# New Mitogenomes from the Genus Ablabesmyia (Diptera: Chironomidae, Tanypodiinae): Characterization and Phylogenetic Implications

## TL;DR

This paper reports the first mitochondrial genomes of the genus Ablabesmyia, offering new insights into their evolution and classification.

## Contribution

The study provides the first characterization of Ablabesmyia mitogenomes and expands the chironomid mitochondrial genome database.

## Key findings

- All newly assembled mitogenomes showed a cytosine bias and adenine/thymine abundance.
- The evolutionary rates of protein-coding genes were determined, with ND2 being the fastest evolving.
- The structural features of the mitogenomes align with those of other Chironomidae species.

## Abstract

Chironomidae, a highly diverse family of freshwater flies, possess an unparalleled ability to thrive in a vast array of aquatic environments. The Chironomidae family is currently divided into 11 subfamilies, with the subfamily Tanypodinae comprising nearly 60 genera and over 600 species worldwide, and the genus Ablabesmyia being one of the largest within the Pentaneurini tribe. The mitochondrial genome of the genus Ablabesmyia has not yet been reported. We have undertaken the sequencing, assembly, and annotation of the mitochondrial genomes for a selection of species within the genus Ablabesmyia, which includes eight distinct species. Our comprehensive examination, which includes a total of 17 mitochondrial genomes, offers unprecedented insights into the evolutionary narratives of these taxa, contributing significantly to the field of entomology and evolutionary biology.

(1) Background: The insect mitogenome encodes essential genetic components and serves as an effective marker for molecular identification and phylogenetic analysis in insects due to its small size, maternal inheritance, and rapid evolution. The morphological identification of Ablabesmyia is challenging, particularly for non-experts. Thus, there is an increasing need for molecular data to improve classification accuracy and phylogenetic analysis. (2) Methods: Our analysis encompassed eight species of Ablabesmyia, a single species of Conchapelopia, one species of Denopelopia, and one species of Thienemannimyia, all originating from China. We then performed a comprehensive analysis of the nucleotide composition, sequence length, and evolutionary rate. (3) Results: All newly assembled mitogenomes displayed a negative GC-skew, indicating a cytosine bias, while most exhibited a positive AT-skew, reflecting an adenine and thymine abundance. All thirteen protein-coding genes (PCGs) featured the conventional start codon ATN, aligning closely with the typical mitochondrial start codon observed in insects. The evolutionary rates of these PCGs can be ordered as follows: ND2 > ATP8 > ND6 > ND4 > ND5 > ND3 > ND4L > ND1 > CYTB > COIII > ATP6 > COII > COI. (4) Conclusions: These newly sequenced mitogenomes exhibit structural features and nucleotide compositions that closely align with those of previously reported Chironomidae species, marking a significant expansion of the chironomid mitogenome database.