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At least 73 records · Page 4Linked to original sources
PubMed2001

Two new species of Macrobothridium (Cestoda: Diphyllidea) from rhinobatid elasmobranchs in the Gulf of Gabès, Tunisia, with notes on the status of the genus.

As a result of an investigation of metazoan parasites of elasmobranch fishes in the Gulf of Gabès, Tunisia, we discovered 2 new species of diphyllidean cestodes. Macrobothridium euterpes n. sp. is described from the spiral intestine of Rhinobatos rhinobatos, and Macrobothridium syrtensis n. sp. from the spiral intestine of Rhinobatos cemiculus. Macrobothridium euterpes is distinguished from the only other species in the genus (Macrobothridium rhynchobati) by the number of rostellar hooks, size, genital pore position, vagina position, and ovary shape. Macrobothridium syrtensis is distinguished from M. rhynchobati by the hook morphology, testis number, and overall size, and from M. euterpes by the number of rostellar hooks, testis number, genital pore position, vagina position, and ovary shape. These are the first 2 species added to the genus since its establishment in 1989. A standardized formula for representing the number and arrangement of rostellar hooks in diphyllidean species is presented.

Animals↗
PubMed2004

Schistobrachia jordaanae n. sp. (Copepoda: Siphonostomatoida: Lernaeopodidae) from gill filaments of a diamond ray (Gymnura natalensis) captured in the Indian Ocean and a key to species of Schistobrachia, Dendrapta, and Brianella.

Schistobrachia jordaanae n. sp. (Copepoda: Siphonostomatoida: Lernaeopodidae) is described from adult female specimens collected from gill filaments of a diamond ray Gymnura natalensis (Gilchrist and Thompson, 1911) captured in the Indian Ocean off the South African coast. Schistobrachia jordaanae is best distinguished from its congeners by 2 unique characteristics: it possesses a necklike region between the origin of its maxillae and maxillipeds and the tips of its maxillae bifurcate repeatedly to form a rootlike anchor.

Animals↗
PubMed2006

A redescription of the fish leech Pterobdella amara (= Rhopalobdella japonica) (Hirudinida: Piscicolidae) based on specimens from the type locality in India and from Australia.

Pterobdella amara is redescribed from specimens from the type locality in India, and from the type host in Queensland, Australia. A neotype is designated from the type locality. The presence of conspicuous finlike bodies along the lateral margins of P. amara was greatly exaggerated in the original description. The trachelosome and anterior portion of the urosome are wide and flat, but there are no finlike bodies present. The urosome tapers abruptly posterior to the flattened portion, becomes cylindrical, and remains of constant width to the caudal sucker. The oral sucker is small and the caudal sucker is terminal. The body is smooth and lacks pigmentation, except for 1 pair of eyes on the oral sucker. Important internal characters are 2 pairs of mycetomes, 5 pairs of testisacs, confluent gonopores, extensive accessory gland cells on the male atrium and ejaculatory ducts, a spacious coelom consisting of dorsal and ventral sinuses with expansive connections between each at urosome ganglia, and interganglionic expansions of the dorsal sinus. Rhopalobdella japonica from stingrays in Japan is synonymized with P. amara and becomes a subjective junior synonym. This leech is a parasite in the oral cavity of the stingrays Pastinachus sephen and Himantura uarnak in India and Australia, and Dasyatis akajei in Japan.

Animals↗
PubMed1986

Urea tolerance of myofibrillar proteins of two elasmobranchs: Squalus acanthias and Raja tengu.

Some biochemical properties of actomyosin and myosin from elasmobranchs, Squalus acanthias and Raja tengu are compared with those of a freshwater (Cyprinus carpio) and a marine teleost (Seriola quinquiradiata). Whereas Ca2+-ATPase of teleost actomyosins are more stable in the absence of urea, the reverse is true for elasmobranchs up to 1.0 M urea. In contrast to that of teleosts, the Mg2+-ATPase of S. acanthias actomyosin shows an activation in the presence of urea, where as that of R. tengu persists. Below 1.0 M urea, there is low incorporation of DTNB into thiols of elasmobranch myosins, and losses in alpha-helicity are reversible up to 5.0 M urea. The results, thus, demonstrate that for a certain concentration of urea, elasmobranch myofibrillar proteins may exhibit a group specific tolerance to urea.

Actomyosin↗
PubMed1999

Pararhinebothroides hobergi n. gen. n. sp. (Eucestoda: Tetraphyllidea) in Urobatis tumbesensis (Chondrichthyes: Myliobatiformes) from coastal Ecuador.

A new species of tetraphyllidean eucestode inhabiting Urobatis tumbesensis from inshore waters of southeastern Ecuador shares 3 synapomorphies with Rhinebothroides spp.: apical bothridial suckers poorly differentiated from the marginal loculi, internal seminal vesicles, and insertion of the vas deferens dorsally closer to the poral than the aporal end of the cirrus sac. The new species differs from Rhinebothroides spp. by lacking medial bothridial septa and loculi and having symmetrical ovarian arms, and possesses an apparent autapomorphic trait by having the vas deferens tapering to a narrow tube before entering the cirrus sac, extending posteriorly to the posterior end of the cirrus sac where it expands into an external seminal vesicle running ventral to the cirrus sac anteriorly to anterior to the vagina. In Rhinebothroides spp., the vas deferens is expanded into an external seminal vesicle near the insertion into the cirrus sac As the sister group of Rhinebothroides, we propose a new genus to accommodate the new species. Phylogenetic evaluation of phyllobothriids recently assigned to Anthocephalum shows that they represent a paraphyletic assemblage of species of varying degrees of relatedness to Rhinebothroides spp. and the new species. Uncovering the relationships of the new species and the various species assigned to Anthocephalum permitted reevaluation of character transformations used in previous phylogenetic analysis of Rhinebothroides. Transformation series for 3 characters, previously based on functional outgroup comparisons, changed and a new character, length of cirrus sac, was added. The new phylogenetic analysis differs from the previous hypothesis only in placing R. scorzai as the sister species of R. circularisi + R. venezuelae + R. moralarai rather than of R. freitasi + R. glandularis + R. mclennanae. The occurrence of the sister species of Rhinebothroides in a Pacific Ocean stingray adds additional support to the hypothesis of Pacific origins of South American freshwater stingrays.

Animals↗
PubMed1992

Cestode parasites in Potamotrygon motoro (Natterer) (Chondrichthyes: Potamotrygonidae) from southwestern Brazil, including Rhinebothroides mclennanae n. sp. (Tetraphyllidea: Phyllobothriidae), and a revised host-parasite checklist for helminths inhabiting neotropical freshwater stingrays.

Specimens of 5 species of cestodes were collected in 6 specimens of the freshwater stingray species Potamotrygon motoro (Natterer), collected in the vicinity of Corumba, Mato Grosso do Sul, Brazil. Acanthobothrium regoi, Potamotrygonocestus orinocoensis, Rhinebothroides venezuelensis, and Rhinebothrium paratrygoni are reported from P. motoro and from southwestern Brazil for the first time. Rhinebothroides mclennanae n. sp. appears to be the sister species of Rhinebothroides glandularis, the only other member of the genus exhibiting darkly staining glandular cells lying free in the parenchyma surrounding the terminal genitalia. The new species resembles Rhinebothroides glandularis, Rhinebothroides freitasi, and Rhinebothroides scorzai by having poral ovarian arms that extend anteriorly beyond the posterior margin of the cirrus sac, coiled vaginae, and vitelline follicles not interrupted on the poral side in the vicinity of the genital pore. It differs from all 6 previously described members of the genus by possessing an average of 31 testes per proglottid, compared with an average of 45 for R. glandularis, 55 for R. freitasi and R. venezuelensis, 77 for Rhinebothroides circularisi and Rhinebothroides moralarai, and 80 for R. scorzai. An updated phylogenetic tree for Rhinebothroides is presented.

Animals↗
PubMed1995

Serendip deborahae n. gen. and n. sp. (Eucestoda: Tetraphyllidea: Serendipidae n. fam.) in Rhinoptera steindachneri Evermann and Jenkins, 1891 (Chondrichthyes: Myliobatiformes: Myliobatidae) from southeastern Ecuador.

Cestodes collected in spiral valves of Rhinoptera steindachneri from the southern coast of Ecuador represent an undescribed species of Tetraphyllidea. The new species has bothridia possessing septa but lacking apical suckers. It is diagnosably distinct from all other tetraphyllidean genera by possessing a scolex comprising 4 triangular bothridia that are fused together forming a platelike structure, each of which is subdivided by 2 simple and 1 bifurcating septa radiating from its base and ringed by marginal loculi; therefore, a new genus is proposed for it. By exhibiting some degree of bothridial fusion, testes arranged in 2 layers in the proglottis and postovarian testes, the new species appears to be a member of a clade containing Dioecotaenia, Duplicibothrium, and Glyphobothrium. The new species possesses vitelline fields that converge dorsally in each proglottis, except for the ovarian and terminal genitalia areas, a feature that has been reported previously only in Duplicibothrium and Glyphobothrium. Furthermore, Duplicibothrium and Glyphobothrium, like the new species, are markedly protandric. Therefore, we propose that Duplicibothrium, Glyphobothrium, and the new species comprise the sister group of the Dioecotaeniidae, and propose a new family name for the clade. Tritaphros is rejected as a possible sister group for the clade; suggested alternatives include some species of Caulobothrium, Rhodobothrium, or some members of the Phyllobothrium centrurum group.

Animals↗
PubMed1996

On the status of the genus Pinguicollum (Tetraphyllidea: Onchobothriidae) with a redescription of P. pinguicollum.

Material of the poorly known Pinguicollum pinguicollum from Raja spp. in California from the personal collections of Nathan Riser and Mike Moser was examined by light and scanning electron microscopy. The presence of unusual triloculated bothridia covered with a layer of tissue, but capable of protruding through an aperture in this tissue, was confirmed. The species is also unusual in its lack of a muscular pad and apical sucker on each bothridium and in its possession of bifid hooks in which the axial prongs are conspicuously shorter than the abaxial prongs. The scolex was interpreted to consist of a short bothridial region and an elongate cephalic peduncle containing 4 pairs of robust longitudinal muscle bundles. The segment morphology is described in detail and figured for the first time. The ovary is bilobed in cross section; the testes are arranged in multiple rows in cross section. The apex of the scolex was found to possess elongate, filiform microtriches. The distal surfaces of the protrusible regions of the bothridia were covered with short filiform microtriches in the anterior and both short filiform microtriches and spiniform microtriches on the posterior bothridial surfaces. The remainder of the scolex and cephalic peduncle were covered with densely packed, spiniform microtriches of varying sizes. Based on the unusual bothridia, robust cephalic peduncle, and lack of muscular pad and apical sucker on the bothridia, it is recommended that the genus be considered to be valid. As all attempts to locate the type material of the species failed, a neotype is designated to facilitate future study of the genus.

Animals↗
PubMed1988

Dense-cored vesicle-containing components of the terminal nerve of sharks and rays.

This paper describes electron microscopic observations of dense-cored vesicle-containing axons, cell bodies, and endings of the terminal nerve in several elasmobranchs. The vesicles are found in two apparent cell types, one with a polymorphic nucleus and another with an oval nucleus. The types may correspond to cells producing one each of two neuropeptides (LHRH and FMRF-amide) that have previously been localized in the nerve. Dense-cored vesicles are found in many unmyelinated fibers in both the terminal nerve proper and its major ganglia. Some of these form complicated structures with interdigitation and wrapping of membranes. Vesicle-containing fibers branch from the nerve, run along nearby blood vessels, and appear to end adjacent to endothelial cells which demonstrate vesicular activity. The observations suggest terminal nerve neurosecretion into the cerebral circulation. Synapses are found in and near the ganglia where they appear to be axodendritic, with multiple contacts in some cases.

Animals↗
PubMed1987

Two classes of spontaneous miniature excitatory junction potentials and one synaptic vesicle class are present in the ray electrocyte.

Cross sections (1-2 mm thick) of the ray (Raja) tail were secured to a dish and immersed in elasmobranch saline. Spontaneous miniature excitatory junction potentials (MEJPs) were recorded by advancing a 50 k omega, KCl filled electrode into the electric organ (20 microV peak-to-peak baseline noise). Data were filmed, and/or recorded on magnetic tape for computer analyses. Intracellularly recorded MEJP amplitude histograms showed a peak at 60 microV and had a right-hand skew with MEJPs up to 0.5 mV. The small peak amplitude and the skewed amplitude distribution of intracellularly recorded MEJPs result from the relatively low input resistance and the short space constant of the electrocyte coupled with the dispersed synapses on the electrocyte. At 23 degrees C the intracellularly recorded MEJP frequency ranged from 1-10 MEJPs/s. The MEJPs became larger and became focally recorded as the electrode was advanced against the intracellular surface of the innervated membrane of the electrocyte. Focal extracellular MEJPs (reversed polarity) were also recorded with the electrode positioned against the outside surface of the innervated side of the electrocyte. The frequency of focally recorded intracellular MEJPs was increased (up to 40/s) when the electrode was pushed against the membrane. Focal MEJP frequencies decreased to a few/min within 5-10 min but the mean amplitude of 3-5 mV remained constant. Decreases in amplitude and frequency in focally recorded intracellular MEJPs are attributed to changes in electrode pressure against the membrane. Amplitude histograms were constructed from focally recorded intracellular or extracellular MEJPs which showed the same time characteristics. The focal MEJP amplitude histograms have two distinct classes, each forming a bell-shaped distribution. It is concluded that both classes are generated at the electrode tip. The smaller class of MEJPs has a mean 1/10th that of the larger class and composes about 2% of the MEJPs. The small class is analogous to the sub-MEPP class found in the frog sartorius (Kriebel and Gross 1974) and mouse diaphragm (Kriebel et al. 1976, 1982). Distributions of synaptic vesicle diameters are slightly log normal (right hand skew) such that the mean diameter (57 nm) is slightly larger than the modal value (52 nm). Vesicles touching the membrane were of the same size and diameter distribution as the entire vesicle population. The profiles of the distributions are smooth and suggest only 1 class of synaptic vesicle based on diameter.

Action Potentials↗
PubMed1986

Lithium in marine elasmobranchs as a natural marker of rectal gland contribution in sodium balance.

Natural concentrations of lithium in blood plasma and urine of several species of elasmobranchs and teleosts from the Black Sea and in rectal gland fluid of the former were determined by mass-spectrometric isotope dilution techniques. Unlike the teleosts, the elasmobranchs showed a prominent shift of Li/Na ratio in blood plasma with respect to the surrounding water, the plasma Li/Na ratio being five times lower than that of sea-water. Li-Na selectivity was found to be high in the kidneys and negligible in the rectal gland. Differences in Li-Na selectivity between kidneys and rectal gland are used as a basis for the method of estimation of relative contributions of these excretory organs in sodium excretion. Permanent contributions of the kidneys and rectal gland in sodium excretion of the ray Dasyatis pastinaca were found to be nearly equal.

Animals↗
PubMed1979

Patterns of purine nucleotides in fish erythrocytes.

1. The purine nucleotides were determined in the whole blood of 9 fresh water teleosts and 2 marine selachians. 2. GTP and ATP accounted for 88-99% of the total erythrocytes purines. 3. The ATP/ADP ratio ranged from 11 to 60 in the erythrocytes of the fish examined. 4. GTP is widely distributed in fish erythrocytes but its level ranged from 1 to 33 nmol/mg Hb (0.4 to 9 mumol/ml erythrocyte). 5. Lepomis and Esox exhibited a GTP/ATP ratio as elevated as in Anguilla; moreover the concentration of GTP per mol of Hb (physiologically most indicative) is higher in Lepomis, Esox, Ictalurus and Silurus than in Anguilla.

Animals↗
PubMed2006

Orpotrin: a novel vasoconstrictor peptide from the venom of the Brazilian stingray Potamotrygon gr. orbignyi.

Characterization of the peptide content of venoms has a number of potential benefits for basic research, clinical diagnosis, development of new therapeutic agents, and production of antiserum. In order to analyze in detail the peptides and small proteins of crude samples, techniques such as chromatography and mass spectrometry have been employed. The present study describes the isolation, biochemical characterization, and sequence determination of a novel peptide, named Orpotrin from the venom of Potamotrygon gr. orbignyi. The natural peptide was shown to be effective in microcirculatory environment causing a strong vasoconstriction. The peptide was fully sequenced by de novo amino acid sequencing with mass spectrometry and identified as the novel peptide. Its amino acid sequence, HGGYKPTDK, aligns only with creatine kinase residues 97-105, but has no similarity to any bioactive peptide. Therefore, possible production of this peptide from creatine kinase by limited proteolysis is discussed. Taken together, the results indicate the usefulness of this single-step approach for low molecular mass compounds in complex samples such as venoms.

Amino Acid Sequence↗
PubMed2000

New species of the Monocotylidae (Monogenea) from the stingray Dasyatis tortonesi Capapé (Euselachii, Dasyatidae) off the Tunisian coast, with comments on host-specificity and the specific identities of Mediterranean stingrays.

Heterocotyle capapei n. sp. and Thaumatocotyle tunisiensis n. sp. are described from the gills and the nasal cavity, respectively, of Dasyatis tortonesi collected from the Tunisian coast. H. capapei is distinguished from other species in the genus by the morphology of the penis, which is conical and has a long narrow distal point. T. tunisiensis differs from all known species of Thaumatocotyle by the shape and size of the penis. The host Dasyatis tortonesi has long been confused with D. pastinaca. Our study shows that their monogeneans are oioxenic, suggesting that D. pastinaca and D. tortonesi are distinct species. These results suggest that the monogenean parasite fauna could be used as a diagnostic tool for species identification: these parasites may, therefore, represent good biological indicators. The host-specificity of the Heterocotylinae and Merizocotylinae is discussed.

Animals↗
PubMed2000

Prochristianella spinulifera n. sp. (Cestoda: Trypanorhyncha) from Australian dasyatid and rhinobatid rays.

Prochristianella spinulifera n. sp. (Cestoda: Trypanorhyncha: Eutetrarhynchidae) is described from the spiral valves of the rays Rhinobatos typus (Rhinobatidae) and Himantura fai (Dasyatidae) from Heron Island, Queensland, Australia. The new species is distinguished from all congeners by the deltoid microtriches covering the anterior 80% of the scolex and the presence of a dorsoventrally elongate genital atrium. The species occurred in the anteriormost section of the spiral valve of R. typus. The orientation of the armature of this and other congeners is such that principal rows of hooks begin on the bothridial surface of the tentacle and end on the antibothridial surface.

Animals↗