Mitochondrial genome sequencing of Solenocera melantho and phylogenetic analysis of Penaeoidea

To expand the research on molecular identification techniques, germplasm resource evaluation, and systematic evolution in Solenoceridae shrimp, this study utilized second-generation high-throughput sequencing technology to obtain the complete mitochondrial genome of Solenocera melantho. The mitochondrial genes were annotated, and their sequence structure was analyzed. The total length of the S. melantho mitogenome was 15 940 bp, with a base composition of A (35.66%), T (32.00%), G (11.14%), and C (21.20%); the A+T content was 67.66%, indicating a pronounced AT bias. The S. melantho mitogenome encodes a total of 37 genes, including 13 protein-coding genes (PCGs), 22 tRNAs, and 2 rRNAs. Among them, 14 genes were located on the negative strand, while 23 genes were located on the positive strand, showing similarity to other Solenoceridae mitogenomes. Most of the PCGs started with typical initiation codons ATG and ATT, but ACG for cox1, ATC for atp8, and ATA for nad5. The termination codons for cox1, cox2, cox3, nad3, and nad5 were incomplete codons, all being T--, while cob terminated with the codon TAG, and all the other PCGs used TAA as the termination codon. trnS1 lacked the DHU arm, and trnY lacked the acceptor stem, while the remaining 20 tRNAs had the typical cloverleaf structure. Leu and Ser were the two most commonly used amino acids, and GGA, UUA, and CGA were the three most commonly used codons. 10 representative species were selected from 5 families under Penaeoidea for selection pressure analysis, revealing that all PCGs in Penaeoidea experienced purifying selection during evolution. Additionally, a phylogenetic tree was constructed by combining the 13 PCGs from the complete mitogenomes of 32 species from the 5 families under Penaeoidea. The results supported the monophyly of Solenoceridae, and S. melantho was found to be most closely related to Solenocera crassicornis. This study filled the gap in the molecular biology of S. melantho, clarified its systematic evolutionary position, explored the gene rearrangement characteristics among species, and provided more references for the study of interspecific evolution in Penaeoidea through the construction of a phylogenetic tree.