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The pulmonate snail Melampus sincaporensis L. Pfeiffer, 1855 (Gastropoda: Ellobiidae) lives in extreme environments such as salt marshes with limited oxygen. Here, we characterized the complete mitochondrial genome of M. sincaporensis from South Korea. It is 14,962 bp in length and includes 13 protein-coding genes (PCGs), two genes, 21 tRNA genes lacking one tRNA-Ser, and two A + T rich regions. Among these 36 genes, 24 were encoded on the heavy strand and 12 on the light strand. A maximum likelihood tree constructed using nucleotide sequences of the 13 PCGs did not support the monophyly of Ellobiidae. This study could provide useful information for exploring phylogenetic relationships among ellobiids and their related species.

The chiton (Polyplacophora) occupies a significant position in molluscan evolutionary history as one of the most primitive groups within the phylum Mollusca. Acanthochitona defilippii (Tapparone-Canefri 1874) (Chitonida: Acanthochitonidae) is a commonly found intertidal chiton species in South Korea. In this study, we characterized the complete mitochondrial genome of A. defilippii (14,999 bp long), comprising 13 protein-coding genes (PCGs), 22 transfer RNA genes, two ribosomal RNA genes, and an A + T rich region (166 bp). The base composition is as follows: 31.82% for A, 11.63% for C, 16.69% for G, and 39.86% for T. We reconstructed a maximum likelihood (ML) tree to elucidate phylogenetic relationships among the eight chitonid families using the nucleotide sequences of all PCGs. The ML tree revealed that A. defilippii clustered with Acanthochitona avicula (BP 100) within the family Acanthochitonidae. Acanthochitonidae formed a sister group with Mopaliidae. The results could provide a valuable understanding the phylogenetic relationships of chitonid species.

The ground beetle Synuchus nitidus (Motschulsky, 1861) (Carabidae: Harpalinae: Sphodrini) is one of the most common species in the forests of South Korea, which has the potential to be utilized as an environmental indicator. Here, we characterized the complete mitochondrial genome (mitogenome) of S. nitidus, which is the first in the harpaline tribe Sphodrini. Its genome is 16,392 bp in length and composed of 13 protein-coding genes (PCGs), 22 tRNA genes, two rRNA genes, and an A + T rich region. In addition, we reconstructed a maximum likelihood tree to elucidate the phylogenetic position of Sphodrini among the seven harpaline tribes using nucleotide sequences of the 13 PCGs. The ML tree supported a monophyletic clade of the subfamily Harpalinae and showed a close relationship between Sphodrini and Lebinii with a low bootstrap value. The complete mitogenome of S. nitidus could be helpful for molecular species identification and exploring phylogenetic relationships among carabids.

The worm snail Thylacodes adamsii (Mörch, 1859) (Littorinimorpha: Vermetidae) is a sessile gastropod that mainly inhabits rocky shores along the warm temperate to tropical ocean. Herein, the complete mitochondrial genome (mitogenome) of T. adamsii from South Korea was characterized. The genome is 14,913 bp in length and contains 13 protein-coding genes (PCGs), 22 tRNA genes, and 2 rRNA genes. The genome organization and base composition of T. adamsii are similar to those of other vermetids. A phylogenetic tree was reconstructed using maximum likelihood based on the nucleotide sequences of the 13 PCGs; this tree supported the monophyly of Vermetidae. The complete mitogenome of T. adamsii can assist with molecular species identification and vermetid phylogenetic research in the future.

The mitochondrial genome of a golden orb-web spider Trichonephila clavata (L. Koch, 1878) from South Korea is determined and characterized in detail, which is the second mitochondrial genome reported from this species: the first was published from the Chinese sample by Pan et al. (). It was 14,436 bp in length being composed of 13 protein-coding genes (PCGs), 22 transfer RNA genes, two ribosomal RNA genes, and one control region (CR). It has a base composition of 35.99% for ‘A,’ 14.88% for ‘G,’ 9.09% for ‘C,’ and 40.04% for ‘T.’ Comparing the South Korean and Chinese mitochondrial genomes, we observed 8% nucleotide sequence differences between their CRs, caused by the different numbers and sorts of possessed tandem repeats, suggesting a promising molecular marker to distinguish South Korean individuals from Chinese ones. The phylogenetic trees using the maximum likelihood (ML) method were reconstructed with nucleotides (without 3rd codon position) and amino acids from 13 PCGs, respectively, which consistently confirmed that T. clavata (Subfamily Nephilinae) from South Korea and China are clustered together, distinctly separated from the other subfamily Araneinae in the monophyletic family Araneidae.

We present the complete mitochondrial genome of a Malaria vector Mosquito Anopheles sinensis Wiedemann, 1828 from South Korea. The mitochondrial genome is about 15,421 bp long and contains 13 protein-coding genes (PCGs), 22 tRNA genes, two rRNA genes, and an A-T rich region. The present data were compared with those from China with respect to PCG sequence differences, tRNA structure, gene order, and control region (CR) structure. An. sinensis mitochondrial genomes from northeast Asia share identical gene composition and gene order. In contrast, they have distinct differences in the CR within the range 8.75% (51/583 bp) to 9.95% (58/583 bp). The phylogenetic analysis showed that An. sinensis from South Korea was clustered together with those from China, but there existed distinct genetic distance between the two. Likewise, mitochondrial genome sequences from other Anopheles species were employed to infer phylogenetic relationships among the members of the genus Anopheles. This study further promotes the enrichment of An. sinensis mitochondrial genome data, providing useful information for their mitochondrial genetic differences along with geographical distances in northeast Asia.

The mitochondrial genome of the Endangered freshwater snail Koreoleptoxis nodifila (Caenogastropoda: Semisulcospiridae) from South Korea is determined and characterized in detail. It is 15,737 bp in length being composed of 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), two ribosomal RNA genes (rRNAs), and one control region. It has a base composition of 31.23% for A, 16.29% for G, 17.84% for C, and 34.64% for T. The phylogenetic trees reconstructed based on the maximum-likelihood (ML) method and Bayesian inference (BI) confirmed that K. nodifila belongs to the Semisulcospiridae clade in the monophyletic caeonogastropod superfamily Cerithioidea.

The complete mitochondrial genome of an endangered triton snail Charonia lampas (Littorinimorpha: Charoniidae) from South Korea was determined with the size of 15,330 bp, which contained 13 protein-coding genes, 22 tRNAs, and two rRNAs. The overall features of the mitochondrial genome are similar to those of typical gastropod mitochondrial genomes, except for the absence of a control region (CR): a conserved gene order, a high A + T content (67.45% for C. lampas), preference for AT-rich codons, etc. It is the second mitochondrial genome reported from this species after Cho et al. (2017), and there is ca. 98% sequence similarity between those of the species. According to the maximum-likelihood tree, C. lampas placed within the monophyletic Tonnoidea, forming a monoclade with Cypraeoidea and Stromboidea within Littorinimorpha. Interestingly, we confirmed that Vermetoidea is placed at the basal position of the monophyletic Littorinimorpha.

A giant water bug Lethocerus deyrollei (Hemiptera: Belostomatidae) is a large, predatory, and nocturnal hemipteran insect, which has been considered threatened and thus enrolled as an endangered species in South Korea and Japan. Here, we characterized the complete mitochondrial genome of L. deyrollei, which has a circular form with 19,295 bp in length, which is the longest when compared to those of the 111 hemipteran species reported so far. Its longest genome size is due to the extremely extended CR (4686 bp), which is much longer than those of China and Japan. It consisted of a total of 37 genes (13 PCGs, 22 tRNA genes, and two rRNA genes) and one control region (CR). The genome composition and gene order were identical to those previously reported from the same species of China and Japan with over 99.7% sequence similarities except for CR and trnI. The nucleotide composition was highly A + T biased, accounting for 71% of the whole mitochondrial genome, as in other species of Nepoidea. Based on the aa sequences of 13 PCGs, we reconstructed a maximum likelihood tree, which indicated that the three mitochondrial genomes of L. deyrollei from South Korea, China, and Japan are grouped, and also Lethocerus, Belostomatidae, Nepoidea, Nepomorpha, Heteroptra are strong monophyletic groups, respectively.

The complete mitochondrial genome of a two-spotted cricket Gryllus bimaculatus (Orthoptera: Gryllidae) from South Korea is determined and characterized in this study. The circular genome is 16,075 bp long, which consists of 13 protein-coding genes (PCGs), 2 ribosomal RNA genes, 22 transfer RNA genes, and an A + T−rich region. It has a base composition of A (40.35%), G (9.09%), C (16.80%), and T (33.76%). The gene order is identical to the ancestral gene arrangement pattern generally shown in arthropods, with the exception of an inversion of trnN-trnS1-trnE into trnE-trnS1-trnN. The maximum likelihood (ML) tree supports that G. bimaculatus is a distinct member of the monophyletic family Gryllidae.

The complete mitochondrial genome of Protaetia brevitarsis, an important Scarabaeidae insect that is distributed across most Asian countries, was characterized using long template PCR methods. It was 17,783 bp in length being composed of 13 protein coding genes (PCGs), 22 transfer RNA genes (tRNAs), two ribosomal RNA genes (rRNAs) and a non-coding region. The phylogenetic tree reconstructed based on the maximum likelihood (ML) method confirmed that P. brevitarsis was placed within the clade of Scarabaeidae and Polyphaga species forming a complete monophyly.

A hen harrier Circus cyaneus (Accipitriformes: Accipitridae), a migrant raptor having a wide breeding range from Europe to Northeast Asia, migrates to more southerly areas (Southern Europe, China, Korea and Japan) in winter. In this study, the complete mitochondrial genome of C. cyaneus was completely sequenced and characterized. It was 20,173 bp in length being composed of 13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes and two control regions. It has a base composition of A (32.2%), G (12.6%), C (30.5%) and T (24.7%). The phylogenetic tree reconstructed based on the maximum likelihood (ML) method confirms that C. cyaneus places within the clade of the family Accipitridae in the monophyletic avian order Accipitriformes.

Plumarella spinosa (Anthozoa: Octocorallia: Primnoidae) is an endangered marine soft coral species discovered on a 50–100 m deep reefs in South Korea. We analyzed the mitochondrial genome sequence of this species. The genome size was 19,037 bp in length consisting of 14 protein coding genes (PCGs), two rRNA genes and a tRNA gene. Our phylogenetic analysis for this species with 33 Octocorallia species reconstructed based on the nucleotide sequences of 14 PCGs showed that P. spinosa was placed as a sister to Narella hawainensis and Primnoidae formed a monophyletic group.

The complete mitochondrial genome sequence from the Asian crested ibis, Nipponia nippon (Aves, Pelecaniformes, Threskiornithidae), was determined and characterized in detail. This mitochondrial genome is 16,813 bp long, and consists of 13 PCGs, 22 tRNAs, and 2 rRNAs. The nucleotide composition is slightly biased with A + T contents of 53.79% (A, T, C, and G was 30.37%, 23.42%, 31.99%, and 14.22%, respectively). 11 PCGs are initiated by ATN codons, except for cox1 and cox2 with GTG instead. The phylogenetic relationships based on the maximum-likelihood and Bayesian methods showed that the placement of N. nippon within the order Pelecaniformes, with forming the monoclade of the family Threskiornithidae.

The circular F-type mitochondrial genome (15,761 bp) was completely sequenced for a Korean freshwater mussel Nodularia douglasiae (synonym Unio douglasiae; Unionidae, Unionida, Bivalvia). It contains 13 PCGs, two rRNA genes, and 22 tRNA genes, as generally shown in metazoan mitochondrial genomes. Its gene order is identical to that of F-type mitochondrial genomes observed in other freshwater mussels. With nucleotide and amino acid sequences of the complete F-type mitochondrial genomes obtained from 38 unionid species reported so far, phylogenetic analyses were done and discussed. The present study may give valuable helps to explore genetic diversity and population structures of other freshwater mussels as well as N. douglasiae.

Parasesarma tripectinis is known as an intertidal crab and inhabits Asian region. This crab has larval release at semilunar rhythm. Here, we report the complete sequence of the mitochondrial genome (mitogenome), which is composed of 15,612 base pair (bp) encoding 13 protein-coding genes, 22 transfer RNAs, 2 ribosomal RNAs, and an A + T rich region. The nucleotide composition of P. tripectinis was G + C: 25.8%, A + T: 74.2%, with a strong AT bias. Phylogenetic analysis using whole mitogenome figured out that P. tripectinis was closely related to Sesarma neglectum which belongs to the same family Sesarmidae.