Barcode Index Numbers Research Articles

DNA barcodes for Aotearoa New Zealand Pyraloidea (Lepidoptera).

Identification of pyraloid species is often hampered by highly similar external morphology requiring microscopic dissection of genitalia. This becomes especially obvious when mass samples from ecological studies or insect monitoring have to be analysed. DNA barcode sequences could accelerate identification, but are not available for most pyraloid species from New Zealand. Hence, we are presenting a first DNA-barcode library for this group, providing 440 COI barcodes (cytochrome C oxidase I sequences) for 73 morphologically-identified species, which is 29% of Pyraloidea known from New Zealand. Results are analysed using the Barcode Index Number system (BIN) of BOLD and the Automatic Barcode Gap Discovery method (ABGD).Using BIN, the 440 barcodes reveal 82 clusters. A perfect match between BIN assignment and morphological identification was found for 63 species (86.3%). Four species (5.5%) share BINs, each with two species in one BIN, of which Glaucocharis epiphaea and Glaucocharis harmonica even share the same barcode. In contrast, six species (8.2%) split into two or more BINs, with the highest number of five BINs for Orocrambus ramosellus. The interspecific variation of all collected specimens of New Zealand Pyraloidea averages 12.54%. There are deep intraspecific divergences (> 2%) in seven species, for instance Orocrambus vulgaris with up to 6.6% and Scoparia ustimacula with 5.5%.Using ABGD, the 440 barcodes reveal 71 or 88 operational taxonomic units (OTUs), depending on the preferred partition. A perfect match between OTU and morphological identification was found for 56 species (76.7%) or 62 species (84.9%). ABGD delivers four or seven species sharing OTUs and four or ten species split into more than one OTU.Morphological re-examination, as well as the analysis of a concatenated dataset of COI and the nuclear markers EF1α and GADPH for species split into more than one BIN or OTU, do not support a higher number of species. Likewise, there is no evidence for Wolbachia infection as a trigger for these sequence variations.

Successful post-glacial colonization of Europe by single lineage of freshwater amphipod from its Pannonian Plio-Pleistocene diversification hotspot

Gammarus roeselii Gervais, 1835 is a morphospecies with a wide distribution range in Europe. The Balkan Peninsula is known as an area of pre-Pleistocene cryptic diversification within this taxon, resulting in at least 13 Molecular Operational Taxonomic Units (MOTUs). The morphospecies diversified there during Neogene and has probably invaded other parts of the continent very recently, in postglacial or even historical times. Thus, the detailed goals of our study were to (1) identify which lineage(s) colonized Central-Western Europe (CWE), (2) determine their possible geographical origin, (3) verify, whether the colonisation was associated with demographic changes. In total, 663 individuals were sequenced for the cytochrome oxidase I (COI) barcoding fragment and 137 individuals for the internal transcribed spacer II (ITS2). We identified two MOTUs in the study area with contrasting Barcode Index Number and haplotype diversities. The Pannonian Basin (PB) appeared to be a potential ice age refugium for the species, while CWE was colonised by a single lineage (also present in PB), displaying low genetic diversity. Our results suggest that G. roeselii is a relatively recent coloniser in CWE, starting demographic expansion around 10 kya.

BAGS: An automated Barcode, Audit & Grade System for DNA barcode reference libraries.

Biodiversity studies greatly benefit from molecular tools, such as DNA metabarcoding, which provides an effective identification tool in biomonitoring and conservation programmes. The accuracy of species-level assignment, and consequent taxonomic coverage, relies on comprehensive DNA barcode reference libraries. The role of these libraries is to support species identification, but accidental errors in the generation of the barcodes may compromise their accuracy. Here, we present an R-based application, Barcode, Audit & Grade System (BAGS) (https://github.com/tadeu95/BAGS), that performs automated auditing and annotation of cytochrome c oxidase subunit I (COI) sequences libraries, for a given taxonomic group of animals, available in the Barcode of Life Data System (BOLD). This is followed by implementing a qualitative ranking system that assigns one of five grades (A to E) to each species in the reference library, according to the attributes of the data and congruency of species names with sequences clustered in barcode index numbers (BINs). Our goal is to allow researchers to obtain the most useful and reliable data, highlighting and segregating records according to their congruency. Different tests were performed to perceive its usefulness and limitations. BAGS fulfils a significant gap in the current landscape of DNA barcoding research tools by quickly screening reference libraries to gauge the congruence status of data and facilitate the triage of ambiguous data for posterior review. Thereby, BAGS has the potential to become a valuable addition in forthcoming DNA metabarcoding studies, in the long term contributing to globally improve the quality and reliability of the public reference libraries.

Spider diversity across an elevation gradient in Área de Conservación Guanacaste (ACG), Costa Rica

AbstractThroughout the Neotropics, temperature and precipitation change with elevation and these changes affect the assemblage of species at any particular elevation. We documented the diversity of litter‐inhabiting spiders, (Arachnida: Araneae) along a Costa Rican elevational gradient as it relates to covarying abiotic factors such as temperature and precipitation. The spiders we collected were principally unidentifiable juveniles, and so we used Barcode Index Numbers (BINs) derived from DNA barcodes as proxies for species‐level interim names. We contrasted these taxon‐based estimates with phylogenetic measures of alpha‐ and beta‐diversity derived from both the mitochondrial DNA barcode region and a multi‐gene phylogeny of spiders and found that neither the abundance nor the species richness of spiders was significantly correlated with elevation, temperature, or precipitation. However, we did find that spider assemblages in the upper elevation cloud forests were phylogenetically clustered, (and this pattern was unrelated to whether the phylogenetic patterns were derived mitochondrially or from a multi‐gene analysis). One standard explanation for such a pattern is that harsh abiotic conditions in higher elevation forests have selected for particular spider lineages; however, this remains to be tested fully. The diversity of leaf‐litter spider species we uncovered was high and further sampling of spider abundance and diversity across the ACG is likely to yield many new species.

A DNA barcode library for ground beetles of Germany: the genus Agonum Bonelli, 1810 (Insecta, Coleoptera, Carabidae)

The ground beetle genusAgonumBonelli, 1810 is a large genus of the tribe Platynini with many species that show high amounts of intraspecific variations, making a correct identification challenging. As part of the German Barcode of Life initiative, this publication provides a comprehensive DNA barcode library for species ofAgonumthat are reported for Germany. In total, DNA barcodes from 258 beetles and 23 species were analysed using the Barcode of Life Data System (BOLD) workbench, including sequences from former studies and 68 newly-generated sequences. The neighbour-joining analyses, based on K2P distances, revealed distinct clustering for all studied species, with unique Barcode Index Numbers (BINs) for 15 species (65%). BIN sharing but distinct clustering was found for three species pairs:Agonum micans/Agonum scitulum,Agonum impressum/Agonum sexpunctatumandAgonum duftschmidi/Agonum emarginatum. The given dataset and its analysis represent another important step in generating a comprehensive DNA barcode library for the ground beetles of Germany and Central Europe in terms of modern biodiversity research.

Species delimitation and life stage association of Propsilocerus Kieffer, 1923 (Diptera, Chironomidae) using DNA barcodes.

The utility of COI DNA barcodes in species delimitation is explored as well as life stage associations of five closely related Propsilocerus species: Propsilocerus akamusi (Tokunaga, 1938), Propsilocerus paradoxus (Lundström, 1915), Propsilocerus saetheri Wang, Liu et Paasivirta, 2007, Propsilocerus sinicus Sæther et Wang, 1996, and Propsilocerus taihuensis (Wen, Zhou et Rong, 1994). Results revealed distinctly larger interspecific than intraspecific divergences and indicated a clear “barcode gap”. In total, 42 COI barcode sequences including 16 newly generated DNA barcodes were applied to seven Barcode Index Numbers (BINs). A neighbor-joining (NJ) tree comprises five well-separated clusters representing five morphospecies. Comments on how to distinguish the larvae of P. akamusi and P. taihuensis are provided.

A new species of Scapholeberis Schoedler, 1858 (Anomopoda: Daphniidae: Scapholeberinae) from the Colombian Amazon basin highlighted by DNA barcodes and morphology.

BackgroundThe Amazon basin is recognized as one of the most complex and species-rich freshwater environments globally. The diversity of zooplankton here remains unknown, with many species undescribed.MethodsHere, we describe a new species of Scapholeberis Schoedler, 1858 (Cladocera: Anomopoda: Daphniidae: Scapholeberinae) from the Colombian Amazon Basin, collected with recently designed light traps. The description is based on detailed morphology (based on SEM and light microscopy) of parthenogenetic females, ephippial females, males, and molecular data based on the COI gene.ResultsScapholeberis yahuarcaquensis n. sp. has a combination of characters present in Scapholeberis kingi Sars, 1888 and Scapholeberis armata freyi Dumont & Pensaert, 1983. These are a trilobate rostrum, with the middle lobe well developed with sides straight to relatively rounded, the presence of an elongated slit frontal head pore, a dorsal pore in the juncture of the cephalic shield and the valves, and a single denticulate membrane at the posterior rim of the valves, with stronger setae in the last third. The unique characters of the parthenogenetic females are ventral sucker with delicate triangles. Each has a filament-like projection in the lamellae’s inner side and an external section forming convex folds with denticle-like projections in the middle zone of the sucker-plate. There is a peculiar pitted sculpture in the ephippial females and a strong projection in the front of it. The male hook on the limb I with a blunt tip, a quirky lamella-like outgrow in the proximal side, and a paddle with well-developed spines scattered on its surface. The ventral sucker-lamellae in the male is much more developed than the female. The COI gene sequences showed an interspecific mean genetic divergence of 16.4% between S. yahuarcaquensis n. sp. and the closest species S. freyi from Mexico, supporting our results. A coalescence analysis and Barcode Index Number also support the new species based on the DNA sequences. New methods of collecting and integrative biology will give important support to recognize the fauna from the Amazon Basin, one of the most important sources of fresh water in the world that remains unknown in many respects.

Coelosynapha, a new genus of the subfamily Gnoristinae (Diptera: Mycetophilidae) with a circumpolar, Holarctic distribution.

BackgroundThe subfamily Gnoristinae is one of the most diverse and taxonomically difficult subfamilies of Mycetophilidae, with new species and genera being described almost every year from various parts of the world. Through inventories of fungus gnats in the Nordic Region and Russia, a genus and species new to science was discovered, yet with links back to an illustration made by the late French entomologist Loïc Matile in the 1980s. DNA barcoding aligned it with yet another species new to science, distributed across Canada and documented through The Barcode of Life Data System (BOLD) by Paul D. N. Hebert and colleagues at the BOLD team.New informationThe new Holarctic genus, Coelosynapha gen. n. is described, consisting of two new species, the Palaearctic Coelosynapha loici sp. n. and the Nearctic Coelosynapha heberti sp. n. DNA-barcodes assign the two new species to distinctly separated (8.27% p-distance) Barcode Index Numbers (BINs) which are most closely aligned to unidentified species of Mycetophilidae from South Australia and Costa Rica on BOLD. The new genus shows morphological characteristics in between the two Holarctic genera Coelosia Winnertz, 1864 and Synapha Meigen, 1818 and further shows affinity to the southern continents genus Austrosynapha Tonnoir, 1929. The Palaearctic Coelosynapha loici sp. n., for which habitat requirements are best documented, is largely restricted to pristine, old-growth conifer (mostly spruce, Picea abies ssp. obovata) forests within the boreal vegetation zone, although it is also recorded from hummock tundra along the Anadyr River in Far East Russia.

The omission of critical data in the pursuit of ‘revolutionary’ methods to accelerate the description of species

The omission of critical data in the pursuit of ‘revolutionary’ methods to accelerate the description of species

The DNA barcoding project on German Diptera: An appreciative and critical analysis with four suggestions for improving the development and reliability of DNA-based identification

The progress in constructing a DNA barcode library for German Diptera as published by Moriniere et al. (2019, Mol. Ecol. Resour. 19: 900-928) is appraised from a dipterists' perspective. The coverage of the diversity of German Diptera in terms of barcode index numbers (BINs) and identified barcodes is analysed and visualized in simple diagrams. The influence of the project setup, methodology and/or systematic effects on the emerging numbers and trends is elucidated and extensively discussed. In addition, the documentation on the species identification methods in the database is assessed. Based on this evaluation, four ways for improving the future development, utility and reliability of this DNA database and similar projects in general are identified: (1) Sample the collections of experts. This results in a greater and more reliable coverage within a limited time frame, as opposed to random collecting and relying on a posteriori identification. (2) Give priority to medically, agriculturally or ecologically important families. Addressing these gaps will meet the most pressing needs of the community and serve as a good advertisement for the usefulness and wide applicability of the DNA barcode library. (3) Allocate resources to recruiting established experts as opposed to trainees. The fact that half of the recovered BINs remained unidentified mostly results from the insufficient involvement of experts (and expert time). (4) Appropriately document the morphological identifications by experts in the database. This will allow to assess the reliability of DNA-based identifications and to prioritize conflicting identifications within a BIN accordingly.

DNA barcoding to characterize biodiversity of freshwater fishes of Egypt.

The current study represents the first molecular characterization of freshwater fish species in Egypt from two major fish resources; the River Nile and Lake Nasser. A total of 160 DNA barcodes using a 655-bp-long fragment of the mitochondrial cytochrome oxidase subunit I (COI) gene were generated from 37 species belonging to 32 genera that represent 15 families from nine orders. The studied species were identified using different molecular-based identification approaches, in addition to the morphological identification, including neighbor-joining (NJ) trees, Barcode Index Number, and Automatic Barcode Gap Discovery (ABGD). The average genetic divergence based on the Kimura two-parameter model (K2P) within orders, families, genera, and species were 0.175, 0.067, 0.02, and 0.008, respectively. The minimum and maximum K2P distance-based genetic divergences were 0.0 and 0.154, respectively. Nucleotide diversity (π) varied among families and ranged between 0.0% for families Malapteruridae, Auchenoglanididae, Schilbeidae, Anguillidae, Centropomidae and Tetraodontidae and 17% for family Cyprinidae. The current study cautions against the lack of species coverage at public databases which limits the accurate identification of newly surveyed species and recommends that multiple methods are encouraged for accurate species identification. The findings of the current study also support that COI barcode enabled effective fish species identification in River Nile and Lake Nasser. Moreover, the results of the current study will establish a comprehensive DNA barcode library for freshwater fishes along the River Nile in Egypt. Egyptian freshwater fish DNA barcodes will contribute substantially to future efforts in monitoring, conservation, and management of fisheries in Egypt.

DNA metabarcoding for biodiversity monitoring in a national park: Screening for invasive and pest species.

DNA metabarcoding was utilized for a large-scale, multiyear assessment of biodiversity in Malaise trap collections from the Bavarian Forest National Park (Germany, Bavaria). Principal component analysis of read count-based biodiversities revealed clustering in concordance with whether collection sites were located inside or outside of the National Park. Jaccard distance matrices of the presences of barcode index numbers (BINs) at collection sites in the two survey years (2016 and 2018) were significantly correlated. Overall similar patterns in the presence of total arthropod BINs, as well as BINs belonging to four major arthropod orders across the study area, were observed in both survey years, and are also comparable with results of a previous study based on DNA barcoding of Sanger-sequenced specimens. A custom reference sequence library was assembled from publicly available data to screen for pest or invasive arthropods among the specimens or from the preservative ethanol. A single 98.6% match to the invasive bark beetle Ips duplicatus was detected in an ethanol sample. This species has not previously been detected in the National Park.

Nematode biodiversity assessments need vouchered databases: A BOLD reference library for plant-parasitic nematodes in the superfamily Criconematoidea.

Nematodes are frequently cited as underrepresented in faunistic surveys using DNA barcoding with COI. This underrepresentation is generally attributed to a limited presence of nematodes in DNA databases which, in turn, is often ascribed to structural variability and high evolutionary rates in nematode mitochondrial genomes. Empirical evidence, however, indicates that many taxa are readily amplified with primer sets specifically targeted to different nematode families. Here we report the development of a COI reference library of 1726 specimens in the terrestrial plant parasitic nematode superfamily Criconematoidea. Specimens collected during an ecoregion survey of North America were individually photographed, measured, and PCR amplified to produce a 721 bp region of COI for taxonomic analysis. A neighbor-joining tree structured the dataset into 179 haplotype groups that generally conformed to morphospecies in traditional analysis or Barcode Index Numbers (BINs) in the BOLD system, although absent formal BIN membership due to insufficient overlap with the Folmer region of COI. Approximately one-third of the haplotype groups could be associated with previously described species. The geographic distribution of criconematid nematode species suggests a structure influenced by the major habitat types in the United States and Canada. All sequences collected in the ecoregion survey are deposited in BOLD.

First records raise questions: DNA barcoding of Odonata in the middle of the Mediterranean.

We present the results of the first-ever DNA barcoding study of odonates from the Maltese Islands. In total, 10 morphologically identified species were collected during a two-week long expedition in 2018. Eighty cytochrome c oxidase subunit I (COI) barcodes were obtained from the collected specimens. Intra- and interspecific distances ranged from 0.00% to 2.24% and 0.48% to 17.62%, respectively. Successful species identification based on ascribing a single morphological species to a single Barcode Index Number (BIN) was achieved for eight species (80%). In the case of two species, Ischnura genei and Anax parthenope, BINs were shared with other closely related species. The taxonomic status of I. genei is questionable and the phylogenetic relationship between A. imperator/parthenope is not clear. Further studies involving a series of adult specimens collected in a wide spatial range and nuclear markers are necessary to resolve these cases. Therefore, this dataset serves as an initial DNA barcode reference library for Maltese odonates, within a larger project: Aquatic Macroinvertebrates DNA Barcode Library of Malta.

Acheroxenylla (Collembola, Hypogastruridae), first record from the Americas with description of a new species from a Peruvian cave

A new diagnosis for Acheroxenylla Ellis, 1976 is proposed, based on new characteristics recently discovered in other species of the genus. A new species living on guano from oil bird guacharo is described and illustrated and its Barcode Index Number (BIN) from BOLD System is given. A key for the identification of the four known species is also included.

Enemy-free space and the distribution of ants, springtails and termites in the soil of one tropical rainforest

The soil fauna of tropical rainforests is difficult to study because of its extreme species richness and taxonomic impediment. Studies of multi-taxon assemblages in the soil of tropical rainforests are relatively rare and studies of interspecific interactions, such as predation, even rarer. Here we attempt to infer prey predator interactions and enemy-free space from the faunal composition of 100 litter/soil samples obtained from Barro Colorado Island in Panama during the dry and wet seasons. We focused on assemblages of ants (assigned to categories of non-predators, potential and confirmed predators), springtails and termites, which were characterized by their Barcode Index Numbers. Overall in 0.2 m3 of soil/litter we collected 2129 ants, 5592 springtails and 260 termites, which represented 80, 104 and 15 species, respectively. The faunal composition of confirmed ant predators was spatially coincident with that of Collembola. However, despite considerable seasonal shifts in the rank abundance of Collembola species, seasonal shifts of confirmed ant predators were low, resulting in a poor match of seasonal shifts between ants and their prey items. No location could be considered as being relatively free of ant enemies for springtails or termites, but the dry season supported higher prey-predator ratios than the wet season. We inferred only 4 possible prey-predator interactions, out of 7616 potential interactions in the study system. The relative dispersion of confirmed ant predators, which only weakly influenced springtail and termite assemblages, suggests low specificity in ant-prey interactions. This confirms that “brown food webs” may be structured by bottom-up effects rather than by top-down effects.

Sorting the wheat from the chaff: a review of BINs associated with groupers of Vietnam and the implications for species identification from DNA barcoding

The Epinephelidae is a marine fish family that has been the focus of worldwide taxonomical attention due to its economic value. Recent molecular-based phylogenies have improved understanding of species diversity within this family. Nonetheless, species misidentification or hybridization has led to a barcode index number (BIN) being associated with several species, which hampers a clear species identification within the BOLD system. In this study, grouper diversity in Vietnam was investigated to check the species inventory, provide a DNA barcode library for Vietnam, and reevaluate BINs associated with some species that are present in Vietnam. To this end, 157 specimens were barcoded corresponding to 30 species and 31 BINs. Nine species were new records, bringing to 49 the number of species inventoried for Vietnam. In BOLD, these species are associated with 75 BINs, 31 species being represented by more than one BIN. A careful review of these BINs, considering the present results from Vietnam, the species composition and frequency of each BIN in BOLD, and reference species sequences from phylogenetic studies, revealed those misidentified or hybrid specimens that artificially increased the number of BINs per species. After appropriate revision, 15 species still remained associated with more than one BIN. A phylogeographic analysis of these species demonstrated that most of the BINs derived from evolutionary lineages with geographic distributions that match well known biogeographic units in the Indo-Pacific. Beyond the species identification, these multiple BINs of each species can be used to track the biogeographic origin of each of the associated specimens.

Unexpected high abyssal ophiuroid diversity in polymetallic nodule fields of the northeast Pacific Ocean and implications for conservation

Abstract. The largest and commercially appealing mineral deposits can be found in the abyssal sea floor of the Clarion-Clipperton Zone (CCZ), a polymetallic nodule province, in the NE Pacific Ocean, where experimental mining is due to take place. In anticipation of deep-sea mining impacts, it has become essential to rapidly and accurately assess biodiversity. For this reason, ophiuroid material collected during eight scientific cruises from five exploration licence areas within CCZ, one area being protected from mining (APEI3, Area of Particular Environmental Interest) in the periphery of CCZ and the DISturbance and re-COLonisation (DISCOL) Experimental Area (DEA), in the SE Pacific Ocean, was examined. Specimens were genetically analysed using a fragment of the mitochondrial cytochrome c oxidase subunit I (COI). Maximum-likelihood and neighbour-joining trees were constructed, while four tree-based and distance-based methods of species delineation (automatic barcode gap discovery, ABGD; barcode index numbers, BINs; general mixed Yule–coalescent, GMYC; multi-rate Poisson tree process, mPTP) were employed to propose secondary species hypotheses (SSHs) within the ophiuroids collected. The species delimitation analyses' concordant results revealed the presence of 43 deep-sea brittle star SSHs, revealing an unexpectedly high diversity and showing that the most conspicuous invertebrates in abyssal plains have been so far considerably underestimated. The number of SSHs found in each area varied from five (IFREMER area) to 24 (BGR (Federal Institute for Geosciences and Natural Resources, Germany) area) while 13 SSHs were represented by singletons. None of the SSHs were found to be present in all seven areas while the majority of species (44.2 %) had a single-area presence (19 SSHs). The most common species were Ophioleucidae sp. (Species 29), Amphioplus daleus (Species 2) and Ophiosphalma glabrum (Species 3), present in all areas except APEI3. The biodiversity patterns could be mainly attributed to particulate organic carbon (POC) fluxes that could explain the highest species numbers found in BGR (German contractor area) and UKSRL (UK Seabed Resources Ltd, UK contractor area) areas. The five exploration contract areas belong to a mesotrophic province, while conversely the APEI3 is located in an oligotrophic province, which could explain the lowest diversity as well as very low similarity with the other six study areas. Based on these results the representativeness and the appropriateness of APEI3 to meet its purpose of preserving the biodiversity of the CCZ fauna are questioned. Finally, this study provides the foundation for biogeographic and functional analyses that will provide insight into the drivers of species diversity and its role in ecosystem function.

Gap-analysis and annotated reference library for supporting macroinvertebrate metabarcoding in Atlantic Iberia

DNA metabarcoding provides a rapid and effective identification tool of macroinvertebrate species. The accuracy of species-level assignment, and consequent taxonomic coverage, relies on comprehensive DNA barcode reference libraries, which, due to incompleteness, are currently a recognized limitation for metabarcoding applications. In this study, we assembled a comprehensive reference library of DNA barcodes for Atlantic Iberia marine macroinvertebrate species, assessed gaps in species coverage and examined data ambiguities. Initially, an Iberian species checklist for the three dominant groups of marine macroinvertebrates was compiled, comprising 2827 species (926 Annelida, 638 Crustacea and 1263 Mollusca). A total of 18162 DNA sequences of the cytochrome c oxidase subunit I barcode region (COI-5P) matching the species checklist were compiled in a BOLD dataset, where taxonomic discordances were evaluated and cases of deep intraspecific divergence flagged. Gap-analysis showed that 63% of the Iberian macroinvertebrate species still lack a DNA barcode. Coverage gaps varied considerably across taxonomic groups with Mollusca displaying the highest sequence representation in the dataset (427 species, 49% of the total number of sequences), and Crustacea the highest species coverage with 338 species barcoded (53% of the checklist). In contrast, Polychaeta displayed the lower levels of completion (288 species, 16% of the total number of sequences). In total, 1545 Barcode Index Numbers (BINs) were assigned to 1053 barcoded species, of which 66% were taxonomically concordant, 26% displayed multiple BINs and 8% were discordant. Overall, results show that there is still a large portion of marine invertebrate taxa in this region of Europe pending barcode coverage, even considering only the dominant groups. However, the most notable finding was the relevant proportion of species flagged for significant intraspecific divergence and possible hidden diversity. The annotated reference library and gap-analysis here provided can therefore contribute to prioritize marine macroinvertebrate taxa for future research efforts and barcode coverage.

DNA Barcoding for Delimitation of Putative Mexican Marine Nematodes Species

Nematode biodiversity is mostly unknown; while about 20,000 nematode species have been described, estimates for species diversity range from 0.1 to 100 million. The study of nematode diversity, like that of meiofaunal organisms in general, has been mostly based on morphology-based taxonomy, a time-consuming and costly task that requires well-trained specialists. This work represents the first study on the taxonomy of Mexican nematodes that integrates morphological and molecular data. We added eleven new records to the Mexican Caribbean nematode species list: Anticomidae sp.1, Catanema sp.1, Enoploides gryphus, Eurystomina sp.1, Haliplectus bickneri, Metachromadora sp.1, Odontophora bermudensis, Oncholaimus sp.1, Onyx litorale, Proplatycoma fleurdelis, and Pontonema cf. simile. We improved the COI database with 57 new sequences from 20 morphotypes. All COI sequences obtained in this work are new entries for the international genetic databases GenBank and BOLD. Among the studied sites, we report the most extensive species record (12 species) at Cozumel. DNA barcoding and species delineation methods supported the occurrence of 20 evolutionary independent entities and confirmed the high taxonomic resolution of the COI gene. Different approaches provided consistent results: ABGD and mPTP methods disentangled 20 entities, whereas Barcode Index Numbers (BINs) recovered 22 genetic species. Results support DNA barcoding being an efficient, fast, and low-cost method to integrate into morphological observations in order to address taxonomical shortfalls in meiofaunal organisms.