Complete mitochondrial genome sequence of Bonasa sewerzowi(Galliformes: Phasianidae) and phylogenetic analysis

Bonasa sewerzowi, the smallest and most southerly distributed grouse species in the world, is a bird endemic to China. The population of B. sewerzowi had shown a declining trend, which made it to be the endangered species in the China Red Data Book and Category I of nationally protected animals. So far, however, most studies about this species were mainly focused on the morphological and ecological aspects. In order to further study the feature of B. sewerzowi, the complete mitochondrial genome(mitogenome) of B. sewerzowi was sequenced by Illumina Hiseq 2000 high-throughput sequencing. Then, we focused on comparative genomics of two Bonasa species to find their characteristics. Finally, phylogenetic position of Bonasa was made based on the mitogenome dataset. Our results revealed that:(1) the mitogenome of B. sewerzowi, consisting of 16 658 bp, displayed typical genome organization and gene order found in other previously determined Galliformes mitogenomes;(2) the structure and composition of mitogenomes were similar between B. sewerzowi and B. bonasia;(3) the monophyly of Bonasa was well supported, which had a closer phylogenetic relationship with Meleagris gallopavo.     

Next‐generation sequencing workflow for assembly of nonmodel mitogenomes exemplified with North Pacific albatrosses (Phoebastria spp.)

Use of complete mitochondrial genomes (mitogenomes) can greatly increase the resolution achievable in phylogeographic and historical demographic studies. Using next‐generation sequencing methods, it is now feasible to efficiently sequence mitogenomes of large numbers of individuals once a reference mitogenome is available. However, assembling the initial mitogenomes of nonmodel organisms can present challenges, for example, in birds, where mtDNA is often subject to gene rearrangements and duplications. We developed a workflow based on Illumina paired‐end, whole‐genome shotgun sequencing, which we used to generate complete 19‐kilobase mitogenomes for each of three species of North Pacific albatross, a group of birds known to carry a tandem duplication. Although this duplication had been described previously, our procedure did not depend on this prior knowledge, nor did it require a closely related reference mitogenome (e.g. a mammalian mitogenome was sufficient). We employed an iterative process including de novo assembly, reference‐guided assembly and gap closing, which enabled us to detect duplications, determine gene order and identify sequence for primer positioning to resolve any mitogenome ambiguity (via minimal targeted Sanger sequencing). We present full mtDNA annotations, including 22 tRNAs, 2 rRNAs, 13 protein‐coding genes, a control region and a duplicated feature for all three species. Pairwise comparisons supported previous hypotheses regarding the phylogenetic relationships within this group and occurrence of a shared tandem duplication. The resulting mitogenome sequences will enable rapid, high‐throughput NGS mitogenome sequencing of North Pacific albatrosses via direct reference‐guided assembly. Moreover, our approach to assembling mitogenomes should be applicable to any taxon.     

The complete mitochondrial genome of Eterusia aedea (Lepidoptera,Zygaenidae) and comparison with other zygaenid moths

Zygaenidae comprises >1036 species, including many folivorous pests in agriculture. In the present study, the complete mitochondrial genome (mitogenome) of a major pest of tea trees, Eterusia aedea was determined. The 15,196-bp circular genome contained the common set of 37 mitochondrial genes (including 13 protein-coding genes, two rRNA genes, and 22 tRNA genes) and exhibited the similar genomic features to reported Zygaenidae mitogenome. Comparative analyses of Zygaenidae mitogenomes showed a typical evolutionary trend of lepidopteran mitogenomes. In addition, we also investigated the gene order of lepidopteran mitogenomes and proposed that the novel gene order trnA-trnR-trnN-trnE-trnS-trnF from Zygaenidae and Gelechiidae and most other gene rearrangements of this tRNA cluster evolved independently. Finally, the mitogenomic phylogeny of Lepidoptera was reconstructed based on multiple mitochondrial datasets. And all the phylogenetic results revealed the sister relationships of Cossoidea and Zygaenoidea with both BI and ML methods, which is the first stable mitogenomic evidence for this clade.     

Two mitogenomes in Gruiformes (<Emphasis Type="Italic">Amaurornis akool</Emphasis>/<Emphasis Type="Italic">A. phoenicurus</Emphasis>) and the phylogenetic placement of Rallidae

Rallidae, with 34 genera including 142 species, is the largest family in the Gruiformes, the phylogenetic placement of this family was still in debate. The complete mitochondrial genomes (mitogenomes), with many advantageous characters, have become popular markers in phylogenetic analyses. We sequenced the mitogenomes of brown crake (Amaurornis akool) and white-breasted waterhen (Amaurornis phoenicurus), analyzed the genomic characters of mitogenomes in Rallidae, and explored the phylogenetic relationships between Rallidae and other four families in Gruiformes based on mitogenome sequences of 32 species with Bayesian method. The mitogenome of A. akool/A. phoenicurus was 16,950/17,213 bp in length, and contained 37 genes typical to avian mitogenomes and one control region, respectively. The genomic characters of mitogenomes in Rallidae were similar. The phylogenetic results indicated that, among five families, Rallidae had closest relationship with Heliornithidae, which formed a sister taxa to Gruidae, while Rhynochetidae located in the basal lineage. Within Rallidae, Rallina was ancestral clade. Gallirallus & Rallus and Aramides were closely related, Gallicrex & Amaurornis and Fulica & Gallinula had close relationships, and these two taxa formed a sister clade to Porphyrio & Coturnicops. Our phylogenetic analyses provided solid evidence for the phylogenetic placement of Rallidae and the evolutionary relationships among different genus within this family. In addition, the mitogenome data presented here provide useful information for further molecular systematic investigations on Gruiformes as well as conservation biology research of these species.     

The complete mitogenome of Rhodeus uyekii (Cypriniformes, Cyprinidae).

The complete nucleotide sequence of the mitochondrial genome from the R. uyekii with a total size of 16,817 bp has been determined by long PCR technology. Mitogenome of R. uyekii encoding 13 putative proteins, two ribosomal RNAs and 22 tRNAs shows typical teleost mitogenome structure. Nucleotide composition, amino acid composition and codon usage are in the range of values estimated from other teleost mitogenomes. In the AT rich region of R. uyekii, several conserved blocks which are identified from vertebrates are observed in the genome. R. uyekii, the Korean endemic species, belongs to cyprinid fish from which the information of nine mitogenomes is available. To understand the phylogenetic relationships of Cypriniformes from the known mitogenome information, we analysed Cypriniformes mitogenome based on protein coding gene sequences. In spite of more resolved picture of phylogenetic interrelationships in cyprinid fish in this study, the further study with comprehensive taxon sampling for mitogenome information is strongly needed.     

Complete mitochondrial genome of the Iberian Mole <Emphasis Type="Italic">Talpa occidentalis</Emphasis> (Talpidae,Insectivora) and comparison with <Emphasis Type="Italic">Talpa europaea</Emphasis>

The complete mitogenome of Talpa occidentalis, the Iberian mole, was sequenced using a combination of the Illumina and Sanger methods. The 16,962 bp genome obtained contains 13 protein-coding genes, 22 transfer RNAs, 2 ribosomal RNAs, and a control region. Thirty-seven identical repetitions of a 10-nucleotide (CACACGTACG) repeat element were identified in the non-coding control region (D-loop). The number, order, and orientation of the mitochondrial genes are the same as in T. europaea, the only mitogenome published so far for this genus. These two mitogenomes differ only at the repeat element included in the control region. The phylogeny obtained for the Talpidae species using the protein-coding genes of these mitogenomes agrees with the current classification of this family.     

The complete mitochondrial genome of Parasesarma pictum (Brachyura: Grapsoidea: Sesarmidae) and comparison with other Brachyuran crabs

Mitochondrial DNA (mtDNA) is an extrachromosomal genome which can provide important information for evolution and phylogenetic analysis. In this study, we assembled a complete mitogenome of a crab Parasesarma pictum (Brachyura: Grapsoidea: Sesarmidae) from next generation sequencing reads at the first time. P. pictum is a mudflat crab, belonging to the Sesarmidae family (subfamily Sesarminae), which is perched on East Asia. The 15,716 bp mitogenome covers 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), 2 ribosomal RNA genes (rRNAs), and one control region (CR). The control region spanns 420 bp. The genome composition was highly A+T biased 75.60% and showed negative AT-skew (−0.03) and negative GC-skew (−0.47). Compared with the ancestor of Brachyura, the gene order of Sesarmidae has several differences and the gene order of P. pictum is typical for mitogenomes of Sesarmidae. Phylogenetic tree based on nucleotide sequences of mitochondrial 13 PCGs using BI and ML determined that P. pictum has a sister group relationship with Parasesarma tripectinis and belongs to Sesarmidae.     

Mitochondrial genome of <Emphasis Type="Italic">Pteronotus personatus</Emphasis> (Chiroptera: Mormoopidae): comparison with selected bats and phylogenetic considerations

We described the complete mitochondrial genome (mitogenome) of the Wagner’s mustached bat, Pteronotus personatus, a species belonging to the family Mormoopidae, and compared it with other published mitogenomes of bats (Chiroptera). The mitogenome of P. personatus was 16,570 bp long and contained a typically conserved structure including 13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes, and one control region (D-loop). Most of the genes were encoded on the H-strand, except for eight tRNA and the ND6 genes. The order of protein-coding and rRNA genes was highly conserved in all mitogenomes. All protein-coding genes started with an ATG codon, except for ND2, ND3, and ND5, which initiated with ATA, and terminated with the typical stop codon TAA/TAG or the codon AGA. Phylogenetic trees constructed using Maximum Parsimony, Maximum Likelihood, and Bayesian inference methods showed an identical topology and indicated the monophyly of different families of bats (Mormoopidae, Phyllostomidae, Vespertilionidae, Rhinolophidae, and Pteropopidae) and the existence of two major clades corresponding to the suborders Yangochiroptera and Yinpterochiroptera. The mitogenome sequence provided here will be useful for further phylogenetic analyses and population genetic studies in mormoopid bats.     

The mitogenomes of three beetles (Coleoptera: Polyphaga: Cucujiformia): New gene rearrangement and phylogeny

The mitochondrial genome (mitogenome) has been extensively used for studying phylogenetic relationships at different taxonomic levels. Several molecular analyses have been performed, but the phylogenetic relationships among infraorders in Polyphaga have not been well resolved. In this work, three nearly complete mitogenomes of Coleoptera, Sitophilus oryzae, Oryzaephilus surinamensis and Callosobruchus chinensis, were determined. The O. surinamensis and S. oryzae mitogenomes harbor gene content typical of other Polyphaga mitogenomes, while a gene rearrangement (trnQ) was found in the C. chinensis mitogenome. The mitogenomes of these three Coleoptera species each consist of approximately 13 protein-coding genes, 22 tRNA genes, two rRNA genes and one A + T-rich region. Phylogenetic analysis within Polyphaga was carried out based on mitochondrial data. The phylogenetic results within Polyphaga support the basal position of Cyphon sp., which belonged to Scirtoidea, Elateriformia. Within Cucujiformia, monophyletic Curculionoidea, Chrysomeloidea and Tenebrionoidea were confirmed.     

Round and pointed-head grenadier fishes (Actinopterygii: Gadiformes) represent a single sister group: evidence from the complete mitochondrial genome sequences

The gene order of mitochondrial genomes (mitogenomes) has been employed as a useful phylogenetic marker in various metazoan animals, because it may represent uniquely derived characters shared by members of monophyletic groups. During the course of molecular phylogenetic studies of the order Gadiformes (cods and their relatives) based on whole mitogenome sequences, we found that two deep-sea grenadiers (Squalogadus modificatus and Trachyrincus murrayi: family Macrouridae) revealed a unusually identical gene order (translocation of the tRNA(Leu (UUR))). Both are members of the same family, although their external morphologies differed so greatly (e.g., round vs. pointed head) that they have been placed in different subfamilies Macrouroidinae and Trachyrincinae, respectively. Additionally, we determined the whole mitogenome sequences of two other species, Bathygadus antrodes and Ventrifossa garmani, representing a total of four subfamilies currently recognized within Macrouridae. The latter two species also exhibited gene rearrangements, resulting in a total of three different patterns of unique gene order being observed in the four subfamilies. Partitioned Bayesian analysis was conducted using available whole mitogenome sequences from five macrourids plus five outgroups. The resultant trees clearly indicated that S. modificatus and T. murrayi formed a monophyletic group, having a sister relationship to other macrourids. Thus, monophyly of the two species with disparate head morphologies was corroborated by two different lines of evidence (nucleotide sequences and gene order). The overall topology of the present tree differed from any of the previously proposed, morphology-based phylogenetic hypotheses.     

Mitogenomes of two neotropical bird species and the multiple independent origin of mitochondrial gene orders in Passeriformes

At least four mitogenome arrangements occur in Passeriformes and differences among them are derived from an initial tandem duplication involving a segment containing the control region (CR), followed by loss or reduction of some parts of this segment. However, it is still unclear how often duplication events have occurred in this bird order. In this study, the mitogenomes from two species of Neotropical passerines (Sicalis olivascens and Lepidocolaptes angustirostris) with different gene arrangements were first determined. We also estimated how often duplication events occurred in Passeriformes and if the two CR copies demonstrate a pattern of concerted evolution in Sylvioidea. One tissue sample for each species was used to obtain the mitogenomes as a byproduct using next generation sequencing. The evolutionary history of mitogenome rearrangements was reconstructed mapping these characters onto a mitogenome Bayesian phylogenetic tree of Passeriformes. Finally, we performed a Bayesian analysis for both CRs from some Sylvioidea species in order to evaluate the evolutionary process involving these two copies. Both mitogenomes described comprise 2 rRNAs, 22 tRNAs, 13 protein-codon genes and the CR. However, S. olivascens has 16,768 bp showing the ancestral avian arrangement, while L. angustirostris has 16,973 bp and the remnant CR2 arrangement. Both species showed the expected gene order compared to their closest relatives. The ancestral state reconstruction suggesting at least six independent duplication events followed by partial deletions or loss of one copy in some lineages. Our results also provide evidence that both CRs in some Sylvioidea species seem to be maintained in an apparently functional state, perhaps by concerted evolution, and that this mechanism may be important for the evolution of the bird mitogenome.     

Massive gene rearrangements of mitochondrial genomes and implications for the phylogeny of Trichoptera (Insecta)

Mitochondrial genomes have been widely used for phylogenetic reconstruction and evolutionary analysis in various groups of Insecta. Gene rearrangements in the mitogenome can be informative characters for phylogenetic reconstruction and adaptive evolution. Trichoptera is one of the most important groups of aquatic insects. Prior to this study, complete mitogenomes from Trichoptera were restricted to eight families, resulting in a biased view of their mitogenome structure and evolution. Here, we assemble new mitogenomes for 66 species by high-throughput sequencing. The mitogenomes of 19 families and 47 genera are documented for the first time. Combined with 16 previously published mitogenomes of Trichoptera, we find 14 kinds of gene rearrangement patterns novel for Trichoptera, including rearrangement of protein-coding genes, tRNAs and control regions. Simultaneously, we provide evidence for the occurrence of tandem duplication and non-random loss events in the mitogenomes of three families. Phylogenetic analyses show that Hydroptilidae was recovered as a sister group to Annulipalpia. The increased nucleotide substitution rate and adaptive evolution may have affected the mitochondrial gene rearrangements in Trichoptera. Our study offers new insights into the mechanisms and patterns of mitogenome rearrangements in Insecta at large and into the usefulness of mitogenomic gene order as a phylogenetic marker within Trichoptera.     

The complete mitogenome assemblies of 10 diploid potato clones reveal recombination and overlapping variants

The potato mitogenome is complex and to understand various biological functions and nuclear–cytoplasmic interactions, it is important to characterize its gene content and structure. In this study, the complete mitogenome sequences of nine diploid potato clones along with a diploid Solanum okadae clone were characterized. Each mitogenome was assembled and annotated from Pacific Biosciences (PacBio) long reads and 10X genomics short reads. The results show that each mitogenome consists of multiple circular molecules with similar structure and gene organization, though two groups (clones 07506-01, DW84-1457, 08675-21 and H412-1 in one group, and clones W5281-2, 12625-02, 12120-03 and 11379-03 in another group) could be distinguished, and two mitogenomes (clone 10908-06 and OKA15) were not consistent with those or with each other. Significant differences in the repeat structure of the 10 mitogenomes were found, as was recombination events leading to multiple sub-genomic circles. Comparison between individual molecules revealed a translocation of ∼774 bp region located between a short repeat of 40 bp in molecule 3 of each mitogenome, and an insertion of the same in molecule 2 of the 10908-06 mitogenome. Finally, phylogenetic analyses revealed a close relationship between the mitogenomes of these clones and previously published potato mitogenomes.     

Free access of published DNA sequences facilitates regular control of (meta-) data quality – an example from shorebird mitogenomes (Aves,Charadriiformes: Charadrius)

Online repositories of DNA sequences are a rich and indispensable source of comparative data for biodiversity research and taxonomic studies. Despite increasingly high data quality of published sequences and associated metadata, particular attention should be paid to taxonomic assignment of DNA sequences, in particular if voucher specimens are not available or cannot be examined. In this study, two nearly identical mitogenomes of two distinctive plover species (Charadrius alexandrinus and Charadrius placidus) were re-analysed and compared with a comprehensive dataset of DNA-barcode sequences (cytochrome-oxidase subunit 1, COI) for 55 shorebird species. Phylogenetic analysis separated the two plover species into two reciprocally monophyletic clades that differed by mean p-distances of 11.5–14.7%; however, the COI sequence from the C. placidus mitogenome was nested in the Kentish Plover clade (C. alexandrinus). A similar mismatch was found for another DNA-barcode sequence from a Charadrius mongolus mitogenome that clustered with one of two clades of Charadrius leschenaultii in the COI tree. These results strongly suggest that, to date, two of seven mitogenomes published for Charadriidae are not representative of the taxon names to which the respective GenBank entries were assigned. Only a few DNA-barcode sequences were associated with outdated taxonomy, while others were suspected to be chimeric sequences. Thus, free access to digital sequence information is a key factor for steady improvement of data quality in online repositories via swarm intelligence of the scientific community.     

The complete mitochondrial genome sequence of the world's largest fish,the whale shark (Rhincodon typus), and its comparison with those of related shark species

The whale shark (Rhincodon typus) is the largest extant species of fish, belonging to the order Orectolobiformes. It is listed as a “vulnerable” species on the International Union for Conservation of Nature (IUCN)'s Red List of Threatened Species, which makes it an important species for conservation efforts. We report here the first complete sequence of the mitochondrial genome (mitogenome) of the whale shark obtained by next-generation sequencing methods. The assembled mitogenome is a 16,875 bp circle, comprising of 13 protein-coding genes, two rRNA genes, 22 tRNA genes and a control region. We also performed comparative analysis of the whale shark mitogenome to the available mitogenome sequences of 17 other shark species, four from the order Orectolobiformes, five from Lamniformes and eight from Carcharhiniformes. The nucleotide composition, number and arrangement of the genes in whale shark mitogenome are the same as found in the mitogenomes of the other members of the order Orectolobiformes and its closest orders Lamniformes and Carcharhiniformes, although the whale shark mitogenome had a slightly longer control region. The availability of mitogenome sequence of whale shark will aid studies of molecular systematics, biogeography, genetic differentiation, and conservation genetics in this species.     

陆川小笠贝线粒体全基因组测序及笠贝科系统发育分析

为对笠贝科进行系统发育分析,研究通过二代测序技术得到了陆川小笠贝(Lottia luchuana)的线粒体全基因组,对基因组基本结构特点做了分析,发现共含有38个基因,包含13个蛋白质编码基因(PCGs), 2个RNA,23个tRNA。对碱基含量分析发现T碱基含量最高为32.34%, C碱基最低为14.99%,选择笠贝科13个物种的线粒体基因组进行选择压力分析发现所有PCGs都受到纯化选择。另外通过结合腹足纲下6个亚纲的线粒体基因组的13个PCGs构建了系统发育树,发现笠贝科为单系群,与帽贝科Patellidae具有较近的亲缘关系。对笠形腹足亚纲的线粒体基因重排进行比较发现笠贝科在笠形腹足亚纲中表现出最广泛的不规律的重排。从重建的笠形腹足亚纲的分歧时间的年代图谱,得到笠贝的分化最早发生在中生代侏罗纪时期,在新生代物种大量分化。研究结果有助于理解不同笠贝物种的亲缘关系,以及腹足纲内各亚纲之间的进化地位与关系。     

社鼠（Niviventer confucianus）线粒体基因组全序列分析

社鼠（Niviventer confucianus）属于啮齿目（Rodentia）、鼠科（Muridae）、白腹鼠属（Niviventer）,关于该物种的分子系统学研究极少。为获取社鼠线粒体基因组全序列,提取其基因组总DNA,参照近缘物种线粒体基因组全序列设计34对特异性引物,利用PCR扩增全部片段后进行测序,之后对其基因组组成及结构特点进行了初步分析。结果表明,社鼠线粒体基因组全序列长16 281 bp（GenBank收录号：KJ152220）,包含22个tRNA基因、13个蛋白质编码基因、2个rRNA基因和1个非编码控制区;基因组核苷酸组成为34.0%A、28.6%T、24.9%C、12.5%G。将所得序列与社鼠近缘物种（川西白腹鼠、小家鼠、褐家鼠）的线粒体全基因组进行比较,结果显示,四个物种的线粒体基因组虽然在基因组大小、部分tRNA二级结构、部分蛋白质编码基因的起始或终止密码子及控制区长度和碱基组成上有差异,但基因组结构和序列特征方面都具有较高的相似性。四个物种线粒体全基因组间的遗传距离显示,社鼠与川西白腹鼠距离最近,而与小家鼠距离最远。该研究为利用线粒体全基因组信息进行啮齿类分子系统学研究提供了有价值的资料。     

The complete mitochondrial genome of <Emphasis Type="Italic">Damora sagana</Emphasis> and phylogenetic analyses of the family Nymphalidae

The monotypic genus Damora (Nymphalidae, Heliconiinae) contains a single species, Damora sagana, which is widely distributed across southern China. Herein, its complete mitogenome was sequenced to further understand lepidopteran mitogenome characteristics, reconstruct the nymphalid family phylogeny, and infer the subdivision of Heliconiinae species. The circular mitogenome was 15,151 bp long, abundant in A and T, and comprised of 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, 2 ribosomal RNA (rRNA) genes, and one control region with a gene arrangement typical of lepidopteran mitogenomes. ATN codons initiated all PCGs, except cytochrome c oxidase subunit 1 (COX1), which was initiated by a CGA sequence as has been observed in other lepidopterans. Three PCGs (COX1, COX2 and ND4) employed a single T termination signal, whereas others had the typical complete termination codon (TAA). All tRNA genes were folded into the typical cloverleaf structure except for tRNA-Ser (AGN). The A+T-rich region included the conserved motif ‘ATAGA’ followed by a 17 bp poly-T stretch, which was also observed in tribe Argynnini mitogenomes. A phylogenetic tree was constructed via multiple methods using the 13 PCGs data of D. sagana and other available mitogenomes of nymphalid species. All three phylogenetic trees yielded the same topology. These results were consistent with those from previous studies of most major nymphalid groups, except those regarding tribe subdivision in certain subfamilies such as Argynnini + (Acraeini + Heliconiini) for Heliconiine. Furthermore, our analyses identified that the genus Cethosia was grouped with the genus Acraea composing the tribe Acraeini with strong support.     

Complete mitochondrial genome from South American catfish <Emphasis Type="Italic">Pseudoplatystoma reticulatum</Emphasis> (Eigenmann &amp; Eigenmann) and its impact in Siluriformes phylogenetic tree

The cachara (Pseudoplatystoma reticulatum) is a Neotropical freshwater catfish from family Pimelodidae (Siluriformes) native to Brazil. The species is of relative economic importance for local aquaculture production and basic biological information is under development to help boost efforts to domesticate and raise the species in commercial systems. The complete cachara mitochondrial genome was obtained by assembling Illumina RNA-seq data from pooled samples. The full mitogenome was found to be 16,576 bp in length, showing the same basic structure, order, and genetic organization observed in other Pimelodidae, with 13 protein-coding genes, 2 rNA genes, 22 trNAs, and a control region. Observed base composition was 24.63% T, 28.47% C, 31.45% A, and 15.44% G. With the exception of NAD6 and eight tRNAs, all of the observed mitochondrial genes were found to be coded on the H strand. A total of 107 SNPs were identified in P. reticulatum mtDNA, 67 of which were located in coding regions. Of these SNPs, 10 result in amino acid changes. Analysis of the obtained sequence with 94 publicly available full Siluriformes mitogenomes resulted in a phylogenetic tree that generally agreed with available phylogenetic proposals for the order. The first report of the complete Pseudoplatystoma reticulatum mitochondrial genome sequence revealed general gene organization, structure, content, and order similar to most vertebrates. Specific sequence and content features were observed and may have functional attributes which are now available for further investigation.