Life goes on: Spatial heterogeneity promotes biodiversity in an urbanized coastal marine ecosystem.

Both human populations and marine biodiversity are concentrated along coastlines, with growing conservation interest in how these ecosystems can survive intense anthropogenic impacts. Tropical urban centres provide valuable research opportunities because these megacities are often adjacent to mega-diverse coral reef systems. The Pearl River Delta is a prime exemplar, as it encompasses one of the most densely populated and impacted regions in the world and is located just northwest of the Coral Triangle. However, the spatial and taxonomic complexity of this biodiversity, most of which is small, cryptic in habitat and poorly known, make comparative analyses challenging. We deployed standardized settlement structures at seven sites differing in the intensity of human impacts and used COI metabarcoding to characterize benthic biodiversity, with a focus on metazoans. We found a total of 7184 OTUs, with an average of 665 OTUs per sampling unit; these numbers exceed those observed in many previous studies using comparable methods, despite the location of our study in an urbanized environment. Beta diversity was also high, with 52% of the OTUs found at just one site. As expected, we found that the sites close to point sources of pollution had substantially lower diversity (44% less) relative to sites bathed in less polluted oceanic waters. However, the polluted sites contributed substantially to the total animal diversity of the region, with 25% of all OTUs occurring only within polluted sites. Further analysis of Arthropoda, Annelida and Mollusca showed that phylogenetic clustering within a site was common, suggesting that environmental filtering reduced biodiversity to a subset of lineages present within the region, a pattern that was most pronounced in polluted sites and for the Arthropoda. The water quality gradients surrounding the PRD highlight the unique role of in situ studies for understanding the impacts of complex urbanization pressures on biodiversity.

Allopatric mosaics in the Indo-West Pacific crab subfamily Chlorodiellinae reveal correlated patterns of sympatry, genetic divergence, and genitalic disparity.

Molecular studies have revealed that many species once thought to be wide-ranging in the Indo-West Pacific contain allopatric mosaics of endemic lineages. These lineages provide compelling evidence that substantial time is needed to evolve isolating mechanisms sufficient to permit successful secondary sympatry, and that divergence is initiated in allopatry. In this context, questions arise regarding the nature, timing, and origin of isolating mechanisms that permit secondary sympatry. We present a phylogeny of the crab subfamily Chlorodiellinae which displays allopatric mosaics within species. These allopatric lineages typically do not have divergent male genitalia, while older sympatric lineages do. We tested the relationship between genetic distance (proxy for time), sympatry, and the divergence of male genitalic morphology. Our results suggest that male genitalic divergence is not involved in the initiation of speciation in chlorodielline crabs, having likely occurred only after isolation began in allopatry. However, morphological evolution of genitalia seemingly does play an important role in completing the process of speciation in these crabs.

Phylogenetic position of Bopyroides hippolytes, with comments on the rearrangement of the mitochondrial genome in isopods (Isopoda: Epicaridea: Bopyridae).

BACKGROUND: Classification of parasitic bopyrids has traditionally been based on morphological characteristics, but phylogenetic relationships have remained elusive due to limited information provided by morphological data and tendency for loss of morphological features as a result of parasitic lifestyle. Subfamily Argeiinae was separated from Bopyrinae based on morphological evidence, although the assignment of all genera has not been phylogenetically evaluated. Bopyroides hippolytes has been traditionally classified in Bopyrinae, but divergent morphological characters make this assignment questionable. To investigate the relationship of bopyrines, we sequenced the complete mitochondrial genome of B. hippolytes and four mitochondrial genes of two other Bopyrinae. RESULTS: The phylogenetic trees based on separate and combined cox1and 18S sequence data recovered Bopyridae as robustly monophyletic, but Bopyrinae as polyphyletic. Bopyroides hippolytes was a close sister to Argeia pugettensis, type species to Argeiinae. Mitochondrial phylogenomics also suggested that B. hippolytes was close to Argeiinae. We also found a novel gene order in B. hippolytes compared to other isopods. CONCLUSIONS: Bopyroides hippolytes should be excluded from the Bopyrinae and has a close affinity with Argeia pugettensis based on molecular and morphological data. The conserved syntenic blocks of mitochondrial gene order have distinctive characteristics at a subordinal level and may be helpful for understanding the higher taxonomic level relationships of Isopoda.

Stasis and diversity in living fossils: Species delimitation and evolution of lingulid brachiopods.

The Lingulidae are often considered living fossils, because they have shown little morphological change since the Paleozoic. Limited morphological variation has also made the taxonomic study of living lingulids challenging. We investigated species diversity and phylogenetic relationships of extant lingulids and show that they are substantially more diverse than realized, demonstrating that morphological stasis was commonly accompanied by speciation. Species delimitation based on cytochrome c oxidase subunit I (COI) gene sequences from 194 specimens sampled from East Asia, Australia, Oceania, and the Americas suggested 14-22 species in the lingulids (9-17 species in Lingula and 4-5 species in Glottidia), in contrast to the 11-12 species currently recognized globally in the family. Four-gene phylogenetic analyses supported the sister relationship between Lingula and Glottidia. Within Lingula, L. adamsi, which possesses large, brownish shells, was recovered as sister to all remaining Lingula species, which have more or less greenish shells. Within the greenish Lingula clade, the 'L. anatina' complex was sister to the clade that includes the 'L. reevei' complex. The 'L. anatina' complex was further separated into two major clades with partly separate ranges centered on (i) temperate East Asia, and (ii) the tropical west-central Pacific. Within Glottidia, Pacific species were nested within Atlantic species. Time-calibrated phylogenetic analyses suggested that Lingula likely originated in the early Cretaceous contrary to a previously proposed hypothesis advocating a Cenozoic origin. The separation of Lingula and Glottidia appears to date from the Mesozoic, not from the Carboniferous, contrary to a previous hypothesis. Overall, our results uncovered substantial cryptic diversity in lingulids, which will form the basis for conservation and further taxonomic revision.

Two new species and a new record of Bopyrinae (Isopoda: Bopyridae) infesting Alpheidae and Hippolytidae, with comments on the genus Bopyrina Kossmann, 1881.

Two new bopyrids, Bopyrinina articulata n. sp. and Bopyrinella asymmetrica n. sp. are described from French Polynesia, the Red Sea, and the Philippines. Bopyrinina articulata n.sp. infests Salmoneus cf. gracilipes Miya, and is distinguishable from other species of this genus by the structure of the maxilliped, pleopods and oostegite 1. Bopyrinella asymmetrica n. sp. is most similar to Bopyrinella albida Shiino, 1958, but females differ from that species because all pereomeres on the short side have round dorsolateral bosses and its pleotelson is greatly distorted. Bopyrina ocellata (Czerniavsky, 1868) is newly recorded from the Western Atlantic, from Florida, USA. Review of the species of Bopyrina revealed that B. choprai Nierstrasz & Brender à Brandis, 1929 and B. sewelli Chopra, 1930 are intermediate in morphology between Bopyrina and Schizobopyrina, the taxonomic assignment of these two species needs further evaluation. Keys to Bopyrinella Nierstrasz & Brender à Brandis, 1925 and Bopyrina Kossmann, 1881 are presented. Hosts and distributions of the seven species of Bopyrinella are summarized.

Phylogenomics, life history and morphological evolution of ophiocomid brittlestars.

Brittlestars in the family Ophiocomidae are large and colourful inhabitants of tropical shallow water habitats across the globe. Here we use targeted capture and next-generation sequencing to generate robust phylogenomic trees for 39 of the 43 species in order to test the monophyly of existing genera. The large genus Ophiocoma, as currently constituted, is paraphyletic on our trees and required revision. Four genera are recognised herein: an expanded Ophiomastix (now including Ophiocoma wendtii, O. occidentalis, O. endeani, O. macroplaca, and Ophiarthrum spp), Ophiocomella (now including the non-fissiparous Ophiocoma pumila, aethiops and valenciae) and Breviturma (now including Ophiocoma pica, O. pusilla, O. paucigranulata and O. longispina) and a restricted Ophiocoma. The resulting junior homonym Ophiomastix elegans is renamed O. brocki. The genus Ophiomastix exhibits relatively high rates of morphological disparity compared to other lineages. Ophiomastix flaccida and O. (formerly Ophiarthrum) pictum have divergent mitochondrial genomes, characterised by gene-order rearrangements, strand recoding, enriched GT base composition, and a corresponding divergence of nuclear mitochondrial protein genes. The new phylogeny indicates that larval and developmental transitions occurred rarely. Larval culture trials show that species with abbreviated lecithotrophic larval development occur only within Ophiomastix, although the possible monophyly of these species is obscured by the rapid early radiation within this genus. Asexual reproduction by fission is limited to one species-complex within Ophiocomella, also characterised by elevated levels of allelic heterozygosity, and which has achieved a relatively rapid global distribution. The crown ages of the new genera considerably predate the closure of the Tethyan seaway and all four are distributed in both the Atlantic and Indo-Pacific Oceans. Two species pairs appear to reflect the closure of the Panama Seaway, although their fossil-calibrated node ages (12-14 ±â€¯6 my), derived from both concatenated sequence and multispecies coalescent analyses, considerably predate the terminal closure event. Ophiocoma erinaceus has crossed the East Pacific barrier and is recorded from Clipperton Island, SW of Mexico.

Molecular phylogeny of extant Holothuroidea (Echinodermata).

Sea cucumbers (Holothuroidea) are a morphologically diverse, ecologically important, and economically valued clade of echinoderms; however, the understanding of the overall systematics of the group remains controversial. Here, we present a phylogeny of extant Holothuroidea assessed with maximum parsimony, maximum likelihood, and Bayesian approaches using approximately 4.3kb of mt- (COI, 16S, 12S) and nDNA (H3, 18S, 28S) sequences from 82 holothuroid terminals representing 23 of the 27 widely-accepted family-ranked taxa. Currently five holothuroid taxa of ordinal rank are accepted. We find that three of the five orders are non-monophyletic, and we revise the taxonomy of the groups accordingly. Apodida is sister to the rest of Holothuroidea, here considered Actinopoda. Within Actinopoda, Elasipodida in part is sister to the remaining Actinopoda. This latter clade, comprising holothuroids with respiratory trees, is now called Pneumonophora. The traditional Aspidochirotida is paraphyletic, with representatives from three orders (Molpadida, Dendrochirotida, and Elasipodida in part) nested within. Therefore, we discontinue the use of Aspidochirotida and instead erect Holothuriida as the sister group to the remaining Pneumonophora, here termed Neoholothuriida. We found four well-supported major clades in Neoholothuriida: Dendrochirotida, Molpadida and two new clades, Synallactida and Persiculida. The mapping of traditionally-used morphological characters in holothuroid systematics onto the phylogeny revealed marked homoplasy in most characters demonstrating that further taxonomic revision of Holothuroidea is required. Two time-tree analyses, one based on calibrations for uncontroversial crown group dates for Eleutherozoa, Echinozoa and Holothuroidea and another using these calibrations plus four more from within Holothuroidea, showed major discrepancies, suggesting that fossils of Holothuroidea may need reassessment in terms of placing these forms with existing crown clades.

The Global Invertebrate Genomics Alliance (GIGA): developing community resources to study diverse invertebrate genomes.

Over 95% of all metazoan (animal) species comprise the "invertebrates," but very few genomes from these organisms have been sequenced. We have, therefore, formed a "Global Invertebrate Genomics Alliance" (GIGA). Our intent is to build a collaborative network of diverse scientists to tackle major challenges (e.g., species selection, sample collection and storage, sequence assembly, annotation, analytical tools) associated with genome/transcriptome sequencing across a large taxonomic spectrum. We aim to promote standards that will facilitate comparative approaches to invertebrate genomics and collaborations across the international scientific community. Candidate study taxa include species from Porifera, Ctenophora, Cnidaria, Placozoa, Mollusca, Arthropoda, Echinodermata, Annelida, Bryozoa, and Platyhelminthes, among others. GIGA will target 7000 noninsect/nonnematode species, with an emphasis on marine taxa because of the unrivaled phyletic diversity in the oceans. Priorities for selecting invertebrates for sequencing will include, but are not restricted to, their phylogenetic placement; relevance to organismal, ecological, and conservation research; and their importance to fisheries and human health. We highlight benefits of sequencing both whole genomes (DNA) and transcriptomes and also suggest policies for genomic-level data access and sharing based on transparency and inclusiveness. The GIGA Web site (http://giga.nova.edu) has been launched to facilitate this collaborative venture.

Revision of the genus Phyrella (Holothuroidea: Dendrochirotida) with the description of a new species from Guam.

Recently collected material from Australia, Japan and Guam allowed us to revise Phyrella and describe Phyrella mookiei sp. nov. We redefine the genus based on combined morphological and molecular analyses. Phyrella unlike most dendrochirotids eviscerate posteriorly. The number of tentacles is variable (14-20), as is the degree of fragmentation of the calcareous ring, calling into question the separation of Phyllophorinae and Semperiellinae, and suggest that Semperiella and Thyonidiella are synonymous with Phyrella. We recognize five species in Phyrella (Phyllophorus trapezus Clark, 1932, Phyllophorus fragilis Mitsukuri & Ohshima, 1912 (synonymized with Thyonidiella oceana Heding & Panning, 1954), Phyllophorus thyonoides Clark, 1938, Semperiella drozdovi Levin & Stepanov, 1999, and Phyrella mookiei), assign three others provisionally (Lipotrapeza ambigua Cherbonnier, 1988 (synonymized with Phyllophorus contractura Cherbonnier, 1988 and Thyonidiella cherbonnieri Rowe & Richmond, 2004), Phyllophorus bedoti Koehler, 1895, and Orcula tenera Ludwig, 1875), considering the last two species inquirenda. Phyrella aculeatus (Ludwig, 1894), is transferred to Euthyonidiella. Orcula (Phyllophorus?) dubia Bedford, 1899, Thyonidiella exigua Cherbonnier, 1988 and Thyonidiella kungi O'Loughlin, 2012 are provisionally transferred to Phyllophorus sensu lato, the first is considered species inquirenda. Molecular phylogenetic analysis recovers a well-supported Phyrella, but suggests that some genera and subfamilies of Phyllophoridae are not monophyletic.

Ctenophora: Illustrated Guide and Taxonomy.

Ctenophores or comb jellies represent the first diverging lineage of extant animals - sister to all other Metazoa. As a result, they occupy a unique place in the biological sciences. Despite their importance, this diverse group of marine predators has remained relatively poorly known, with both the species and higher-level taxonomy of the phylum in need of attention. We present a checklist of the phylum based on a review of the current taxonomic literature and illustrate their diversity with images. The current classification presented remains substantially in conflict with recent phylogenetic results, and many of the taxa are not monophyletic or untested. This chapter summarizes the existing classification focusing on recognized families and genera with 185 currently accepted, extant species listed. We provide illustrative examples of ctenophore diversity covering all but one of the 33 families and 47 of the 48 genera, as well as about 25-30 undescribed species. We also list the 14 recognized ctenophore fossil species and note others that have been controversially attributed to the phylum. Analyses of unique ctenophore adaptations are critical to understanding early animal evolution and adaptive radiation of this clade of basal metazoans.

A remarkable new crab-like hermit crab (Decapoda: Paguridae) from French Polynesia, with comments on carcinization in the Anomura.

Patagurus rex gen. et sp. nov., a deep-water pagurid hermit crab, is described and illustrated based on a single specimen dredged from 400 m off Moorea, Society Islands, French Polynesia. Patagurus is characterized by a subtriangular, vaulted, calcified carapace, with large, wing-like lateral processes, and is closely related to two other atypical pagurid genera, Porcellanopagurus Filhol, 1885 and Solitariopagurus Türkay, 1986. The broad, fully calcified carapace, calcified branchiostegites, as well as broad and rigidly articulated thoracic sternites make this remarkable animal one of the most crab-like hermit crabs. Patagurus rex carries small bivalve shells to protect its greatly reduced pleon. Carcinization pathways among asymmetrical hermit crabs and other anomurans are briefly reviewed and discussed.

Integrative species delimitation in the common ophiuroid Ophiothrix angulata (Echinodermata: Ophiuroidea): insights from COI, ITS2, arm coloration, and geometric morphometrics.

Ophiothrix angulata (Say, 1825) is one of the most common and well-known ophiuroids in the Western Atlantic, with a wide geographic and bathymetric range. The taxonomy of this species has been controversial for a century because of its high morphological variability. Here we integrate information from DNA sequence data, color patterns, and geometric morphometrics to assess species delimitation and geographic differentiation in O. angulata. We found three deeply divergent mtDNA-COI clades (K2P 17.0-27.9%). ITS2 nuclear gene and geometric morphometrics of dorsal and ventral arm plates differentiate one of these lineages, as do integrative species delineation analyses, making this a confirmed candidate species.

Diversity and Distribution of Fiddler Crabs (Crustacea: Brachyura: Ocypodidae) around the Arabian Sea.

Nine species of fiddler crabs (Crustacea: Ocypodidae: Gelasiminae) are known from the Arabian Sea and adjacent waters (Red Sea, Gulf of Aden, Gulf of Oman and Arabian/Persian Gulf): five species of Austruca, one Cranuca, two Gelasimus and one Tubuca. COI sequence data match morphological species boundaries and shows high connectivity within each. The fauna is highly endemic, with three species of Austruca (A. albimana, A. iranica and A. sindensis) confined to this region, and four others restricted to the Indian Ocean. restricted to the Indian Ocean. Austruca albimana and A. iranica speciated locally and now have narrowly overlapping ranges in Oman. Our results confirm the westernmost distributions of Austruca annulipes and Tubuca alcocki are Pakistan and the Red Sea, respectively. A key for the nine species is also provided to help identification.

Paleozoic origins of cheilostome bryozoans and their parental care inferred by a new genome-skimmed phylogeny.

Phylogenetic relationships and the timing of evolutionary events are essential for understanding evolution on longer time scales. Cheilostome bryozoans are a group of ubiquitous, species-rich, marine colonial organisms with an excellent fossil record but lack phylogenetic relationships inferred from molecular data. We present genome-skimmed data for 395 cheilostomes and combine these with 315 published sequences to infer relationships and the timing of key events among c. 500 cheilostome species. We find that named cheilostome genera and species are phylogenetically coherent, rendering fossil or contemporary specimens readily delimited using only skeletal morphology. Our phylogeny shows that parental care in the form of brooding evolved several times independently but was never lost in cheilostomes. Our fossil calibration, robust to varied assumptions, indicates that the cheilostome lineage and parental care therein could have Paleozoic origins, much older than the first known fossil record of cheilostomes in the Late Jurassic.

Conventional taxonomy obscures deep divergence between Pacific and Atlantic corals.

Only 17% of 111 reef-building coral genera and none of the 18 coral families with reef-builders are considered endemic to the Atlantic, whereas the corresponding percentages for the Indo-west Pacific are 76% and 39%. These figures depend on the assumption that genera and families spanning the two provinces belong to the same lineages (that is, they are monophyletic). Here we show that this assumption is incorrect on the basis of analyses of mitochondrial and nuclear genes. Pervasive morphological convergence at the family level has obscured the evolutionary distinctiveness of Atlantic corals. Some Atlantic genera conventionally assigned to different families are more closely related to each other than they are to their respective Pacific 'congeners'. Nine of the 27 genera of reef-building Atlantic corals belong to this previously unrecognized lineage, which probably diverged over 34 million years ago. Although Pacific reefs have larger numbers of more narrowly distributed species, and therefore rank higher in biodiversity hotspot analyses, the deep evolutionary distinctiveness of many Atlantic corals should also be considered when setting conservation priorities.

Three new species of Scyracepon Tattersall, 1905 (Isopoda: Bopyridae) from Pacific islands, with comments on the rarity of bopyrids parasitizing brachyurans.

Three new species of the bopyrid genus Scyracepon Tattersall, 1905 are described from crabs collected on Pacific Islands: Scyracepon polynesiensis n. sp. from the Society Islands, S. pseudoliomerae n. sp. from the Mariana Islands, and S. biglobosus n. sp. from the Line Islands. The first two were found infesting Xanthias lamarckii and Pseudoliomera sp. (Xanthidae), a new host family for species of Scyracepon, and the last was found parasitizing Schizophrys aspera (Majidae). Scyracepon now includes 11 species, all but one known from single collections, infesting 12 host species in 9 brachyuran families. The discovery of three new species, each rare, suggests that crab parasites are undersampled, and further suggests that the low relative diversity of bopyrids known from brachyurans may partly reflect this undersampling. Keys to all species of Scyracepon and to all 31 genera of Keponinae are provided.

Three new species of abdominal shrimp parasites (Crustacea: Isopoda: Bopyridae: Hemiarthrinae) from the Indo-West Pacific.

Three new species of the parasitic isopod subfamily Hemiarthrinae Markham, 1972 are described. Allodiplophryxus unilateralis n. sp. is described from Western Australia, infesting the palaemonid shrimp Jocaste lucina (Nobili, 1901), and females differ from the only other species in the genus in possessing six pleomeres, an asymmetrical first oostegite and pleopods restricted to the short side of the body. Loki athanus n. sp. is described from Madagascar, infesting the alpheid shrimp Athanas parvus de Man, 1910, and females differ from the only other species in the genus in possessing well-developed lateral plates on pleomere 4 and four pairs of uniramous pleopods. Hemiarthrus alphei n. sp. is described from French Polynesia, infesting the alpheid shrimp Alpheus crinitus Dana, 1852, and females differ from the four other known Hemiarthrus species in having pleomeres with well-developed, symmetrical lateral plates, a barbula with three pairs of projections and a pointed pleotelson. Keys to species of Hemiarthrus and all genera of the Hemiarthrinae are presented.

World Travelers: DNA Barcoding Unmasks the Origin of Cloning Asteroid Larvae from the Caribbean.

AbstractThe identity of wild cloning sea star larvae has been a mystery since they were first documented in the Caribbean. The most commonly collected cloning species was thought to belong to the Oreasteridae, on the basis of similarity with sequences from Oreaster reticulatus and Oreaster clavatus. This larval form has recently been linked to a rare benthic juvenile. As part of two larger DNA barcoding projects, we collected cloning asteroid larvae from the Caribbean coast of Panama and compared them to a large reference database of tropical echinoderms. Morphological and DNA barcode data from the cytochrome c oxidase subunit I gene demonstrated that Panamanian larvae belonged to the same operational taxonomic unit as those recovered in previous studies of cloning larvae from the Caribbean. Much to our surprise, sequences from these larvae clearly identified them as belonging to Valvaster striatus, a species typically considered to be endemic to the Indo-West Pacific. A lineage of Mithrodia clavigera that occurs in both the Caribbean and the Indo-West Pacific also has cloning larvae, suggesting that this unusual life history has allowed larvae to pass around the Cape of Good Hope and the Benguela upwelling region, which is a barrier to dispersal for most tropical marine invertebrates.

Eggs sunny-side up: A new species of Olea, an unusual oophagous sea slug (Gastropoda: Heterobranchia: Sacoglossa), from the western Atlantic.

Nearly all of the recognized species of sea slugs in clade Sacoglossa (about 300 taxa) are herbivorous, using a uniseriate radula in suctorial feeding. The only exceptions are a pair of monotypic genera in the ceratiform family Limapontiidae: Olea Agersborg, 1923 from the northeastern Pacific, and Calliopaea d'Orbigny, 1837 from the northeastern Atlantic coast of Europe and the Mediterranean. Both genera feed on the eggs of other heterobranchs, notably cephalaspideans, and lack cerata on the anterior dorsum. Major differences are that C. bellula d'Orbigny, 1837 has more cerata than O. hansineensis Agersborg, 1923, a more typical radula with ascending and descending rows of fully-formed teeth, and a much longer penial stylet. Here, we describe a new egg-eating sacoglossan species from the subtropical Gulf of Mexico coast of Florida, U.S.A. Phylogenetic relationships inferred from analyses of a four-gene dataset including 219 sacoglossan species indicated the new taxon (O. hensoni n. sp.) belongs to Olea. The generic placement of the new species is also supported by its highly reduced radula and comparatively short penial stylet. A full description of the reproductive, digestive, and nervous systems is also provided. Finding a new Olea species in the warm waters of the western Atlantic was surprising, given the genus was previously known only from the cold northern Pacific, and suggests further diversity in oophagous sacoglossans may await discovery.

DNA barcoding: error rates based on comprehensive sampling.

DNA barcoding has attracted attention with promises to aid in species identification and discovery; however, few well-sampled datasets are available to test its performance. We provide the first examination of barcoding performance in a comprehensively sampled, diverse group (cypraeid marine gastropods, or cowries). We utilize previous methods for testing performance and employ a novel phylogenetic approach to calculate intraspecific variation and interspecific divergence. Error rates are estimated for (1) identifying samples against a well-characterized phylogeny, and (2) assisting in species discovery for partially known groups. We find that the lowest overall error for species identification is 4%. In contrast, barcoding performs poorly in incompletely sampled groups. Here, species delineation relies on the use of thresholds, set to differentiate between intraspecific variation and interspecific divergence. Whereas proponents envision a "barcoding gap" between the two, we find substantial overlap, leading to minimal error rates of approximately 17% in cowries. Moreover, error rates double if only traditionally recognized species are analyzed. Thus, DNA barcoding holds promise for identification in taxonomically well-understood and thoroughly sampled clades. However, the use of thresholds does not bode well for delineating closely related species in taxonomically understudied groups. The promise of barcoding will be realized only if based on solid taxonomic foundations.