Interspecific Genetic Distances Research Articles

Comparison of the Complete Eragrostis pilosa Chloroplast Genome with Its Relatives in Eragrostideae (Chloridoideae; Poaceae).

Eragrostis of the tribe Eragrostideae is a taxonomically complex genus, because of its polyploid nature and the presence of similar morphological characters among its species. However, the relationship between these morphologically indistinguishable species at the genomic level has not yet been investigated. Here, we report the complete chloroplast genome of E. pilosa and compare its genome structures, gene contents, simple sequence repeats (SSRs), sequence divergence, codon usage bias, and Kimura 2-parameter (K2P) interspecific genetic distances with those of other Eragrostideae species. The E. pilosa chloroplast genome was 134,815 bp in length and contained 132 genes and four regions, including a large single-copy region (80,100 bp), a small single-copy region (12,661 bp), and a pair of inverted repeats (21,027 bp). The average nucleotide diversity between E. pilosa and E. tef was estimated to be 0.011, and 0.01689 among all species. The minimum and maximum K2P interspecific genetic distance values were identified in psaA (0.007) and matK (0.029), respectively. Of 45 SSRs, eight were shared with E. tef, all of which were in the LSC region. Phylogenetic analysis resolved the monophyly of the sampled Eragrostis species and confirmed the close relationship between E. pilosa and E. tef. This study provides useful chlorophyll genomic information for further species identification and phylogenetic reconstruction of Eragrostis species.

Morphological characteristics identification and molecular DNA barcoding analysis of Hippocampus spinosissimus

The combination of morphological characteristics and DNA barcodes was used to a systematic study of Hippocampus spinosissimus,laying the foundation for rapid and accurate identification for the medical seahorse species. According to the reported literature and observation on seahorse samples,the typical characteristics of the H. spinosissimus include highly developed spiny,much short nose,single or double cheeks and strongly developed spines bordering pouch. Genomic DNAs of H. spinosissimus and other related seahorse species were extracted using the TIANamp Marine Animals DNA Kit. The COⅠ and ATP6 genes were amplified and sequenced in both directions. After the verification by Blast,the GC content,intraspecific and interspecific genetic distance,and the Neighbor joining( NJ) phylogenetic trees were analyzed by MEGA 7. The lengths of the COⅠ and ATP6 genes were 649 bp and 602-603 bp,respectively,with the average GC content of 39. 96% and 35. 37%. The maximum intraspecific genetic distances in H. spinosissimus based on COⅠ and ATP were both far less than the minimum interspecific genetic distance between H. spinosissimus and other seahorses,suggesting a significant barcoding gap. NJ analysis results of COⅠ and ATP6 exhibited that all H. spinosissimus species clustered together,indicating that the two DNA barcode could identify H. spinosissimus from other seahorses accurately and quickly. In addition,H. spinosissimus shared a close genetic relationship between H. kelloggi according to the NJ tree. Furthermore,there exits three stable subgroup structure of H. spinosissimus,indicating that COⅠ and ATP6 barcodes could be applied the indicator for the geographical ecology research of H. spinosissimus. The results obtained the typical morphological and molecular identification characteristics of H. spinosissimus,which played central roles for the development of species identification. This study provides an important basis data for expanding the medical seahorse resources and ensuring the safety of clinical medicine.

Integrating DNA Barcoding and Traditional Taxonomy for the Identification of Dipterocarps in Remnant Lowland Forests of Sumatra.

DNA barcoding has been used as a universal tool for phylogenetic inferences and diversity assessments, especially in poorly studied species and regions. The aim of this study was to contrast morphological taxonomy and DNA barcoding, using the three frequently used markers matK, rbcL, and trnL-F, to assess the efficiency of DNA barcoding in the identification of dipterocarps in Sumatra, Indonesia. The chloroplast gene matK was the most polymorphic among these three markers with an average interspecific genetic distance of 0.020. The results of the molecular data were mostly in agreement with the morphological identification for the clades of Anthoshorea, Hopea, Richetia, Parashorea, and Anisoptera, nonetheless these markers were inefficient to resolve the relationships within the Rubroshorea group. The maximum likelihood and Bayesian inference phylogenies identified Shorea as a paraphyletic genus, Anthoshorea appeared as sister to Hopea, and Richetia was sister to Parashorea. A better discriminatory power among dipterocarp species provided by matK and observed in our study suggests that this marker has a higher evolutionary rate than the other two markers tested. However, a combination of several different barcoding markers is essential for reliable identification of the species at a lower taxonomic level.

Phylogeny of certain members of Hyrcanus group (Diptera: Culicidae) in China based on mitochondrial genome fragments

BackgroundSpecies of the Anopheles hyrcanus group are widely distributed in Palearctic and Oriental regions and some of them are important malaria vectors. The cryptic species of An. hyrcanus group was almost impossible to identify based only on their morphology. The phylogenetic relationship of An. hyrcanus group was also not clear.MethodsFive members of An. hyrcanus group were identified by rDNA ITS2 sequencing as An. yatsushiroensis, An. belenrae, An. kleini, An. lesteri and An. sineroides. The mitochondrial genome fragments were sequenced and annotated using the mitochondrial genome of An. sinensis as reference. Based on the four segments and Joint Data sequences of these species, and other four anopheline species downloaded from GenBank, intraspecific as well as interspecific genetic distances were calculated and the phylogenetic trees were reconstructed by the methods of neighbor joining, maximum parsimony, minimum evolution and maximum likelihood.FindingsFour parts of mitochondrial genomes, which were partial fragments COI + tRNA + COII (F5), ATP6 + COIII(F7 + F8), ND1(F19) and lrRNA (F21), were obtained. All fragments were connected as one sequence (referred as Joint Data), which had a total length of 3393 bp. All fragment sequences were highly conservative within species, with the maximum p distance (0.026) calculated by F19 of An. belenrae. The pairwise interspecific p distance calculated by each fragment showed minor or even no difference among An. sinensis, An. kleini and An. belenrae. However, interspecific p distances calculated by the Joint Data sequence ranged from 0.004 (An. belenrae vs An. kleini) to 0.089 (An. sineroides vs An. minimus), and the p distances of the six members of An. hyrcanus group were all less than 0.029. The phylogenetic tree showed two major clades: all subgenus Anopheles species (including six members of An. hyrcanus group, An. atroparvus and An. quadrimaculatus A) and subgenus Cellia (including An. dirus and An. minimus). The An. hyrcanus group was divided into two clusters as ((An. lesteri, An. sineroides) An. yatsushiroensis) and ((An. belenrae, An. sinensis) An. kleini)).ConclusionsThe An. hyrcanus group in this study could be divided into two clusters, in one of which An. belenrae, An. sinensis and An. kleini were most closely related. More molecular markers would make greater contribution to phylogenetic analysis.

Hidden biodiversity revealed by integrated morphology and genetic species delimitation of spring dwelling water mite species (Acari, Parasitengona: Hydrachnidia)

BackgroundWater mites are among the most diverse organisms inhabiting freshwater habitats and are considered as substantial part of the species communities in springs. As parasites, Hydrachnidia influence other invertebrates and play an important role in aquatic ecosystems. In Europe, 137 species are known to appear solely in or near springheads. New species are described frequently, especially with the help of molecular species identification and delimitation methods. The aim of this study was to verify the mainly morphology-based taxonomic knowledge of spring-inhabiting water mites of central Europe and to build a genetic species identification library.MethodsWe sampled 65 crenobiontic species across the central Alps and tested the suitability of mitochondrial (cox1) and nuclear (28S) markers for species delimitation and identification purposes. To investigate both markers, distance- and phylogeny-based approaches were applied. The presence of a barcoding gap was tested by using the automated barcoding gap discovery tool and intra- and interspecific genetic distances were investigated. Furthermore, we analyzed phylogenetic relationships between different taxonomic levels.ResultsA high degree of hidden diversity was observed. Seven taxa, morphologically identified as Bandakia concreta Thor, 1913, Hygrobates norvegicus (Thor, 1897), Ljania bipapillata Thor, 1898, Partnunia steinmanni Walter, 1906, Wandesia racovitzai Gledhill, 1970, Wandesia thori Schechtel, 1912 and Zschokkea oblonga Koenike, 1892, showed high intraspecific cox1 distances and each consisted of more than one phylogenetic clade. A clear intraspecific threshold between 5.6–6.0% K2P distance is suitable for species identification purposes. The monophyly of Hydrachnidia and the main superfamilies is evident with different species clearly separated into distinct clades. cox1 separates water mite species but is unsuitable for resolving higher taxonomic levels.ConclusionsWater mite species richness in springs is higher than has been suggested based on morphological species identification alone and further research is needed to evaluate the true diversity. The standard molecular species identification marker cox1 can be used to identify species but should be complemented by a nuclear marker, e.g. 28S, to resolve taxonomic relationships. Our results contribute to the taxonomical knowledge on spring inhabiting Hydrachnida, which is indispensable for the development and implementation of modern environment assessment methods, e.g. metabarcoding, in spring ecology.

New records and their associated DNA barcodes of the butterfly familyHesperiidae in Tibet, China.

The specimens of the family Hesperiidae collected from Tibet during 2016-2018 are identified using morphology. COI sequences of 76 individuals are newly obtained. The result of our morphological study is congruent with COI gene analyses. Maximum likehood (ML) and Bayesina inferences (BI) analyses reveal that individuals identified morphologically as the same species cluster cohesively. The minimum interspecific genetic distance is 1.7% between Halpe aucma and H. filda, and the genetic distance between conspecific individuals ranged from 0 to 0.2% for the genus Halpe. A total of 51 species are recognized, and six of them, Celaenorrhinus consanguineus Leech, 1891, Barca bicolor (Oberthür, 1896), Aeromachus propinquus Alphéraky, 1897, Pedesta bivitta (Oberthür, 1886), Baoris penicillata chapmani Evans, 1937, and Ochlodes brahma Moore, 1878, are reported from Tibet for the first time, and the last species is new to China.

<p class="Body"><strong>Feather mites of the family Ptyssalgidae (Acari: Analgoidea) associated with hummingbirds and suboscine passerines—A morphological review supplemented by CO1 barcode sequences</strong></p>

To date, the feather mite family Ptyssalgidae (Acariformes: Analgoidea) has been known from a single species associated with hummingbirds (Apodiformes: Trochilidae). Here, based on our collecting in Mexico, we describe (i) a new genus and species, Tyrannoptyssalges striatus gen. n., sp. n., from a passerine host Tolmomyias sulphurescens (Passeriformes: Tyrannidae) and (ii) four new species of the genus Ptyssalges Atyeo and Gaud, 1979 from hummingbirds (Apodiformes: Trochilidae): Ptyssalges amaziliae sp. n. from Amazilia rutila (Delattre) (type host), A. candida (Bourcier & Mulsant) and A. yucatanensis (Cabot), P. anthracothoracis sp. n. from Anthracothorax prevostii (Lesson, R.), P. atyeoi sp. n. from Phaethornis longirostris (Delattre), and P. campylopteri sp. n. from Campylopterus curvipennis excellens (Wetmore). In addition, we redescribe Ptyssalges major (Trouessart, 1887), the type species of the genus, based on newly collected material from the type host, Eutoxeres aquila, from Panama. Standard morphological descriptions of all mite species are supplemented by CO1 barcoding sequence data. In the genus Ptyssalges, CO1 K2P interspecific genetic distances were 11.39–11.89%, while distances between the single species of Tyrannoptyssalges and species of the genus Ptyssalges were 16.34–17.87%. New, amended diagnoses for the family Ptyssalgidae and the genus Ptyssalges and a key to all known ptyssalgid species are provided. Preliminary hypotheses on the origin and ancestral host associations of ptyssalgids are briefly discussed.

First molecular phylogeny of Paralucilia Brauer & Bergenstamm, 1891 (Insecta, Diptera, Calliphoridae): A preliminary approach

Paralucilia Brauer & Bergenstamm, 1891 (Diptera, Oestroidea, Calliphoridae) is a small genus of blowflies restricted to the Neotropical region, which is commonly reported on decaying corpses and vertebrate carcasses. The number of species currently assigned to this genus and their denominations are contentious, with either three or five species recognized by different authors. This taxonomic instability results in a lack of consensus in species determination, making it impossible to compare results from different studies as well as to elaborate confident taxonomic keys. In order to solve some of the most commonly reported taxonomic conflicts within this genus, to the best of our knowledge, this study presents the first phylogenetic hypothesis for the relationships among Paralucilia species, based on molecular analysis of the COI, ITS2, 28S, and 16S genes. Maximum parsimony, maximum likelihood, and Bayesian inference analyses were used for phylogenetic reconstruction and divergence time estimation analyses. Intra- and interspecific genetic distances were calculated among species using the COI dataset. The results showed that at least three of the five currently accepted species are well defined: P. fulvinota, P. pseudolyrcea, and P. paraensis, however, a significant level of intraspecific variation was observed in P. fulvinota. These findings will assist future revisions of the description, classification, and distribution of species of Paralucilia, as well as in the elaboration of taxonomic keys. Additionally, we show that it is possible to clarify the evolutionary history of this Neotropical genus using supplementary evidence such as morphology and molecular data.

DNA barcoding cannot discriminate between Sardinella tawilis and S. hualiensis (Clupeiformes: Clupeidae)

Sardinella tawilis, the only known freshwater sardinella in the world, is endemic to Taal Lake, Philippines. Previous studies found the Taiwan sardinella, S. hualiensis, to be morphologically very similar to S. tawilis and identified it as the marine sister species of S. tawilis. In this study, DNA barcoding using the mitochondrial cytochrome c oxidase I (COI) gene was carried out to analyze species demarcation in the Sardinella genus, focusing primarily on the relationship between S. tawilis and S. hualiensis. The neighbour-joining (NJ) tree that was constructed using Kimura 2-parameter (K2P) model showed a single clade for the two species with 100% bootstrap support. K2P interspecific genetic divergence ranged from 0% to 0.522%, which is clearly below the suggested 3–3.5% cutoff for species discrimination. Recombination activating gene 1 (RAG1), mitochondrial control region (CR), cytochrome b, 16S rRNA, and S7 markers were used to further validate the results. Sardinella tawilis and S. hualiensis clustered together with a bootstrap support of 99–100% in each of the NJ trees. Low interspecific genetic distances between S. tawilis and S. hualiensis for all the markers except CR could be attributed to incipient allopatric speciation.

The Complete Mitochondrial Genome of Platysternon megacephalum peguense and Molecular Phylogenetic Analysis.

Platysternon megacephalum is the only living representative species of Platysternidae and only three subspecies remain: P. m. megalorcephalum, P. m. shiui, and P. m. peguense. However, previous reports implied that P. m. peguense has distinct morphological and molecular features. The characterization of the mitogenome has been accepted as an efficient means of phylogenetic and evolutionary analysis. Hence, this study first determined the complete mitogenome of P. m. peguense with the aim to identify the structure and variability of the P. m. peguense mitogenome through comparative analysis. Furthermore, the phylogenetic relationship of the three subspecies was tested. Based on different tRNA gene loss and degeneration of these three subspecies, their rearrangement pathways have been inferred. Phylogenetic analysis showed that P. m. peguense is a sister group to (P. m. megalorcephalum and P. m. shiui). Furthermore, the divergence time estimation of these three subspecies coincided with the uplift of the Tibetan Plateau. This study shows that the genetic distances between P. m. peguense and the other two subspecies are comparable to interspecific genetic distances, for example within Mauremys. In general, this study provides new and meaningful insights into the evolution of the three Platysternidae subspecies.

Revised phylogeography of the common whelk Buccinum undatum (Gastropoda: Buccinidae) across the North Atlantic

AbstractThe purpose of this study was to revisit the mitochondrial genetic divergence of North Atlantic populations of the subtidal gastropod Buccinum undatum, because previous mitochondrial DNA (mtDNA) analysis by Pálsson et al. (2014) included 16S ribosomal RNA sequences that were incorrectly assigned to the species. In the present study, population mtDNA variation is now assessed using COI sequences obtained from previous research (Pálsson et al., 2014) and, to increase the geographical cover of the study, data from recently assembled transcriptomes of 96 Icelandic whelks (Jónsson et al., 2019) and GenBank are also used. To estimate the mtDNA divergence in B. undatum across the North Atlantic, two species screening indices were used: automatic barcode gap discovey (ABGD; Puillandre et al., 2012a) and species screening threshold index (SSTI; Witt et al., 2006). Phylogenetic reconstruction revealed monophyletic Eastern and Western North Atlantic whelk lineages, which diverged early in the Pleistocene glaciation (2.1 Mya), followed by a subsequent divergence event between Greenlandic and Canadian populations at 1.3 Mya. Species screening indices, ABGD and SSTI, indicated cryptic speciation or allopatric divergence. Genetic distances between populations from the two continents were similar to or greater than interspecific genetic distances across several North Pacific and North Atlantic Buccinum species.

Plant DNA-barcode library and community phylogeny for a semi-arid East African savanna.

Applications of DNA barcoding include identifying species, inferring ecological and evolutionary relationships between species, and DNA metabarcoding. These applications require reference libraries that are not yet available for many taxa and geographic regions. We collected, identified, and vouchered plant specimens from Mpala Research Center in Laikipia, Kenya, to develop an extensive DNA-barcode library for a savanna ecosystem in equatorial East Africa. We amassed up to five DNA barcode markers (rbcL, matK, trnL-F, trnH-psbA, and ITS) for 1,781 specimens representing up to 460 species (~92% of the known flora), increasing the number of plant DNA barcode records for Africa by ~9%. We evaluated the ability of these markers, singly and in combination, to delimit species by calculating intra- and interspecific genetic distances. We further estimated a plant community phylogeny and demonstrated its utility by testing if evolutionary relatedness could predict the tendency of members of the Mpala plant community to have or lack "barcode gaps", defined as disparities between the maximum intra- and minimum interspecific genetic distances. We found barcode gaps for 72%-89% of taxa depending on the marker or markers used. With the exception of the markers rbcL and ITS, we found that evolutionary relatedness was an important predictor of barcode-gap presence or absence for all of the markers in combination and for matK, trnL-F, and trnH-psbA individually. This plant DNA barcode library and community phylogeny will be a valuable resource for future investigations.

A new species of black fly (Diptera: Simuliidae) in the Simulium (Simulium) multistriatum species-group from Thailand.

A new black fly species of the Simulium multistriatum species-group of the subgenus Simulium Latreille is described from the mountainous area in northeastern Thailand, based on morphology and mitochondrial DNA sequences. The new species is morphologically similar to S. laui Takaoka and Sofian-Azirun and S. lacduongense Takaoka and Ya'cob originally described from Vietnam, S. fenestratum Edwards originally described from Indonesia and S. chaliowae Takaoka and Boonkemtong originally described from Thailand, but can be distinguished in the adult stage by the number of upper eye facets and globular shape of the spermatheca and in the pupal stage by the cocoon and shape of thoracic tubercles. Genetic distance and phylogenetic analyses of mitochondrial cytochrome c oxidase I sequences differentiated the new species from other members of S. multistriatum species-group. All specimens of the new species formed a monophyletic clade with strong support in all phylogenetic analyses. The minimum interspecific genetic distance of 4.9% is considerably greater than the new species maximum intraspecific genetic distance (2.7%).

Phylogeography of Simulium Subgenus Wilhelmia (Diptera: Simuliidae)-Insights From Balkan Populations.

Many morphologically similar species of the simuliid (Diptera: Simuliidae) subgenus Wilhelmia, Enderlein are difficult to distinguish. Thus, the revision of the subgenus using various morphological, cytogenetic, and genetic analyses has been attempted. Neglected until now, the Balkan Peninsula, a crossroad between Europe and Anatolia, provides insight which could resolve problematic interrelationships of the taxa within this subgenus. To uncover the status and relations within the subgenus Wilhelmia, mtDNA was extracted from 47 individuals of six morphospecies: Simulium balcanicum (Enderlein, 1924), Simulium turgaicum Rubtsov, 1940, Simulium lineatum (Meigen, 1804), Simulium pseudequinum Séguy, 1921, Simulium equinum (Linnaeus, 1758), and Simulium paraequinum Puri, 1933 from 21 sites throughout the Balkan Peninsula. Phylogenetic analysis of the Wilhelmia species using mitochondrial DNA barcoding (COI) gene showed two major branches, the lineatum branch, which includes the lineages sergenti, paraequinum, and lineatum, and the equinum branch. In the equinum branch, the mtDNA sequences formed six clades, with high genetic distances, suggesting the existence of different species. Historically, the clades of the equinum branch appeared at numerous islands, perhaps as a result of allopatric speciation. The paraequinum lineage (lineatum branch) is composed of two species. However, six clades of the lineatum lineage overlapped with intra- and interspecific genetic distances. Our results revealed that the species S. balcanicum, S. pseudequinum B, and S. equinum were omnipresent in the Balkans. The results point to not only the fair diversity of Wilhelmia species in the Balkans, but also indicate that most Wilhelmia species live in sympatry.

DNA barcodes and evidence of cryptic diversity of anthropophagous mosquitoes in Quintana Roo, Mexico.

Culicidae mosquitoes are potential vectors of pathogens that affect human health. The correct species identification, as well as the discovery and description of cryptic species, is important in public health for the control and management of specific vectors. In the present study, the diversity of anthropophagous mosquitoes in Quintana Roo, at the border between Mexico and Belize, was evaluated using morphological and molecular data (COI‐DNA Barcoding). A total of 1,413 adult female specimens were collected, belonging to eight genera and 31 morphospecies. Most species formed well‐supported clades. Intraspecific Kimura 2 parameters (K2P) distance average was 0.75%, and a maximum distance of 4.40% was observed for Anopheles crucianss.l. ABGD method identified 28 entities, while 32 entities were identified with the BIN system. In Culex interrogator and Culex nigripalpus a low interspecific genetic distance of 0.1% was observed. One undescribed species belonging to the genus Aedes (Aedesn. sp.) was discovered, but no clear genetic divergence was found between this species and the closely related species Aedes angustivittatus. An intraspecific K2P distance greater than 2.7% was observed in Aedes serratus(3.9%), Anopheles crucianss.l. (4.4%), Culex taeniopus (3.7%), Haemagogus equinus (3.9%), Culex erraticus (5.0%), Psorophora ferox (4.5%), and in Anopheles apicimacula(8.10%); therefore, evidences of cryptic diversity are shown in these species. This study showed that DNA barcodes offer a reliable framework for mosquito species identification in Quintana Roo, except for some closely related species for which it is recommended to use additional nuclear genetic markers such as ITS2, in order to resolve these small discrepancies.

Influence of pairwise genetic distance computation and reference sample size on the reliability of species identification using Cyt b and COI gene fragments in a group of native passerines

Species identification is fundamental to wildlife forensic practice. The desirability of molecular genetic methods is increasing rapidly. The sequence of a marker, rather than its particular diagnostic nucleotides, provides greater safety through comparisons between intra- and inter-specific pairwise genetic distances. However, it has not been well described how reliability of species assignment is influenced by distance computing methods and reference sample sizes. In this study, the influences were tested using 12 species from 4 genera of passerine birds and the sequences of partial Cytochrome b (Cyt b) and Cytochrome Oxidase subunit I (COI) genes. Results showed that different substitution types have different outcomes of pairwise genetic distance estimation and this influences the risk of false inclusion and exclusion. Transition (Ts) is the most effective substitution type to reveal optimal species resolution for both Cyt b and COI gene fragments no matter whether K2P and p-distance are used. Sample size required to accurately estimate pairwise distance is essentially determined by the genetic diversity of a species in reference to a given strictness of predefined acceptable accuracy. These findings suggest that for future forensic work on birds by use of Cyt b and COI gene fragments, transition should be used exclusively for marker validation and identification practice when targeting closely related species. Meanwhile, the reference database should sufficiently represent overall genetic diversity of the species. The minimum sample size should be estimated based on existing knowledge of genetic diversity. Special caution should be used for species assignment when only several reference data are available for animals that are considered likely to have high genetic diversity.

DNA barcoding identified selected ornamental fishes in Murti river of East India

Nomenclature for the nameless is one of the successful events after the invention of the DNA barcoding technique in biodiversity research. The ornamental fish species are frequently hunted from the east and northeast India and trafficked with various elusive names and high demanding values. Such illegitimate trading stimulated the severe threats on the native freshwater ecosystems and their indigenous biodiversity. Both traditional taxonomy and DNA barcoding technique successfully identified 11 ornamental fish species from a small riverine system, Murti river; linked up with three protected areas in the northern part of West Bengal. To test the efficacy of DNA barcode data for species identification, the generated sequences were subjected to similarity search results, and Neighbour-Joining tree clustering and genetic divergences. The mean genetic divergence was 21.3% and the interspecific genetic distance was ranging from 17.8% to 28.7% in the studied dataset. The detected high intraspecific genetic divergence in Opsarius barna (14.1%) and Channa gachua (6.4%) in the present dataset suggested further genetic investigation from their known distributions.

Complete mitochondrial genome of Stichaeus nozawae Jordan & Snyder 1902 (Zoarcales: Stichaeidae)

We report on the structure and composition of the first complete mitochondrial genome of Stichaeus nozawae (typical prickleback fish (Zoarcales, Stichaeidae)), obtained by dideoxy (Sanger) sequencing technique. Genome has a classic organization with 13 genes, 2 rRNAs, control region, and 22 tRNAs, including additional tRNAs with atypical codons previously found in many eelpouts. Phylogenetic analysis confirms the species identity of S. nozawae and validate its recent divergence from S. grigorjewi with unusually low interspecific genetic distance.

Comprehensive DNA barcodes for species identification and discovery of cryptic diversity in mayfly larvae from South Korea: Implications for freshwater ecosystem biomonitoring

AbstractDNA barcoding of aquatic macroinvertebrates holds much promise as a tool for taxonomic research and for providing baseline reference for phylogenetic analysis and aquatic ecosystem biomonitoring. We obtained 112 novel sequences of the barcode region of the mitochondrial DNA cytochrome c oxidase subunit I gene representing 11 families, 25 genera, and 43 species of mayfly (Insecta: Ephemeroptera) from South Korea. No species shared barcode sequences and all can be identified with barcodes with a possible exception of some species. Minimum levels of interspecific genetic distances ranged from 6.7 to 32.9% (mean: 23.7%), whereas average levels of intraspecific divergence was 3.7%. The latter value was inflated by the presence of very high divergences within some taxa. In fact, approximately 33.3% (15/45) of the species included two or more haplotype clusters showing greater than 5.0% sequence divergence and some values were as high as 32.9%. Many of the species with high intraspecific divergences are para‐ or polyphyletic and represent the possibility of species complexes. Our study suggests that type or topotype specimens should be sequenced to identify accurate barcoding clusters with morphological species concepts and also to determine the status of currently synonymized species.

New Data on the Systematics of Comb-fin Squids Chtenopteryx spp. (Cephalopoda: Chtenopterygidae) from the Canary Islands.

Alejandro Escánez, Álvaro Roura, Rodrigo Riera, Ángel Francisco González, and Ángel Guerra (2018) The systematics of the comb-fin squid species is problematic and poorly resolved. In total, 53 specimens of comb-fin squids (Chtenopteryx spp.) were caught at depths ranging from 30 to 800 m off the Canary Islands (NE Atlantic Ocean). Mantle lengths of the individuals ranged from 18 to 43 mm and the sample included immature, mature male and mature female specimens. Two species of comb-fin squids, Chtenopteryx canariensis and C. sicula, were identified by combining traditional morphological characters with a molecular analysis of a fragment of the cytochrome c oxidase subunit I (COI) gene. Intra- and interspecific genetic distances and maximum likelihood tree analyses based on COI sequences available from GenBank suggest the existence of at least four species, two from the Pacific and two from the Atlantic Ocean. Our data expand the current geographic range of C. canariensis from the NE to NW Atlantic. In the GenBank database, several sequences of comb-fin squid in different species-specific clades have been attributed only to C. sicula, indicating the possible existence of cryptic species and the need to re-analyse these data.