Characterization of the mitochondrial genome of Arge bella Wei & Du sp. nov. (Hymenoptera: Argidae)

Abstract

We describe Arge bella Wei & Du sp. nov., a large and beautiful species of Argidae from south China, and report its mitochondrial genome based on high-throughput sequencing data. We present the gene order, nucleotide composition of protein-coding genes (PCGs), and the secondary structures of RNA genes. The nearly complete mitochondrial genome of A. bella has a length of 15,576 bp and a typical set of 37 genes (22 tRNAs, 13 PCGs, and 2 rRNAs). Three tRNAs are rearranged in the A. bella mitochondrial genome as compared to the ancestral type in insects: trnM and trnQ are shuffled, while trnW is translocated from the trnW-trnC-trnY cluster to a location downstream of trnI. All PCGs are initiated by ATN codons, and terminated with TAA, TA or T as stop codons. All tRNAs have a typical cloverleaf secondary structure, except for trnS1. H821 of rrnS and H976 of rrnL are redundant. A phylogenetic analysis based on mitochondrial genome sequences of A. bella, 21 other symphytan species, two apocritan representatives, and four outgroup taxa supports the placement of Argidae as sister to the Pergidae within the symphytan superfamily Tenthredinoidea.

Keywords: Arge bella; Cladistic analysis; Mitochondrial genome; New species; Secondary structure; Taxonomy.

Figure 1. Arge bella Wei & Du sp. nov. Adult female, dorsal view.

Scale bars = 1 mm.

Figure 2. Arge bella.

Figures (A-M). Arge bella Wei & Du sp. nov. (A) Head of female, front view; (B) abdomen, dorsal view; (C) mesopleuron of female, lateral view; (D) head of female, dorsal view; (E) sheath of female, lateral view; (F) sheath of female, ventral view; (G) basal serrulae of lancet; (H) Antenna of female; (I) head of female, lateral view; (J) tibia of hind leg; (K) lancet; (L) lance; (M) sheath of female, dorsal view.

Figure 3. Mitochondrial genome organisation of A. bella.

Mitochondrial genome organisation of insects in general (above) and A. bella (below). Genes are transcribed from left to right, except for those underlined. PCGs are marked by white, the A + T rich region by grey, rRNA genes by red, and tRNA genes by yellow and single-letter amino acid codes. Gene rearrangements are shown with connecting lines that indicate the translocation of trnW from the trnW-trnC-trnY cluster to a position downstream of trnI and the swapped position of trnM and trnQ.

Figure 4. A. bella tRNAs.

Predicted secondary structures of the 22 tRNA genes of A. bella (A–V): (A) trnA; (B) trnR; (C) trnN; (D) trnD; (E) trnC; (F) trnQ; (G) trnE; (H) trnG; (I) trnH; (J) trnI; (K) trnL1 (CUN); (L) trnL2 (UUR); (M) trnK; (N) trnM; (O) trnF; (P) trnP; (Q) trnS1 (AGN); (R) trnS2 (UCN); (S) trnT; (T) trnW; (U) trnY; (V) trnV. Dashes indicate Watson–Crick base pairing and dots indicate G–U base pairing.

Figure 5. A. bella rrnS.

The predicted secondary structure of rrnS in the A. bella mitochondrial genome. The numbering of helices follows Gillespie et al. (2006), and the domain names follows Niehuis, Naumann & Misof (2006); roman numbers refer to domain names.

Figure 6. A. bella rrnL.

Predicted secondary structure of rrnL in the A. bella mitochondrial genome. The numbering of helices and domain names follows Gillespie et al. (2006); roman numbers refer to domain names.

Figure 7. Phylogenetic tree of Symphyta and selected apocritan and outgroup taxa, based on a Maximum-likelihood analysis of sequence data from 13 PCGs and 2 rRNA genes.

The numbers at the branches represent Maximum-likelihood bootstrap values/Bayesian posterior probabilities. 100/1.00 is denoted by an asterisk. The scale bar indicates the number of substitutions per site.