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Introduction
Biology, systematics of Nemertea and meiofauna.
Skills and Expertise
Current institution
Additional affiliations
October 2019 - present
Major Natural History Museum
Position
- Emeritus Research Zoologist
Description
- Continue research on my own time and dime, facilitate rersearch of junior colleagues.
January 1988 - October 2019
Smithsonian National Museum of Natural History
Position
- Chair
October 1982 - October 1983
Publications
Publications (138)
Phylosymbiosis, the association between the phylogenetic relatedness of hosts and the composition of their microbial communities, is a widespread phenomenon in diverse animal taxa. However, the generality of the existence of such a pattern has been questioned in many animals across the tree of life, including small‐sized aquatic invertebrates. This...
Mesopsammic polyclad members in the family Boniniidae have attracted attention in terms of their evolutionary shifts of microhabitat and their unique morphology such as a pair of pointed tentacles extending from the anterolateral margins and prostatoid organs harbouring stylets. Here, we establish a new species of this family as Boninia panamensiss...
Hemichordata has always played a central role in evolutionary studies of Chordata due to their close phylogenetic affinity and shared morphological characteristics. Hemichordates had no meiofaunal representatives until the surprising discovery of a microscopic, paedomorphic enteropneust Meioglossus psammophilus (Harrimaniidae, Hemichordata) from th...
Hemichordata has always played a central role in evolutionary studies of Chordata due to their close phylogenetic affinity and shared morphological characteristics. Neither chordates nor hemichordates had meiofaunal representatives until the surprising discovery of a microscopic, paedomorphic enteropneust Meioglossus psammophilus (Harrimaniidae, He...
Some, probably most and perhaps all, members of the phylum Nemertea are poisonous, documented so far from marine and benthic specimens. Although the toxicity of these animals has been long known, systematic studies on the characterization of toxins, mechanisms of toxicity, and toxin evolution for this group are scarce. Here, we present the first in...
The marine ribbon worm genus Tetranemertes Chernyshev, 1992 currently includes three species: the type species T. antonina (Quatrefages, 1846) from the Mediterranean Sea, T. rubrolineata (Kirsteuer, 1965) from Madagascar, and T. hermaphroditica (Gibson, 1982) from Australia. Seven new species are described: T. bifrost sp. nov. , T. ocelata sp. nov....
Phylosymbiosis, the association between the phylogenetic relatedness of hosts and the composition of their microbial communities, is a widespread phenomenon in diverse animal taxa. However, the generality of the existence of such a pattern has been questioned, and there seems evidence against its occurrence in small-sized aquatic animals, for which...
Some, probably most and perhaps all, members of the phylum Nemertea are venomous, documented so far from marine and benthic specimens. Although the toxicity of these animals has been long known, systematic studies on characterization of toxins, mechanisms of toxicity and toxin evolution for this group are relatively scarce compared to other venomou...
The underexplored intertidal ecosystems of Antarctica are facing rapid changes in important environmental factors. Associated with temperature increase, reduction in coastal ice will soon expose new ice-free areas that will be colonized by local or distant biota. To enable detection of future changes in faunal composition, a biodiversity baseline i...
The Aotearoa New Zealand Nemertea fauna is known by the 29 marine species listed in Gibson (2009) and several informal species records since Gibson (2009) (Tables 19.1, 19.2; Fig. 19.1). The current total number of recorded taxa from the New Zealand region is 33 species, including two published operational taxono- mic units (OTUs) in Gibson (2009):...
Biodiversity assessments are critical for setting conservation priorities, understanding ecosystem function and establishing a baseline to monitor change. Surveys of marine biodiversity that rely almost entirely on sampling adult organisms underestimate diversity because they tend to be limited to habitat types and individuals that can be easily su...
In July 2019 an international team of 39 senior and junior researchers from nine countries met at the University of the Azores in Ponta Delgada, São Miguel for a 10-days workshop/summer school to explore the meiofaunal biodiversity in marine sediments of
the Azores. In total, we sampled intertidal and subtidal sediments from 54 localities on 14 ma...
Background
The growing interest in mineral resources of the deep sea, such as seafloor massive sulphide deposits, has led to an increasing number of exploration licences issued by the International Seabed Authority. In the Indian Ocean, four licence areas exist, resulting in an increasing number of new hydrothermal vent fields and the discovery of...
Tetrastemma Ehrenberg, 1828, is one of the most speciose (~110 spp.) genera within the phylum Nemertea, comprising marine monostiliferans generally having four eyes. Monophyly of Tetrastemma remains open to question, having been tested to date only with 18S rRNA gene sequences targeting 13 species. Here, we examine the clade Tetrastemma with additi...
The presence of cryptic species is fairly frequent in many invertebrate groups and even more so among invertebrates with simple morphology, such as nemerteans. Consequently, the use of molecular methods for species delimitation has become a needed tool to complement morphological analyses to better recognise such species. Nemertopsis bivittata is o...
High-throughput DNA sequencing studies allow rapid and widescale investigations into complex assemblages of organisms that would otherwise remain infeasible. Recently scientists have begun to apply metagenomic sequencing (sequencing of the complete pool of DNA from a sample) to investigate microscopic animal communities. Mitochondrial genomes are a...
Whereas a few macrofaunal nemerteans were described previously from the Azores islands of Faial and Pico, a survey of marine meiofauna from littoral and shallow sublittoral sediments sampled at São Miguel Island and Santa Maria Island in the Azores yields this first report of Nemertea for those two islands, with 55 specimens, whereas a search for l...
Thirteen species of Echinoderes with nearly identical spine/tube patterns, and apparently similar tergal extensions were re-examined and compared. Based on this, redescriptions and/or emended species diagnoses are provided for Echinoderes aureus, E. dujardinii, E. gerardi, E. imperforatus, E. pacificus, E. pilosus, E. sensibilis, E. sublicarum and...
Eight new species of Duplominona (Platyhelminthes, Proseriata, Monocelididae) are described from the Pacific coast of Panama. They differ from their congeners in the detailed morphology of hard structures associated with the copulatory organ. Duplominona basidilatata n. sp. has a cirrus provided with 5–6 rows of triangular spines, 3–8 μm long, with...
Miniaturization, which is a common feature in animals, is particularly manifest in meiofauna-animals sharing peculiar phenotypic features that evolved as adaptations to the highly specialized aquatic interstitial habitat. While revealing much about the extreme phyletic diversity of meiofauna, the genome structure of meiofaunal species could also ch...
Caecidae is a species-rich family of microsnails with a worldwide distribution. Typical for many groups of gastropods, caecid taxonomy is largely based on overt shell characters. However, identification of species using shell characteristics is problematic due to their rather uniform, tubular shells, the presence of different growth stages, and a h...
Meiofauna includes an astonishing diversity of organisms, whose census is far from being complete. Most classic ecological studies have focused on hard-bodied Ecdysozoan taxa (notably Copepoda and Nematoda), whose cuticle allows determination at species-level after fixation, rather than soft-bodied, Spiralian taxa, which most often lose any diagnos...
A new species of the genus Tetrastemma Ehrenberg, 1831, T. freyae sp. nov., is described and illustrated from Hawaii and India. The description is based on light microscopy examination of the external and internal morphology, as well as on two gene markers (cytochrome c oxidase subunit I and histone H3 DNA).
The heteronemertean genus Dushia Corrêa, 1963 was established for what was identified as D. atra (Girard, 1851) (originally Meckelia atra) based on material from littoral, shallow waters in Curaçao, while the nominal species Meckelia atra was originally described from deep water off Florida Cape. In this paper, we conclude that the type species for...
Oceanic islands, characterized by high levels of endemism and distinct faunas when compared to neighbouring continents, represent natural evolutionary laboratories for biologists to understand ecological and evolutionary processes. However, most studies on oceanic islands have focused on terrestrial and marine macrofaunal organisms, and ignored mic...
Nine new species of Duplominona and one new Pseudominona (Platyhelminthes, Proseriata, Monocelididae) are described from the Caribbean coast of Panama and from Puerto Rico. Duplominona aduncospina n. sp.; D. terdigitata n. sp.; D. pusilla n. sp.; D. bocasana n. sp. (from Panama) and D. dissimilispina n. sp.; D. chicomendesi n. sp.; D. macrocirrus n...
Animals vary widely in their ability to regenerate, suggesting that regenerative ability has a rich evolutionary history. However, our understanding of this history remains limited because regenerative ability has only been evaluated in a tiny fraction of species. Available comparative regeneration studies have identified losses of regenerative abi...
Correction to:Communications Biology;https://doi.org/10.1038/s42003-018-0119-2; published online: 14 August 2018.
In the original published version of the article, the acknowledgements incorrectly omitted a statement acknowledging the availability ofpublic data through the authors’funding from the Gulf of Mexico Research Initiative. This informati...
Animals vary widely in their ability to regenerate, suggesting that regenerative abilities have a rich evolutionary history. However, our understanding of this history remains limited because regeneration ability has only been evaluated in a tiny fraction of species. Available comparative regeneration studies have identified losses of regenerative...
Research Infrastructures (RIs) are facilities, resources and services used by the scientific community to conduct research and foster innovation. LifeWatch ERIC has developed various virtual research environments, which include many virtual laboratories (vLabs) offering high computational capacity and comprehensive collaborative platforms that supp...
Accurate assessments of biodiversity are crucial to advising ecosystem-monitoring programs and understanding ecosystem function. Nevertheless, a standard operating procedure to assess biodiversity accurately and consistently has not been established. This is especially true for meiofauna, a diverse community (>20 phyla) of small benthic invertebrat...
Ototyphlonemertes is a cosmopolitan genus of meiofaunal nemerteans. Their morphological characters are insufficient to reliably identify and delimit species. Consequently, some of the species are considered cosmopolitan despite anticipated low dispersion capability of the adults and a short planktonic larval phase. Indeed, recent studies show that...
Resulting tree of species delimitation analysis in bPTP with COI sequences.
Numbers above the branches are the posterior probability of speciation events in each branch. Lactea 1 contains 24 specimens, Lactea 2 40 specimens and Pallida 15 specimens.
(TIF)
Resulting tree of species delimitation analysis in bPTP with concatenated sequences.
Numbers above the branches are the posterior probability of speciation events in each branch. Lactea 1 contains 24 specimens, Lactea 2 40 specimens and PallidaS 10 specimens.
(TIF)
Paired Φst values for COI and COX3 separated by groups and localities.
Locality abbreviations as in Fig 1.
(TIF)
List of all specimens, their geographic localization and GenBank access numbers.
Specimens from Leasi et al. 2016 are specified on the observations field.
(XLS)
Resulting tree of species delimitation analysis in GMYC with COX3 sequences.
The diagram in the upper left corner is the time at which the model infers that the threshold transition from the speciation-level events to the coalescent-level events takes place. Red branches were probably formed after the speciation events. Lactea 1 contains 29 specime...
Photomicrographs of squeezed live specimens of Pallida and Lactea morphotypes.
(A) Specimen of Pallida showing statocysts with six granules, marked with arrows. (B) Specimen of Lactea with everted proboscis showing the mid-bulb (MB).
(TIF)
Representatives of the Meidiamidae and Otomesostomidae (Platyhelminthes: Proseriata) are seldom encountered, and the monophyly and phylogenetic relationships of these families have never been assessed on molecular basis. Here, we present the first exhaustive molecular study of Proseriata at the family level, including species belonging to the gener...
Biodiversity estimations, particularly in vulnerable tropical regions, are essential to understanding ecosystem structure, function and conservation. While threats to marine and terrestrial ecosystems have fueled increased interest in biodiversity research, information on meiofauna, a key trophic and ecologic community of microscopic organisms that...
Biodiversity estimations, particularly in vulnerable tropical regions, are essential to understanding ecosystem structure, function and conservation. While threats to marine and terrestrial ecosystems have fueled increased interest in biodiversity research, information on meiofauna, a key trophic and ecologic community of microscopic organisms that...
Comparative population genetics in asexual vs. sexual species offers the opportunity to investigate the impact of asexuality on genome evolution. Here we analyse coding sequence polymorphism and divergence patterns in the fascinating Lineus ribbon worms, a group of marine, carnivorous nemerteans with unusual regeneration abilities, and in which ase...
Most meiofaunal species are known to have a broad distribution with no apparent barriers to their dispersion. However, different morphological and/or molecular methods supported patterns of diversity and distribution that may be different among taxa while also conflicting within the same group. We accurately assessed the patterns of geographic dist...
This Checklist was prepared from data excerpted from NEMERTES, the nemertean digital knowledge base system. The NEMERTES system is accessible through the NEMERTES website (http://nemertes.si.edu) hosted by the Smithsonian Institution. Making this checklist available through the website will permit it to be updated on a frequent basis as new taxa ar...
Of 45 species of nemerteans reported for the Brazilian coast, only two were recorded from Brazil's Northeast coast. Here we report seven new records for the state of Ceara, in Northeast Brazil: Tubulanus rhabdotus Correa, 1954, Carinomella cf. lactea Coe, 1905, Baseodiscus delineatus (Delle-Chiaje 1825), Cerebratulus cf. lineolatus Coe, 1905, Cereb...
The ability to regenerate new body parts is broadly distributed across animals, yet this ability varies widely among them. To understand how regeneration evolves, we need to elucidate its gains and losses across the tree of life. Surveys across whole groups allow gains and losses of regenerative ability to be mapped onto phylogenies. We used this a...
Geminate species are a powerful tool for calibrating the molecular clock in marine organisms, and their adoption is mandatory for soft-bodied taxa, which lack fossil records. The first attempt to calibrate the molecular clock in taxa belonging to meiofaunal microturbellaria (Platyhelminthes: Proseriata) based on geminate species is presented here....
A checklist of benthic ribbon worm species from the Caribbean coast of Colombia is presented, including synonyms, distributions, a photographic record, and the main morphologic characters of each species for a rapid identification. This is the first research focused broadly on nemerteans in Colombia. 54 specimens of nemerteans were hand-collected f...
Resolving the deep relationships of ancient animal lineages has proven difficult using standard Sanger-sequencing approaches
with a handful of markers. We thus reassess the relatively well-studied phylogeny of the phylum Nemertea (ribbon worms)—for
which the targeted gene approaches had resolved many clades but had left key phylogenetic gaps—by usi...
After a first bout of primarily taxonomical effort, meiofauna studies in Brazilian waters remained virtually neglected until the 1990s. At the end of the last century, taxonomical and ecological studies on meiofauna taxa were again published regularly, especially for Nematoda and Copepoda. In this issue, 18 new species are described and ten species...
Meiofauna represent one of the most abundant and diverse communities in marine benthic ecosystems. However, an accurate assessment of diversity at the level of species has been and remains challenging for these microscopic organisms. Therefore, for many taxa, especially the soft body forms such as nemerteans, which often lack clear diagnostic morph...
The phenomenon of codon usage bias is known to exist in many genomes and it is mainly determined by mutation and selection. To understand the patterns of codon usage in nemertean mitochondrial genomes, we use bioinformatic approaches to analyze the protein-coding sequences of eight nemertean species. Neutrality analysis did not find a significant c...
We compared the anatomy of the holotype of the palaeonemertean Cephalothrix simula ( Iwata, 1952 ) with that of the holotypes of Cephalothrix hongkongiensis Sundberg, Gibson and Olsson, 2003 and Cephalothrix fasciculus ( Iwata, 1952 ), as well as additional specimens from Fukue (type locality of C. simula) and Hiroshima, Japan. While there was no m...
Three new species of Protodrilus are described from the shallow Western Atlantic waters of Belize and Panama: P. smithsoni sp. nov., P. draco sp. nov. and P. hochbergi sp. nov. Protodrilus smithsoni sp. nov. resembles P. ja¨ gersteni and P. submersus from New Zealand, differing by (i) the presence of a dorsal ciliated area on segments 5�6 of males,...
Background
Many marine meiofaunal species are reported to have wide distributions, which creates a paradox considering their hypothesized low dispersal abilities. Correlated with this paradox is an especially high taxonomic deficit for meiofauna, partly related to a lower taxonomic effort and partly to a high number of putative cryptic species. Mol...
Molecular data analyzed in the present study. Museum numbers (ZSM – Bavarian State Collection of Zoology, SI – Smithsonian Institute (numbers refer to plate coordinates), AM – Australian Museum), DNA vouchers (all at ZSM) and GenBank accession numbers. Sequences retrieved from GenBank are marked with *.
Additional phylogenetic analyses of the concatenated and single-gene dataset (bootstrap values ≥ 50 given above nodes). A. Maximum parsimony analyses conducted with PAUP on the concatenated three marker dataset. B. Maximum likelihood (ML) single-gene tree of nuclear 28S rRNA. C. ML single-gene tree of mitochondrial 16S rRNA (ambiguous parts in the...
Background:
The question of how many marine species exist is important because it provides a metric for how much we do and do not know about life in the oceans. We have compiled the first register of the marine species of the world and used this baseline to estimate how many more species, partitioned among all major eukaryotic groups, may be disco...
The mitochondrial genome is important for studying genome evolution as well as reconstructing the phylogeny of organisms. Complete mitochondrial genome sequences have been reported for more than 2200 metazoans, mainly vertebrates and arthropods. To date, from a total of about 1275 described nemertean species, only three complete and two partial mit...
Figure S1. Mitochondrial gene order (protein-coding genes and rRNAs only) of Nemertea and selected lophotrochozoan species and the putative bilaterian ground pattern (according to [39]). Gene segments are not drawn to scale. All genes are transcribed from left-to-right except those in gray, which are transcribed from right to left. The adjacencies...
Table S1. Pairwise breakpoint distance matrix of mitochondrial gene orders of nemerteans, the bilaterian ground pattern and six other lophotrochozoans*
Table S2. Pairwise reversal distance matrix of mitochondrial gene orders of nemerteans, the bilaterian ground pattern and six other lophotrochozoans*
The phylogenetic relationships of selected members of the phylum Nemertea are explored by means of six markers amplified from the genomic DNA of freshly collected specimens (the nuclear 18S rRNA and 28S rRNA genes, histones H3 and H4, and the mitochondrial genes 16S rRNA and cytochrome c oxidase subunit I). These include all previous markers and re...
Understanding the evolutionary processes from recent demographic history is especially difficult for interstitial organisms
due to their poorly known natural history. In this study, the genetic variation and population history of the four Ototyphlonemertes (Diesing in Sitz ber Math Nat Kl Akad Wiss Wien 46:413–416, 1863) species were evaluated from...
We conducted a phylogeographic study of the meiofaunal nemertean Ototyphlonemertes parmula, an apparent species complex from the littoral zone of coarse-grained beaches, using a 494-bp fragment of the mitochondrial cytochrome oxidase 3 gene (cox3). Six populations from the Gulf and Atlantic coasts of Florida, two from New England, and one from the...
A glandular cushion, called the pedal aperture gland in this paper, lies adjacent and internal to each of the two mantle margins composing the pedal aperture of the soft-shelled clam Mya arenaria. Two types of glandular cells are found in the glands. The principal type (bacillary mucous cell) manufactures secretory vesicles that contain discrete pr...
List of cephalotrichids included in the analysis, localities, labcodes, collectors, haplotypes, comments on undescribe specimens and GenBank accession number.
(0.39 MB DOC)
It has been suggested that statistical parsimony network analysis could be used to get an indication of species represented in a set of nucleotide data, and the approach has been used to discuss species boundaries in some taxa.
Based on 635 base pairs of the mitochondrial protein-coding gene cytochrome c oxidase I (COI), we analyzed 152 nemertean s...
The first complete mitochondrial genome sequence for a nemertean, Cephalothrix simula, was determined by conventional and long PCR and sequencing with primer walking methods. This circular genome is 16,296 bp in size and encodes 37 genes (13 protein-coding genes, 2 ribosomal RNAs, and 22 transfer RNAs) typically found in metazoans. All genes are en...
With threats to biodiversity posed by anthropogenic impacts and global climate change, characterization of existing flora
and fauna is increasingly important, but continues to focus predominantly on easily studied taxa. In the Southern Ocean, levels
of species richness remain relatively unexplored due to remoteness and difficulties of sampling the...
A common intertidal hoplonemertean species, Amphiporus nelsoni Sanchez, 1973, from Chile is re-described based on the investigation of material from the type locality and one other locality in Chile. The species is transferred to the genus Prosorhochmus Keferstein, 1862 (Prosorhochmidae) based on the presence of a dorsal epidermal fold, i.e., “pros...
Some of the most interesting and enigmatic cnidarians are classified within the hydrozoan subclass Trachylina. Despite being relatively depauperate in species richness, the clade contains four taxa typically accorded ordinal status: Actinulida, Limnomedusae, Narcomedusae and Trachymedusae. We bring molecular data (mitochondrial 16S and nuclear smal...
Open-ocean environments provide few obvious barriers to the dispersal of marine organisms. Major currents and/or environmental gradients potentially impede gene flow. One system hypothesized to form an open-ocean dispersal barrier is the Antarctic Polar Front, an area characterized by marked temperature change, deep water, and the high-flow Antarct...
The hoplonemertean genera Prosadenoporus Burger, 1890 and Pantinonemertes Moore and Gibson, 1981 are revised and synonymized based on a morphological re-evaluation. We redefine Prosadenoporus Burger, 1890 on the basis of characters held in common by the eight species: Prosadenoporus agricola (Willemoes-Suhm, 1874) comb. nov., Prosadenoporus arenari...
