Phoronids Research Articles

First record of Phoronopsis (Phoronida) from Japan, with a description of Phoronopsiscalifornica Hilton, 1930 from Okinawa.

Phylum Phoronida currently contains two genera, Phoronis Wright, 1856 and Phoronopsis Gilchrist, 1907, with approximately thirteen speices. Phoronida is distributed worldwide, ranging from northern Europe to southern New Zealand and also from intertidal to 400 m depths. From Japanese waters, four species of Phoronis have been reported, viz. Phoronisijimai Oka, 1897, Phoronisaustralis Haswell, 1883, Phoronispsammophila Cori, 1889 and Phoronisemigi Hirose et al., 2014. We describe the morphology of Phoronopsiscalifornica Hilton, 1930, based on five specimens collected at a sandy-mud habitat in Nago Bay and Oura Bay, Okinawa, Japan. We examined the internal anatomy by serial paraffin sections. We also examined the genetic distance of Japanese specimens from the other phoronid sequences in GenBank. This is the first record of Phoronopsis from Japanese waters and the fifth species record of phoronids in addition to the previously recorded four species of Phoronis.

Spatial compartmentalisation of bacteria in phoronid microbiomes

The phylum Phoronida comprises filter-feeding invertebrates that live in a protective tube sometimes reinforced with particulate material from the surrounding environments. Animals with these characteristics make promising candidate hosts for symbiotic bacteria, given the constant interactions with various bacterial colonizers, yet phoronids are one of the very few animal phyla with no available microbiome data whatsoever. Here, by sequencing the V4 region of the 16S rRNA gene, we compare bacterial microbiomes in whole phoronids, including both tube and living tissues, with those associated exclusively to the isolated tube and/or the naked animal inside. We also compare these communities with those from the surrounding water. Phoronid microbiomes from specimens belonging to the same colony but collected a month apart were significantly different, and bacterial taxa previously reported in association with invertebrates and sediment were found to drive this difference. The microbiomes associated with the tubes are very similar in composition to those isolated from whole animals. However, just over half of bacteria found in whole specimens are also found both in tubes and naked specimens. In conclusion, phoronids harbour bacterial microbiomes that differ from those in the surrounding water, but the composition of those microbiomes is not stable and appears to change in the same colony over a relatively short time frame. Considering individual spatial/anatomical compartments, the phoronid tube contributes most to the whole-animal microbiome.

A Microsporidian Infection in Phoronids (Phylum Phoronida): Microsporidium phoronidi n. sp. from a Phoronis embryolabi.

Microsporidia-like spores (2.0-3.0×1.3-1.5μm) were discovered upon examination of histological sections taken from Phoronis embryolabi Temereva, Chichvarkhin 2017 found inhabiting burrows of shrimps Nihonotrypeae japonica (Decapoda, Callianassidae) from the Sea of Japan, Russia. Ultrastructural examination of spores revealed one nucleus and a uniform polar filament of 7-11 coils. Representatives of the phylum Phoronida have never been recorded as hosts of microsporidia. Parasites developed in vasoperitoneal tissue and caused formation of multinucleate syncytia. Basing on unique host and fine morphology, we assign the novel finding to Microsporidium phoronidi n. sp. and place provisionally in the collective genus Microsporidium.

The evidence of metamery in adult brachiopods and phoronids

The evidence of metamery in adult brachiopods and phoronids

Ventral nerve cord in Phoronopsis harmeri larvae

The nervous system organization is considered a phylogenetically important character among metazoans. The phylum Phoronida is included in a supraphyletic taxon known as Lophotrochozoa. Many lophotrochozoans possess a metameric ventral nerve cord as adults or larvae. Phoronids do not exhibit external metamery either as larvae or as adults. The current study describes the ventral nerve cord in the young larva of Phoronopsis harmeri. This structure is apparent both in the serotonergic and FMRF-amidergic nervous system in young larvae. The ventral nerve cord extends from the mouth to the tentacular ridge. Both serotonergic and FMRF-amidergic components consist of two ventrolateral nerves, each with several unipolar neurons. The ventrolateral nerves connect to each other by means of thin repetitive transversal nerves ("commissures"). The abundance of neurons and nerves in the epidermis of the oral field of actinotrocha larva likely reflects the importance of this area in collection of food particles. The ventral nerve cords of the actinotrocha and the metatrochophore differ in their positions with respect to ciliated bands: the cord is located between the preoral and postoral ciliated bands in the actinotrocha but between the postoral ciliated band and telotroch in the metatrochophore. The presence of the ventral nerve cord, which contains repetitive elements (neurons and "commissures"), in the early development of P. harmeri may recapitulate some stages of nervous system development during phoronid phylogeny. The larval nervous system does not contain nervous centers under the tentacular ridge that can correlate with the catastrophic metamorphosis and unique body plan of phoronids.

The presence of Phoronis australis (Phoronida) in southern Italian waters

Biogeographia vol. XXX - 2011 (Pubblicato il 23 dicembre 2011) La Biogeografia della Sici/ia The presence of Plzoroms auszfralis (Phoronida) in southern Italian waters ANDREA COSENTINO, SALVATORE GIACOBBE, ANDREA POTOSCHI Dzpartimento di Biologia Animale ea’ Ecologia Marina, Universita degli Studi dzq Messina, Salita Sperone 31, 901665. Agata, Messina (Italy) e—maz'l: sgz'ac0bbe@unz'me. it Key words: Phoronida, symbiosis, dispersion, Mediterranean Sea. SUMMARY Since the beginning of the 19905 records of the Phoronida species in the Mediterranean were limited to P/aoro- nis muelleri Selys-Longchamps, 1903, P. /Jippocrepia Wright, 1856 and P. psammop/yila Cori, 1889. Thereafter, P. azutrali: Haswell, 1883, P. oz/ali: Wright, 1856, and three species belonging to the genus Plmronopsis (P. all7omac— ulata Gilchrist, 1907, P. calzfbrnica Hilton, 1930 and P. /aarmeri Pixell, 1912) were recorded. P. azzstralis, distributed in the Indo—Pacif1c and in the south-eastern Atlantic Oceans, was first recorded in the Mediterranean area along the coasts of Spain and Greece. Data reported in this paper have been collected since 2003 and show the current distribution of P. azzstralis in southern Italian waters. Video-photographic records and the examination of the anatomical and ecological features of fifty specimens obtained by means of diving surveys confirmed the presence of the species. Stable populations of P. australir were observed at Milazzo, on the isle of Salina (Sicily) and also on the Cal- abrian side of the Strait of Messina. The species, which prefers to inhabit the mucous tube of Ceriant/Jus spp., was always found in association with C. memlzranacezts (Spallanzani, 1784). As it has happened with other warm-tem- perate species, P. amtralis could have widened its distribution due to the warming of Mediterranean coastal waters, either through the Suez Canal and the Strait of Gibraltar (double-source hypothesis) or only through the latter (sin- gle-source hypothesis). The latter is supported by the earlier occurrence of the population on the Spanish coasts and its relative abundance compared to the Levantine coasts. In both cases, the present record supports the role of the Strait of Messina as a “biogeographic bridgehead” on the scale of the Mediterranean basin. INTRODUCTION The phylum Phoronida comprises only two genera, Plzoronis and Pl70ron0p— sis, with ten Valid species, mostly with Wide geographic distributions. Nine species have been recorded from European waters (Emig et al., 2000), eight of which were also present in the Mediterranean: Pkoronis mulleri Selys—Longchamps, 1903, P. ovalis Wright, 18 56, P. psammopbila Cori, 1889, Plaoronopsis alba- maculata Gilchrist, 1907, P. calzfi2mz'ca Hilton, 1930 and P. /aarmeri Pixell, 1912, which dwell on sandy or muddy bottoms, whereas P. australis Haswell, 1883 and P. bippocrepia Wright, 1856 are hard substrate borers. Up to date the check- list of the Italian marine fauna (http://wwW.sibm.it/CHECKLIST/princi-

An unexpectedly sophisticated, V-shaped spermatozoon in Demospongiae (Porifera): reproductive and evolutionary implications

The demosponge Crambe crambe shows a peculiar spermatogenesis, hard to be reconciled with the basal position of sponges in the animal phylogeny. Early spermatogenesis stages showed most of the simple features expected in sponges. However, spermiogenesis departed from the anticipated process. Spermatids lengthened remarkably, forming a deep cytoplasmic pit around the cilium insertion, with the proximal axoneme bending to produce a V-shaped spermatozoon surprisingly similar to that known in the phylum Phoronida. The cytology was unexpectedly complex, with a needle-like nucleus of helically condensed chromatin, a conical acrosome with a subacrosomal rod, and a mitochondrion connected to the basal body by striated rootlets. These findings establish that the spermatozoon of broad-casting demosponges occurs in two structural categories (‘primitive’ and ‘modified’ type). This dualistic condition must necessarily have pre-dated the evolutionary apparition of higher metazoans, if we are to keep regarding sponges as the most primitive animals. We hypothesize that internal fertilization in C. crambe– and incidentally other demosponges – may depart from the general model assumed for spermcasting sponges. The V-shape of this spermatozoon suggests a design to favour autonomous penetration through the dense mesohyl to reach the oocytes, rather than engulfment and transportation by carrier cells towards the oocyte. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 413–426.

The systematics and evolution of the phylum Phoronida

The systematics and evolution of the phylum Phoronida

THE FIRST REPORT OF PHORONIS SP. (PHORONIDA) IN RED ABALONE (HALIOTIS RUFESCENS) IN CHILE

Abstract Various red abalone shells (Haliotis rufescens) taken from Chiloe, X Region, Chile, were examined revealing an enormous amount of vermiform organisms identified as phoronides (Phylum Phoronida) belonging to the genus Phoronis. These individuals have an extended vermiform body not divided into segments, but its upper extreme shows a crown of tentacles shaped in a circular ring (that is the reason why they could be confused with Sabellidae polychaetes, although they do not have segmented body and lack bristles). These are found in the interior of very fragile quitinous tubes. Only Phoronis ovalis has been recorded in Chile found perforating the shell of Chilean abalone, Concholepas concholepas, in samples from the coastal rocks of Mehuin, Valdivia (Arenas 1972).

Methods of ciliary filter feeding in adult Phoronis muelleri (phylum Phoronida) and in its free-swimming actinotroch larva

Microscope-video recordings were used to describe basic characteristics of particle capture in adult Phoronis muelleri and in its actinotroch larva. The larva captures food particles by means of close interplay between the tentacles and the oral hood. Suspended particles in the incoming water flow set up by the lateral "pump" cilia on the tentacles approach the tentacles with a velocity of about 1.5 mm s–1. Near the tentacles, the particles are stopped by the stiff sensory laterofrontal cilia acting as a mechanical sieve. Simultaneous with stoppage of a particle, the oral hood is rapidly lifted so that water from the surrounding area flows in to occupy the volume created under the hood. Due to the proximity of the tentacle with the arrested particle, this suction will draw the particle away from the laterofrontal cilia into the increased space under the oral hood with a velocity of about 0.6 mm s–1 before it is subsequently carried to the mouth. If a particle is stopped near the tip of a tentacle this may trigger a tentacle flick, with a tip velocity of about 5–7 mm s–1, which brings the particle down toward the lifting edge of the hood. A stopped particle may cause a local disruption of the metachronism of the lateral cilia for about 0.14 s. Likewise in the adult, when an incoming particle with a velocity of about 1.6 mm s–1 is stopped near the tip of a tentacle this triggers a flick, which brings the particle down towards the mouth. The duration of the active flick phase is about one-tenth of the flick cycle. Only when a particle is stopped on the outer part of a tentacle is a flick triggered. Otherwise the particle is either transported down along the frontal surface of the tentacle by means of the frontal cilia, or transferred into the downward current created by the lophophore. The metachronal wave velocity is about 0.25 mm s–1, the wavelength about 12 µm, and hence the ciliary beat frequency about 21 Hz (at ~16°C). Essential features of the filter-feeding process in both actinotroch larvae and adult P. muelleri reported here resemble the ciliary-sieving process described for bryozoans in recent years. It should be pointed out that the stiff, mechanosensory laterofrontal cilia may be a decisive factor for understanding ciliary upstream collecting, also in pterobranchs and brachiopods in which sensory laterofrontal cilia are present.

Regional Specification during Embryogenesis in the Craniiform Brachiopod Crania anomala

A fate map has been constructed for the embryo of Crania. The animal half of the egg forms the ectodermal epithelium of the larva's apical lobe. The vegetal half of the egg forms endoderm, mesoderm, and the ectoderm of the mantle lobe. The vegetal pole is the site of gastrulation; this site becomes the posterior ventral region of the mantle lobe of the larva. The plane of the first cleavage goes through the animal–vegetal axis of the egg; it bears no relationship to the future plane of bilateral symmetry of the larva. The timing of regional specification was examined by isolating animal, vegetal, or meridional halves from oocytes, eggs, or embryos from prior to germinal vesicle breakdown through gastrulation. Animal halves isolated from oocytes formed either the epithelium of the apical lobe or a larva with all three germ layers. Animal halves isolated from unfertilized eggs and eight-cell embryos formed only apical lobe epithelium. Beginning at the blastula stage, animal halves formed mantle in addition to apical lobe epithelium. In animal halves isolated after gastrulation, the mantle lobe was always truncated. Vegetal halves isolated at all stages prior to gastrulation gastrulated and formed apical and mantle lobes with endoderm and mesoderm; however, the relative size of the apical lobe that formed decreased substantially when vegetal halves were isolated at later developmental stages. When meridional halves were isolated from unfertilized eggs and two- to four-cell embryos, both halves frequently formed normally proportioned larvae. Beginning at the blastula stage, a number of pairs frequently had a member that lacked dorsal setae on its mantle lobe while the other member of the pair formed setae, indicating that the dorsoventral axis had been set up. The process of regional specification in Crania is compared to those of Discinisca and Glottidia in the brachiopod subphylum Linguliformea and Phoronis in the phylum Phoronida.

Monophyly of brachiopods and phoronids: reconciliation of molecular evidence with Linnaean classification (the subphylum Phoroniformea nov.)

Molecular phylogenetic analyses of aligned 18S rDNA gene sequences from articulate and inarticulate brachiopods representing all major extant lineages, an enhanced set of phoronids and several unrelated protostome taxa, confirm previous indications that in such data, brachiopod and phoronids form a well-supported clade that (on previous evidence) is unambiguously affiliated with protostomes rather than deuterostomes. Within the brachiopod-phoronid clade, an association between phoronids and inarticulate brachiopods is moderately well supported, whilst a close relationship between phoronids and craniid inarticulates is weakly indicated. Brachiopod-phoronid monophyly is reconciled with the most recent Linnaean classification of brachiopods by abolition of the phylum Phoronida and rediagnosis of the phylum Brachiopoda to include tubiculous, shell-less forms. Recognition that brachiopods and phoronids are close genealogical allies of protostome phyla such as molluscs and annelids, but are much more distantly related to deuterostome phyla such as echinoderms and chordates, implies either (or both) that the morphology and ontogeny of blastopore, mesoderm and coelom formation have been widely misreported or misinterpreted, or that these characters have been subject to extensive homoplasy. This inference, if true, undermines virtually all morphology-based reconstructions of phylogeny made during the past century or more.

Regional Specification during Embryogenesis in the Inarticulate BrachiopodDiscinisca

The process of embryogenesis is described for the inarticulate brachiopodDiscinisca strigataof the family Discinidae. A fate map has been constructed for the early embryo. The animal half of the egg forms the dorsal ectoderm of the apical and mantle lobes. The vegetal half forms mesoderm and endoderm and is the site of gastrulation; it also forms the ectoderm of the ventral regions of the apical and mantle lobes of the larva. The plane of the first cleavage goes through the animal–vegetal axis of the egg along the future plane of bilateral symmetry of the larva. The timing of regional specification in these embryos was examined by isolating animal, vegetal, or lateral regions at different times from the 2-cell stage through gastrulation. Animal halves isolated at the 8-cell and blastula stages formed an epithelial vesicle and did not gastrulate. When these halves were isolated from blastulae they formed the cell types typical of apical and mantle lobes. Vegetal halves isolated at all stages gastrulated and formed a more or less normal larva; the only defect these larvae had was the lack of an apical tuft, which normally forms from cells at the animal pole of the embryo. When lateral isolates were created at all developmental stages, these halves gastrulated. Cuts which separated presumptive anterior and posterior regions generated isolates at the 4-cell and blastula stages that formed essentially normal larvae; however, at the midgastrula stage these halves formed primarily anterior or posterior structures indicating that regional specification had taken place along the anterior–posterior axis. The plane of the first cleavage, which predicts the plane of bilateral symmetry, can be shifted by either changing the cleavage pattern that generates the bilateral 16-cell blastomere configuration or by isolating embryo halves prior to, or during, the 16-cell stage. These results indicate that while the plane of the first cleavage predicts the axis of bilateral symmetry, the axis is not established until the fourth cleavage. The development ofDisciniscais compared to development in the inarticulate brachiopodGlottidiaof the family Lingulidae and toPhoronisin the phylum Phoronida.

Ciliary Feeding Assisted by Suction From the Muscular Oral Hood of Phoronid Larvae.

Phoronid larvae have an oral hood upstream from a postoral encircling array of ciliated tentacles. Cilia move water over the hood and between the tentacles, from anterior to posterior. When an algal cell or other particle in this current contacts a tentacle, the neighboring part of the hood lifts, and the particle is drawn toward the mouth. The correlation between movements of hood and particles indicates that the particle moves with water entering the enlarged space beneath the hood. Each lift of the hood is preceded by contact between a particle and a tentacle. A hood lift follows contact with a particle anywhere along the length of a tentacle, and clearance rates are thus proportional to the total length of tentacles deployed and the velocity of the current past the tentacles. After being detained at the ciliary bands of tentacles, particles are transported by the hood lift at speeds exceeding measured transport along the frontal ciliated surfaces of other larval forms. Faster transport may aid capture of faster prey. The larva's feeding mechanism is unique to the phylum Phoronida. Larvae of brachiopods, bryozoans, hemichordates, and echinoderms have similar ciliary bands producing feeding currents, but none are known to transport food toward the mouth by suction produced by muscle contractions.

Hydrodynamic study of the functional morphology of the benthic suspension feeder Phoronopsis viridis (Phoronida)

Ambient water currents were altered by the morphology of an active suspension feeder, Phoronopsis viridis Hilton (phylum Phoronida), to produce a flow around its ciliated crown of feeding tentacles (lophophore). To test the effects of specific morphological characteristics on patterns of water movement, the morphology of model phoronids was varied and the resultant paths of water movement were compared to those around living phoronids. Living individuals were collected from the intertidal sandflats at Bodega Bay, California/USA, in the springs of 1984 and 1985. Although P. viridis actively produce a feeding current, use of various models demonstrated that the gross pattern of flow around a living phoronid was created by the physical interaction of its morphology with ambient currents. The important aspects of that morphology were the presence of a wide, porous crown of tentacles atop a cylindrically-shaped body. A hydrodynamic consequence of this morphology was that dye eroded off the substratum from a circular area around the base of the body and entrained upwards into the lophophore. In addition, rates of water movement were slowed at the lophophore and near the substratum adjacent to a phoronid, particles were slowed and diverted from horizontal paths immediately downstream of the lophophore, and the number of visible suspended particles within the wake per unit time increased with ambient velocity. Paths of water movement around a phoronid were also influenced by its angle and height relative to the substratum, indicating that P. viridis could behaviorally modify their local flow environment.

A new genus of Lichomolgidae (Copepoda: Poecilostomatoida) associated with a phoronid in Hong Kong

A new genus of Lichomolgidae (Copepoda: Poecilostomatoida) associated with a phoronid in Hong Kong

Evaluation of bovine capacitation by [formula omitted] fertilization

The process of embryogenesis is described for the inarticulate brachiopodDiscinisca strigataof the family Discinidae. A fate map has been constructed for the early embryo. The animal half of the egg forms the dorsal ectoderm of the apical and mantle lobes. The vegetal half forms mesoderm and endoderm and is the site of gastrulation; it also forms the ectoderm of the ventral regions of the apical and mantle lobes of the larva. The plane of the first cleavage goes through the animal–vegetal axis of the egg along the future plane of bilateral symmetry of the larva. The timing of regional specification in these embryos was examined by isolating animal, vegetal, or lateral regions at different times from the 2-cell stage through gastrulation. Animal halves isolated at the 8-cell and blastula stages formed an epithelial vesicle and did not gastrulate. When these halves were isolated from blastulae they formed the cell types typical of apical and mantle lobes. Vegetal halves isolated at all stages gastrulated and formed a more or less normal larva; the only defect these larvae had was the lack of an apical tuft, which normally forms from cells at the animal pole of the embryo. When lateral isolates were created at all developmental stages, these halves gastrulated. Cuts which separated presumptive anterior and posterior regions generated isolates at the 4-cell and blastula stages that formed essentially normal larvae; however, at the midgastrula stage these halves formed primarily anterior or posterior structures indicating that regional specification had taken place along the anterior–posterior axis. The plane of the first cleavage, which predicts the plane of bilateral symmetry, can be shifted by either changing the cleavage pattern that generates the bilateral 16-cell blastomere configuration or by isolating embryo halves prior to, or during, the 16-cell stage. These results indicate that while the plane of the first cleavage predicts the axis of bilateral symmetry, the axis is not established until the fourth cleavage. The development ofDisciniscais compared to development in the inarticulate brachiopodGlottidiaof the family Lingulidae and toPhoronisin the phylum Phoronida.

Size and shape in the phylum Phoronida

The lophophorate phylum Phoronida consists of about 13 species, which differ in body length and width, number of longitudinal muscles, lophophore geometry and number of lophophore tentacles. In absolute terms large species have a larger body width, more tentacles, more longitudinal muscles and greater coiling of the lophophore than small species. However, size and shape analyses suggest that with increasing size: (I) the body surface area to volume ratio increases because body length increases faster than body width; (2) the relative number longitudinal muscles decreases, and (3) the relative feeding surface area of the lophophore decreases because tentacle diameter is constant while tentacle number increases at the same rate as body length and tentacle length increases more slowly than tentacle number. Coiling and spiraling of the lophophore in large species may be an attempt to compensate for this last relationship. We suggest that the habits, mode of growth and feeding mechanism of phoronids constrain size‐related changes in shape.

The hemoglobins of Phoronopsis viridis, of the primitive invertebrate phylum phoronida: Characterization and subunit structure

The primitive invertebrate, Phoronopsis viridis, of the phylum Phoronida, has intra-cellular hemoglobins composed of four unique polypeptide chains, two of which associate to form hetero- and homodimers and two which do not associate at all. The CO-derivatives of the associating chains are completely dimeric; removal of the ligand does not result in further aggregation as it does in several other invertebrate hemoglobins. Oxidation of the associating hemoglobins is accompanied by dissociation to monomers, but the cyanide derivative of the methemoglobin is dimeric. The four polypeptide chains all have molecular weights of about 16,000 as determined by iron content and gel electrophoresis with sodium dodecyl sulfate. The two associating chains form three components with isoelectric points at pH 5.6, 5.9, and 6.9 whereas those for the two monomeric chains are at pH 6.2 and 7.9. The chains have been characterized by amino acid composition, tryptic peptide patterns, and the amino acid sequence of the NH 2-terminal segment. The oxygen equilibrium of a dimeric fraction has been determined at pH 7.5 and 20 °C; the pressure of half-saturation is 2.3 mm Hg.

Terminology in Phoronida

AbstractA terminology (in three languages) of the main descriptive terms of the anatomy of the phylum Phoronida is established and proposed to facilitate communication in future anatomical studies and taxonomical works. A brief discussion is given of the names (Latin and common) of this phylum. The present note must be considered as a preliminary work on nomenclature problems.