Mitogenomic analysis and phylogenetic implications for the Deltocephalinae (Hemiptera: Cicadellidae)

Deltocephalinae (Hemiptera: Cicadellidae) is the largest subfamily within the leafhopper family Cicadellidae and has an almost worldwide distribution. However, the classification and phylogenetic relationships of Deltocephalinae have not yet been fully resolved. In this study, we sequenced the complete mitogenomes of 12 Deltocephalinae species and compared them with the 50 previously reported mitogenomes for this subfamily. Mitogenome size ranged from 14,648 bp in Scaphoideus albovittatus to 16,711 bp in Mukaria splendida. All contained 37 genes and a variable number of non-coding A + T-rich regions. Nucleotide composition analysis showed that the AT content was higher than GC. And while most protein-coding genes use ATN as the start codon and TAA or TAG as the stop codons, some genes use T as a stop codon. The Ka/Ks ratio showed that the cox1 gene has the slowest evolutionary rate, while atp8 is the gene with the fastest evolutionary rate. These new analyses confirm that Deltocephalinae mitochondrial genomes are highly conservative in overall structure, with only a few rare rearrangements of tRNAs, primarily concentrated in the trnW-trnC-trnY and trnA-trnR-trnN-trnS1-trnE-trnF gene clusters. Deltocephalinae mitochondrial genomes exhibit gene overlaps with three stable regions: trnW and trnC, atp6 and atp8, nad4 and nad4l. The overlapping sequences are typically AAGTCTTA, ATGATAA and TTATCAT. Phylogenetic analyses by maximum likelihood and Bayesian inference were conducted based on five datasets including either amino acid sequences alone or nucleotide sequences from different combinations of protein coding and ribosomal RNA genes, with or without third codon positions (AA, PCG12, PCG12R, PCG123 and PCG123R). Phylogenies obtained from different analyses consistently supported the monophyly of Deltocephalinae and showed high congruence within the subfamily, with few short, deep internal branches unstable among analyses. Included members of the following tribes were consistently monophyletic: Athysanini, Chiasmini, Deltocephalini, Drabescini, Macrostelini, Paralimnini, Penthimiini, Scaphoideini and Stenometopiini. Consistent with other recent analyses, Fieberiellini, Goniagnathini and Penthimiini are early diverging lineages within Deltocephalinae. Overall, our results indicate that complete mitogenome sequences provide robust data for phylogenetic reconstruction.