Ventral Bar Research Articles

Elastic energy storage in the mantis shrimp's fast predatory strike

Storage of elastic energy is key to increasing the power output of many biological systems. Mantis shrimp (Stomatopoda) must store considerable elastic energy prior to their rapid raptorial strikes; however, little is known about the dynamics and location of elastic energy storage structures in this system. We used computed tomography (CT) to visualize the mineralization patterns in Gonodactylaceus falcatus and high speed videography of Odontodactylus scyllarus to observe the dynamics of spring loading. Using a materials testing apparatus, we measured the force and work required to contract the elastic structures in G. falcatus. There was a positive linear correlation between contraction force and contraction distance; alternative model tests further supported the use of a linear model. Therefore, we modeled the system as a Hookean spring. The force required to fully compress the spring was positively correlated with body mass and appendage size, but the spring constant did not scale with body size, suggesting a possible role of muscle constraints in the scaling of this system. One hypothesized elastic storage structure, the saddle, only contributed approximately 11% of the total measured force, thus suggesting that primary site of elastic energy storage is in the mineralized ventral bars found in the merus segment of the raptorial appendages. Furthermore, the intact system exhibited 81% resilience and severing the saddle resulted in a non-significant reduction to 77% resilience. The remarkable shapes and mineralization patterns that characterize the mantis shrimp's raptorial appendage further reveal a highly integrated mechanical power amplification system based on exoskeletal elastic energy storage.

Phenotypic plasticity of taxonomic and diagnostic structures in gyrodactylosis-causing flatworms (Monogenea, Platyhelminthes)

The present study addresses the effect of varying temperature and host species on the size and shape of the opisthaptoral hard-parts in isogenic strains of Gyrodactylus salaris and G. thymalli. Variation in shape was examined using geometric morphometrics. Since the opisthaptoral hard-parts of Gyrodactylus have few specific landmarks, their shape information mostly being represented by outlines and surfaces, a method based on sliding semi-landmarks was applied. The ventral bars of G. salaris did not follow the previously postulated negative correlation between size and temperature, and the largest hamuli and marginal hooks from G. salaris and the smallest from G. thymalli clearly overlapped in size. Consistent shape differences with temperature were detected for the hard-parts from G. thymalli but not from G. salaris. The hard-parts of G. salaris were similar in size but significantly different in shape when grown on secondary hosts rather than the primary host.

Morphological and Molecular Taxonomy of a New Species of Fundulotrema and Comments on Gyrodactylus stephanus (Monogenea: Gyrodactylidae) from Fundulus heteroclitus (Actinopterygii: Cyprinodontiformes) in Nova Scotia, Canada

Fundulotrema porterensis n. sp. (Monogenea: Gyrodactylidae) is described from the mummichog, Fundulus heteroclitus (L.; Cyprinodontidae), inhabiting Porters Lake, Nova Scotia, Canada. The new parasite species is characterized by having a ventral bar with small anterolateral processes and linguiform membrane, differentiating it from all other known species of Fundulotrema. The morphological description of F. porterensis is supplemented with 1011 sequenced base pairs (bp) of ribosomal DNA (rDNA) spanning both internal transcribed spacers (ITS-1 and ITS-2) and 5.8S regions of the genome. A BLAST (basic local alignment search tool) search revealed that the 5.8S (157 bp) region varied by 1 bp from Gyrodactylus turnbulli Harris, 1986 and G. pictae Cable, Oosterhout, Barson and Harris, 2005, which also infect cyprinodontids. Morphometrically, F. porterensis most closely resembles Fundulotremafoxi (Rawson, 1973), but the 2 species are easily separated by length of hamuli (50.7 vs. 42.2 microm, respectively), length of anterolateral process of the ventral bar (4.9 vs. 8.9 microm), shape of marginal hooks, and shape of the ventral bar membrane. A morphological and molecular supplemental diagnosis of Gyrodactylus stephanus Mueller, 1937, from the mummichog, is also presented. This new material provides previously unrecorded information on the attributes of the ventral bar, marginal hooks, and also clarifies the structure of the male copulatory organ (MCO).

Description of Gyrodactylus notatae n. sp. (Monogenea: Gyrodactylidae) from Menidia menidia (L.) (Actinopterygii: Atherinidae) in Nova Scotia, Canada

Gyrodactylus notatae n. sp. (Monogenea: Gyrodactylidae) is described from the fins and gills of the Atlantic silverside Menidia menidia (L.) (Atherinidae) inhabiting the brackish water of Lawrencetown Lake, Nova Scotia, Canada. G. notatae n. sp. is the first monogenean to be reported from M. menidia. It is characterised by having stout hamuli, a ventral bar with small anterolateral processes and a linguiform membrane, a cylindrical dorsal bar, a male copulatory organ (MCO) with a single large and only three small terminal spines, and a marginal hook sickle that is wider distally than proximally. The new species most closely resembles species of the G. wageneri-group, particularly G. pungitii Malmberg, 1964, but is distinguished by the smaller dimensions of all of its haptoral components. The morphological description of G. notatae is supplemented with 1,028 sequenced base pairs (bp) of ribosomal DNA (rDNA) spanning the ITS-1, 5.8S and ITS-2 regions, with which a BLAST (Basic Local Alignment Search Tool) search failed to provide close matches (c.80%). G. notatae is only the second species of viviparous monogenean to be described from species of Menidia, the other being G. nannus Rogers, 1968 from M. beryllina (Cope) in the southern USA. The two species appear to be from different lineages within Gyrodactylus von Nordmann, 1832.

A new species of Aphanoblastella (Monogenea: Dactylogyridae) parasitic on <em>Rhamdia quelen</em> (Siluriformes: Heptapteridae) from Southeastern Brazil

Aphanoblastella juizforense sp. nov. is described in the gills of the heptapterid fish Rhamdia quelen (Quoy et Gaimard, 1824) from the Paraibuna River, Juiz de Fora, Minas Gerais State, Brazil. The new species can be separated from all congeners by the long coiled copulatory organ with one counterclockwise ring; sinuous accessory piece and for the robust shape of the ventral bar.

A New Gyrodactylid (Monogenea) Genus on Gray Bichir, Polypterus senegalus (Polypteridae) from Senegal (West Africa)

Diplogyrodactylus martini n. g. et sp., a viviparous monogenean, is described from the gills of gray bichir Polypterus senegalus Cuvier, 1829, in Senegal. This new genus can be readily distinguished from the other described viviparous genera based on the morphology of the attachment apparatus. The haptor is equipped with a pair of centrally positioned hamuli, a simple ventral bar without membrane and 8 pairs of marginal hooks of 2 types, 5 pairs of hooks with well-defined large falculate sickles, and 3 pairs of smaller hooks with well-articulated sickles. The new genus is unique in having a teardrop-shaped muscular tubular male copulatory organ which lacks spines. A partial sequence of the internal transcribed spacer (ITS rDNA) was obtained from 4 specimens of D. martini. The relationship among D. martini and other genera of the Gyrodactylidae is discussed based on the similarities of the attachment apparatus.

Morphology and molecular taxonomy of Gyrodactylus jennyae n. sp. (Monogenea) from tadpoles of captive Rana catesbeiana Shaw (Anura), with a review of the species of Gyrodactylus Nordmann, 1832 parasitising amphibians

Gyrodactylus jennyae n. sp. is described from the body surface and mouthparts of tadpoles of the bullfrog Rana catesbeiana Shaw imported presumably from Missouri, USA, into a federal government facility in Moncton, New Brunswick, Canada. Its morphology resembles most closely that of G. chologastris Mizelle, Whittaker & McDougal, 1969 described from two amblyopsids (blind cave fishes) in Kentucky and North Carolina. Both species have long slender hamuli, a ventral bar with a relatively long membrane and small anterolateral processes, a cirrus with two rows of small spines and marginal hooks with a well-developed sickle heel and short handle. The two species differ morphologically; G. jennyae has a marginal hook sickle with a more pronounced heel than that found in G. chologastris. A BLAST search using a 945 base pair sequence that included the nuclear ribosomal DNA internal transcribed spacers 1 and 2 and the 5.8S rRNA gene from G. jennyae n. sp. showed that the overall similarity with other Gyrodactylus sequences on GenBank was relatively low. The ITS1 region was similar to that of G. misgurni Ling, 1962; however, no ITS2 and 5.8S rRNA sequences are available for that species. A separate search using 5.8S sequences revealed that G. markakulensis Gvosdev, 1950 and G. laevis Malmberg, 1957 were the closest to G. jennyae (1 and 2 bp differences, respectively). These species are parasites of cyprinids (or their predators) and are similar to G. jennyae and G. chologastris in having a double row of small hooks on the cirrus and overall similar morphologies of the haptoral hard parts. There are now five species of Gyrodactylus described exclusively from amphibians and this appears to have involved at least three separate host-switches from fishes.

Redescription of Ligophorus mediterraneus Sarabeev, Balbuena & Euzet, 2005 (Monogenea: Ancyrocephalidae) with some methodological notes

A redescription of Ligophorus mediterraneus Sarabeev, Balbuena & Euzet, 2005, based on original material from the Black and Mediterranean Seas, is presented and new diagnostic characters for its recognition are proposed. The unlikely wide range of variation in the angle between the shaft and point of the anchors, reported for this species and for some others in the genus, is analysed, and the structure of the ventral bar in Ligophorus spp. is described and its taxonomic significance discussed.

Two New Antarctic Gyrodactylus Species (Monogenoidea): Description and Phylogenetic Characterization

Two new species of Gyrodactylus Nordmann, 1832 (Gyrodactylidae, Monogenoidea) are described, i.e., Gyrodactylus coriicepsi n. sp. from gills of black rockcod, Notothenia coriiceps Richardson, 1844, and Gyrodactylus nudifronsi n. sp. from gills of gaudy notothen, Lepidonotothen nudifrons Lönnberg, 1905, collected in waters surrounding the South Shetland Islands, Antarctica. Gyrodactylus coriicepsi n. sp. is characterized by a long, narrowing membrane of the ventral bar and a marginal hook sickle with beveled heel and toe. Gyrodactylus nudifronsi n. sp. is characterized by a conspicuous ventral bar process and barely curved marginal hook sickle with curved heel and toe. Definitive species identification and phylogenetic position were based on sequences of the rDNA region (ITS1-5.8S-ITS2). Both new species belong to a monophyletic group (bootstrap support 99%) that includes the European marine species Gyrodactylus perlucidus Bykhovskiy and Polyanskiy, 1953 (on Zoarces viviparus), Gyrodactylus flesi Malmberg, 1957 and G. robustus Malmberg, 1957 (both on Platichthys flesus), and the freshwater species Gyrodactylus hrabei Ergens, 1957 and Gyrodactylus mariannae (both on Cottus poecilopus). The observations suggest an evolutionary continuum of the marine Gyrodactylus spp. fauna in the northern and southern hemispheres, which indicates the marine origin of some freshwater Gyrodactylus species.

Two New Species of Gyrodactylus von Nordmann, 1832 (Monogenea: Gyrodactylidae) Parasitizing Girardinichthys multiradiatus (Cyprinodontiformes: Goodeidae), an Endemic Freshwater Fish from Central Mexico

Gyrodactylus mexicanus n. sp. and Gyrodactylus lamothei n. sp. are described from the fins and skin of Girardinichthys multiradiatus, an endemic freshwater fish from central Mexico. Gyrodactylus mexicanus is compared to other Gyrodactylus species that parasitize Fundulus spp., the phylogenetically closest group to the Goodeidae from North America. Gyrodactylus mexicanus is distinguished by having large anchors with well-developed superficial roots, enlarged hooks with a proximally disrupted shank (ligament), and a ventral bar with 2 poorly developed anterolateral projections and a small medial process. Gyrodactylus lamothei is distinguished from G. mexicanus and from other species of Gyrodactylus on the North American continent by having anchors with a sclerite on the superficial root and robust hooks with a straight shaft and a recurved point.

Gyrodactylus orecchiae sp. n. (Monogenea: Gyrodactylidae) from farmed populations of gilthead seabream (Sparus aurata) in the Adriatic Sea

Gyrodactylus orecchiae sp. n. (Monogenea, Gyrodactylidae) is described from the skin, fins, eyes and gills of juvenile Sparus aurata L. (gilthead seabream) following two outbreaks of gyrodactylosis amongst stocks held in inshore floating cages on the Adriatic coast of Albania and Croatia. Fish were heavily infected (1000+ gyrodactylids/fish) with G. orecchiae which reportedly resulted in approximately 2-10% mortality amongst the infected stock. Morphologically, the haptoral hooks of G. orecchiae most closely resemble those of Gyrodactylus arcuatus Bychowsky, 1933 in the approximate shape of the ventral bar with its pronounced ventral bar processes and marginal hook sickles which possess a square line to the inner edge of the sickle blade and large rounded heels. The marginal hooks are also morphologically similar to those of Gyrodactylus quadratidigitus Longshaw, Pursglove et Shinn, 2003 and Gyrodactylus colemanensis Mizelle et Kritsky, 1967, but G. orecchiae can be readily discriminated from all three species by the characteristic infolding of the hamuli roots and the shape of the marginal hook sickle. Molecular sequencing of the ITS1, 5.8S, ITS2 regions (513+157+404 bp, respectively) of G. orecchiae and alignment with other gyrodactylids for which these same genomic regions have been determined, suggests that this is a new species. No similarities were found when the ITS1 region of G. orecchiae was compared with 84 species of Gyrodactylus available on GenBank.

Description de trois Monogènes nouveaux, parasites branchiaux deMormyrus rume(Teleostei : Mormyridae) en Côte d’Ivoire

The study of the gill parasites from elephant fish Mormyrus rume Valenciennes, 1846 (Teleostei: Mormyridae) from the Ayamé man-made Lake (Ivory Coast) revealed the presence of three new monogenean species of the genus Bouixella Euzet & Dossou, 1976, which can be mainly distinguished from all other species of the genus by the morphology and the size of the sclerotised parts of the haptor (dorsal and ventral anchor, dorsal and ventral bar) and by the size and the structure of the male copulatory organ. In this paper, descriptions of Bouixella gorei n. sp., Bouixella yaoi n. sp. and Bouvixella koutouani n. sp. are given.

Dactylogyrids (Monogenoidea) Parasitizing the Gills of Astyanax Spp. (Characidae) From Panama and Southeast Mexico, a New Species of Diaphorocleidus and a Proposal for Characithecium N. Gen

Diaphorocleidus orthodusus n. sp. and Diaphorocleidus kabatai (Molnar, Hanek and Fernando, 1974) Jogunoori, Kritsky, and Venkatanarasaiah, 2004 are detailed from Astyanax orthodus and Astyanax aeneus, respectively. Palombitrema heteroancistrium (Price and Bussing, 1968) is described from specimens collected from A. aeneus, and Urocleidoides strombicirrus (Price and Bussing, 1967) is reported for the first time from A. aeneus and Astyanax fasciatus in Panama. Characithecium costaricensis (Price and Bussing, 1967) n. comb. is detailed based on specimens from A. aeneus. Characithecium costaricensis is characterized by having overlapping gonads, a medioventral vaginal aperture, a copulatory complex consisting of single counterclockwise coil of the copulatory organ that is articulated to the accessory piece, and a haptor having 2 pairs of anchors, dorsal and ventral bars, and 14 hooks. Measurements of body size varied substantially among individual worms, both within and across different host species and locations. However, the morphological differences were insufficient to separate species of Characithecium. This result suggests limited parasite speciation across sympatric species of Astyanax in Mexico and Panama.

Ligophorus uruguayense sp. nov. (Monogenea, Ancyrocephalidae), a gill parasite from Mugil platanus (Mugiliformes, Mugilidae) in Uruguay

AbstractThe present study describes a new species, Ligophorus uruguayense, parasitizing the gills of Mugil platanus Günther, 1880 from the coast of Uruguay. It differs from all other species of the genus mainly in the shape of the ventral bar, the thick process at the distal end of the inner root of ventral anchors, the J-shaped penis accessory piece and the vaginal tube showing transverse annulations at its distal end, the host species, and geographical distribution. This is the first description of a species of Ligophorus from a mullet in the South Atlantic Ocean.

Two new species of Dactylogyridae (Monogenoidea) on rose spotted snapper, Lutjanus guttatus (Osteichthyes: Lutjanidae), from the coasts of Nayarit and Sinaloa, Mexico

Two new species, one each in Haliotrema and Euryhaliotrema, from the gills of the rose spotted snapper, Lutjanus guttatus, Steindachner, 1869, in Nayarit and Sinaloa, northwestern coast of Mexico, are described. Haliotrema guttati n. sp. is differentiated from its congeners H. longihamus and H. heteracantha by the presence of a delicate membranous envelope at the base of the copulatory organ, ventral and dorsal anchors with a prominent bulge on the inner face of the shaft, the base of the dorsal anchors simply fenestrated, ventral and dorsal bars having wide ends, and the ventral and dorsal bars W-shaped. Euryhaliotrema perezponcei n. sp. is characterized by a coiled male copulatory organ with three counterclockwise rings.

Three new species of Protogyrodactylus Johnston & Tiegs, 1922 (Monogenoidea: Dactylogyridae) from the gills of the longtail silverbiddy Gerres longirostris (Teleostei: Gerreidae) in the Red Sea

Twenty-one specimens of the longtailed silverbiddy Gerres longirostris (Gerreidae) were examined for dactylogyrid parasites from the Nabq Managed Resource Protected Area, Ras Mohammed National Park (Red Sea) near Sharm El-Sheikh, South Sinai, Egypt. The diagnosis of Protogyrodactylus Johnston & Tiegs, 1922 was amended, and three new species, P. federicae n. sp., P. zullinii n. sp. and P. alatus n. sp., were recovered and described; the prevalence of each species was 100%. P. federicae most closely resembled P. alienus Bychowsky & Nagibina, 1974, but differed from it by possessing two anteromedial projections on the ventral bar, a claw-like ventral anchor sclerite and spatulate dorsal bars. P. zullini was most similar to P. quadratus Johnston & Tiegs, 1922, from which it differed by having a distal hook on the superficial root of the dorsal anchor, an evenly curved ventral anchor shaft and point, and a flange on the bulbous base of the male copulatory organ. P. alatus was closest to P. youngi Bychowsky & Nagibina, 1974, from which it differed by having delicate anchors and two prominent anteromedial processes on the ventral bar.

A new species of Sciadicleithrum (Monogenea, Dactylogyridae) parasitic on Geophagus brasiliensis (Perciformes, Cichlidae) from Guandu River, Southeastern Brazil

AbstractSciadicleithrum guanduensis sp. nov. is described from the gills of the cichlid fish Geophagus brasiliensis (Quoy et Gaimard, 1824) from Guandu River, Seropédica, Rio de Janeiro, Brazil. The new species differs from all congeners by the accessory piece of the male copulatory organ, which comprises a small, delicate sheath with articulated appearance, and by the presence of a large unique umbelliform membrane on the ventral bar.

Description deLamellodiscus confususn. sp. (Monogenea: Diplectanidae), parasite deSarpa salpa(Teleostei : Sparidae)

Lamellodiscus confusus n. sp., a diplectanid gill parasite of Sarpa salpa Linnaeus, 1758 (Sparidae) from the coast of Algeria, is described. This monogenean has been previously reported in Sarpa salpa, by various authors, under the name L. ignoratus. L. confusus n. sp. is included (among other Lamellodiscus of Mediterranean sparids) in the "ignoratus" sub-group (Amine & Euzet, 2005). L. confusus n. sp. can be distinguished from L. ignoratus by the shape and size of the haptoral ventral bar and the male copulatory organ. For comparison, illustrations of the ventral bar and the male copulatory organ of all Mediterranean species of the "ignoratus" sub-group are provided. The question of the host specificity of L. ignoratus is discussed.

Morphometric comparison of three members of the Gyrodactylus nemachili-like species group (Monogenea: Gyrodactylidae) on Barbatula barbatula L. in the Czech Republic, with a reinstatement of G. papernai Ergens & Bychowsky, 1967

The Gyrodactylus nemachili-like species complex, parasitising stone loach Barbatula barbatula L. in the Czech Republic, was investigated based on the detailed morphometric analysis of its haptoral hard parts. The existence of two species, G. jiroveci Ergens & Bychowsky, 1967 and G. pseudonemachili Ergens & Bychowsky, 1967 was confirmed. A standard discriminant analysis of the morphometric data showed a clear separation between specimens of G. jiroveci and another species or variant. Based on the morphology of the haptoral hard parts, this third species was more similar to G. jiroveci than to G. pseudonemachili. The differences between G. jiroveci and the third species were mainly in the morphology of the marginal hook sickle, but included the total length of the marginal hook, the length of the hamulus point, the length of the marginal hook sickle, the width of the ventral bar, and the width of the dorsal bar. Based on comparison with the original material, the third species was identified as G. papernai Ergens & Bychowsky, 1967, which has recently been considered a synonym of G. jiroveci. These analyses provided sufficient evidence for the restoration of G. papernai as a valid taxon. Partial sequences of the internal transcribed spacer rRNA genes (ITS rDNA) verified the validity of all three Gyrodactylus species studied.

Pseudodiplectanum syrticum n. sp. (Monogenea: Diplectanidae), a parasite of Synapturichthys kleinii (Teleostei: Soleidae) from off Tunisia

Pseudodiplectanum syrticum n. sp. (Monogenea: Diplectanidae) is described from the gills of Synapturichthys kleinii (Risso) collected from the Gulf of Gabès in the Mediterranean Sea off Tunisia. The new species differs from the congeneric species by the morphology of the penis and vagina. It resembles the Mediterranean species P. kearni Vala, Lopez-Roman & Boudaoud, 1980 from Solea vulgaris Quensel and P. gibsoni Oliver, 1987 from Michrochirus variegatus (Donovan) in its tubular penis, but it differs from these two species by having a vagina with a long tube presenting two loops and a male copulatory organ ending in a curved point. It also differs in the morphology and size of the transverse bars of the haptor. In P. syrticum the ventral transverse bar and dorso-lateral bars are longer than those of P. gibsoni (114 vs 69.5-89 microm and 48 vs 33-44 microm, respectively).