Patrick D. Mathews

Morphological and ultrastructural aspects of Myxobolus niger n. sp. (Myxozoa) gill parasite of Corydoras melini (Siluriformes: Callichthyidae) from Brazilian Amazon

Myxobolus niger n. sp. (Myxozoa) is described in the connective tissue of the serosa layer of the gill arch of Corydoras melini (Callichthyidae) captured from the Negro River, Amazonas State, Brazil. The prevalence of the parasite was 20% and the range intensity was 1-2 cysts per fish. The plasmodia were white and spherical to ellipsoidal, measuring 175 μm in diameter and were surrounded by a well-defined capsule of host connective tissue, with distinct delicate and interlaced collagen fibers. The myxospores body was ellipsoidal in frontal view and biconvex in sutural view. Spore dimensions were 11.3 ± 0.4 μm in length, 6.8 ± 0.2 μm in width and 4.1 ± 0.2 μm in thickness. The valves were symmetrical and smooth. The two polar capsules were elongated as pyriform and equal in size, measure 5.0 ± 0.3 μm in length and 2.0 ± 0.1 μm in width. The polar capsule had six to seven polar filament turns. Some aberrant spores were round in shape and had three polar capsules. The sporoplasm was binucleated and contained moderated number of sporoplasmosomes. The development of the plasmodia was asynchronic, with mature and immature spores. The plasmodium had moderated pynocitic channels. There were no projections, no invaginations and no microvilli in the plasmodial wall. This study is the first description of Myxobolus species in the fish of the Callichthyidae family.

Morphology and molecular phylogeny of a new Myxidium species (Cnidaria: Myxosporea) infecting the farmed turtle Podocnemis expansa (Testudines: Podocnemididae) in the Brazilian Amazon

This study reports, for the first time, a myxosporan species of the genus Myxidium in a Neotropical turtle. Myxidium turturibus n. sp., was found in the gall bladder of Podocnemis expansa (Testudines: Podocnemididae) farmed in Brazilian Amazon. Numerous disporic pseudoplasmodia in different developmental stages, and mature spores were free in the bile. Mature myxospores were fusiform, slightly arcuate in valval view, measuring 13.6±0.4 (13.1-15.1) μm in length and 4.1±0.3 (3.4-4.6) μm in width. The two polar capsules were piriform, with 3.4±0.4 (2.5-4.0) μm in length and 2.4±0.4 (1.5-2.7) μm in width and had five to six polar filament turns. Phylogenetic analysis inferred by 18S rDNA shows the new species closely related with M. hardella and M. chelonarum, which are parasites of freshwater/terrestrials turtles from Oriental Region.

Dispersion of chitosan in liquid crystalline lamellar phase: Production of biofriendly hydrogel of nano cubic topology

Bicontinuous cubic phases were produced with introduction of chitosan in phospholipid/water hydrogel, providing composites of defined molecular organization. The ratio of lipid/water was constant and swelling of lipids bilayer is delimited by incorporation of polymer molecules into the structure. By means of synchrotron small angle X-ray scattering we identified topologies of coexisting cubic phases. The expected liquid crystalline Lα lamellar phase was suppressed by 0.2wt% chitosan leading to formation of diamond Pn3m and gyroid Ia3d cubic topology, with close lattice distances. An increment to 0.4wt% chitosan caused large increase in Pn3m lattice distance. However a higher 0.6wt% evolved this phase to a newly acquired primitive Im3m topology. The structuring process of the three-dimensional complex network is principally governed by demands of chitosan physical requirements over lipids bilayers interfacial curvature. The composite hydrogel of specific topologies presents reduced time release of gallic acid and may find application as new material for time-sustained delivery of bioactive compounds.

Morphology and small subunit rDNA-based phylogeny of a new Henneguya species, infecting the ornamental fish Corydoras leucomelas from the Peruvian Amazon

A new species of Myxosporea, Henneguya loreotoensis n. sp. is described parasitizing the gill filaments from 17 of 35 specimens (48.5%) of Corydoras leucomelas (Siluriformes: Callichthyidae) caught in the Nanay River, near village Ninarumi, in the Loreto state, Peru. Mature spores were ellipsoidal in shape from the frontal view, measuring 36.2±0.1μm (36.1-36.3) in total length, 14.3±0.1μm (14.2-14.4) in body length, 5.1±0.1μm (4.9-5.3) in width and 21.9±0.1μm (21.8-22.0) in the caudal process. The two polar capsules were symmetrical and elongated, measuring 5.1±0.1μm (4.9-5.3) in length and 2.4±0.2μm (2.1-2.7) in width, containing a polar filament with five coils arranged obliquely to the longitudinal axis. The sporoplasm was binucleate. Partial sequencing of the ssu-rDNA of H. loretoensis n. sp. resulted in a total of 1676 nucleotides, and this sequence did not match any of the myxozoan available in the GenBank. The phylogenetic analysis shows H. loretoensis n. sp. as a sister species of Henneguya paraensis, another amazonian myxozoan parasite of Cichla temensis (Perciformes: Cichlidae).

A new Myxidium species (Myxozoa: Myxosporea) infecting the gallbladder of the turtle Podocnemis unifilis (Testudines: Podocnemididae) from Peruvian Amazon

A new myxosporean species, Myxidium peruviensis n. sp., is described parasitizing the gall bladder of the yellow-spotted river turtle Podocnemis unifilis kept in captivity in an Amazonian Peruvian turtle rescue unit in the city of Iquitos, State of Loreto, Peru. The parasite was found in four of ten (40%) P. unifilis examined. The new species was characterized based on morphological and molecular phylogeny analyses. SSU rDNA sequence of the spores of M. peruviensis n. sp. resulted in 1876 nucleotides and this sequence did no match any of the Myxozoa available in the GenBank. Phylogenetic analysis identified the new species as a sister species of Myxidium turturibus, the unique Myxidium species described in a Neotropical turtle. Nevertheless, the SSU rDNA sequences of the new species and M. turturibus have only a 91.5% similarity. This is the first description and molecular study of a Myxozoa in a reptile from Peru. Considering the status of P. unifilis as vulnerable species, the infection by Myxidium parasites is emphasized as possible disease impeller, representing menace to the turtle conservation.

Infestation by Ergasilus coatiarus (Copepoda: Ergasilidae) in two Amazonian cichlids with new host record from Peru: An ectoparasites natural control approach

The occurrence of copepods ergasilid was investigated in two species of cichlids of economic importance for aquaculture in the Amazon region: Cichla monoculus and Chaetobranchus semifasciatus. The fish were collected from a semi-intensive fish farm, near the city of Nauta, Loreto State, Peru. Copepods were found in the gill filaments of 44 of 85 specimens (51.7%) of C. monoculus and in eight of 30 (26.6%) specimens of C. semifasciatus. The parasite was identified as Ergasilus coatiarus based on its morphological features. The occurrence did not vary significantly with host size (P≥0.05) in both species. This is the first report of E. coatiarus parasitizing C. semifasciatus in the Amazon basin and the first report in C. monoculus from Peru. The high occurrence of these copepods in the present study points out the need of improving the strategies of parasitic prevention and control in order to better prevent future disease outbreaks.

Morphology and surface ultrastructure of Dadaytrema oxycephala (Digenea: Cladorchiidae) with a new host record from Peruvian Amazon floodplain

In this study, a new host record for Dadaytrema oxycephala (Digenea: Cladorchiidae) is described from an important Amazonian ornamental fish. The parasite was identified based in the general morphology and surface ultrastructure of the young and mature trematodes using scanning electron microscopy. The digenetic trematodes were found in the intestine of 15 of 80 specimens (18.7%) of Brochis multiradiatus captured from two floodplain lakes of the Amazonas River, Department of Loreto, Peru and no clinical signs were observed in the parasitized organ. This is the first report of D. oxycephala parasitizing fish of the genus Brochis in the Amazon basin and the first to report this parasite infection in an ornamental fish from Peru. Given that international trade of ornamental fish is a major factor for transboundary spreading of fish parasites and taking account that Peru is the second largest exporter of the Amazonian countries, there is a fundamental need of constant monitoring for diagnosis and timely control of infections by digeneans in order to better prevent introduction in new environments, dissemination and future disease outbreaks.

Morphology and 18S rDNA sequencing of Henneguya peruviensis n. sp. (Cnidaria: Myxosporea), a parasite of the Amazonian ornamental fish Hyphessobrycon loretoensis from Peru: A myxosporean dispersal approach

Myxosporean are endoparasitic cnidarians of wide distribution and responsible for important economic losses in fisheries and aquaculture. A new myxosporean species, Henneguya peruviensis n. sp., is herein described as obtained from the gill filaments of Hyphessobrycon loretoensis caught in the Nanay River, Department of Loreto, Peru. The parasite was found in 37 of 45 (82.2%) examined H. loretoensis. The new species was characterized based on morphological features and 18S rDNA gene sequence data. The sequencing of the 18S rDNA gene from the spores of H. peruviensis n. sp. resulted in 1632 nucleotides and this sequence did not match any of the myxozoan available in the GenBank. Phylogenetic analysis showed that H. peruviensis n. sp. closed together with H. leporinicola. Nonetheless, the 18S rDNA sequences of H. peruviensis n. sp. and H. leporinicola have only 82% similarity. This is the first description and molecular study of a Myxozoa parasitizing fish of the genus Hyphessobrycon in the Amazon basin. Given the importance of the ornamental fish industry in translocation of aquatic organisms worldwide, the international movement of myxosporeans in infected fish is discussed in terms of disease outbreaks and the need for preventative action.