, Thaumastocoridae, mitochondrial genome, rRNA, phylogeny