Comparative Mitogenomic Analysis of Two Longhorn Beetles (Coleoptera: Cerambycidae: Lamiinae) with Preliminary Investigation into Phylogenetic Relationships of Tribes of Lamiinae

The Phylogenetic Relationship of Lamiinae (Coleoptera: Cerambycidae) Using Mitochondrial Genomes

Lamiinae is the largest subfamily of the Cerambycidae (longhorn beetles), with approximately 21,863 described species. Previous phylogenetic studies of Lamiinae showed that this subfamily was monophyletic, but the relationship between the tribes of Lamiinae is still controversial. Partial molecular data and species morphological characteristics are not sufficient to resolve species phylogenetic studies perfectly. At the same time, the full mitochondrial genome contains more comprehensive genetic data. Benefiting from the development of next-generation sequencing (NGS), mitochondrial genomes can be easily acquired and used as reliable molecular markers to investigate phylogenetic relationships within Cerambycidae. Using NGS technology, we obtained 11 mitochondrial genome sequences of Lamiinae species. Based on this newly generated mitochondrial genome dataset matrix, we reconstructed the phylogeny of Lamiinae. The Bayesian Inference and Maximum Likelihood analyses strongly support the monophyly of four tribes (Lamiini, Batocerini, Mesosini, and Saperdini), whereas the tribe Acanthocinini was identified as paraphyletic. Other mitochondrial structural features were also observed: the start codon in the nad1 gene of all 11 mitochondrial genomes is TTG; 17-22 bp intergenic spacers (IGS) with a 'TACTA' motif were found between trnS2 and nad1. Moreover, two long IGS were found in Mesosa myops and Batocera sp. Tandem repeats were found in the IGS of Batocera sp.

Comparative mitochondrial genomic analysis provides new insights into the evolution of the subfamily Lamiinae (Coleoptera: Cerambycidae)

The genus Monochamus within the subfamily Lamiinae is the main vector of Bursaphelenchus xylophilus, which causes pine wilt disease and induces substantial economic and ecological losses. Only three complete mitochondrial genomes of the genus Monochamus have been sequenced to date, and no comparative mitochondrial genomic studies of Lamiinae have been conducted. Here, the mitochondrial genomes of two Monochamus species, M. saltuarius and M. urussovi, were newly sequenced and annotated. The composition and order of genes in the mitochondrial genomes of Monochamus species are conserved. All transfer RNAs exhibit the typical clover-leaf secondary structure, with the exception of trnS1. Similar to other longhorn beetles, Lamiinae mitochondrial genomes have an A + T bias. All 13 protein-coding genes have experienced purifying selection, and tandem repeat sequences are abundant in the A + T-rich region. Phylogenetic analyses revealed congruent topologies among trees inferred from the five datasets, with the monophyly of Acanthocinini, Agapanthiini, Batocerini, Dorcaschematini, Pteropliini, and Saperdini receiving high support. The findings of this study enhance our understanding of mitochondrial genome evolution and will provide a basis for future studies of population genetics and phylogenetic investigations in this group.

Taxonomic notes about the genus Nephelotus Pascoe, 1866 (Coleoptera, Cerambycidae, Lamiinae)

Paranhammus Breuning, 1944 and Mimonephelotes Breuning, 1970 (both monotypic genera) are considered junior synonyms of Nephelotus Pascoe, 1866. Mimanhammus Breuning, 1971 is considered an unnecessary replacement name for Mimonephelotes, despite the similarity to Mimonephelotus Breuning, 1940. Resultant combinations are Nephelotus enganensis (Breuning, 1970) and Nephelotus marcipor (Newman, 1842). Anhammus luzonicus Breuning, 1982 is considered a junior synonym of N. enganensis.