Host-Parasite Interaction and Phylogenetic of a New Cnidarian Myxosporean (Endocnidozoa: Myxobolidae) Infecting a Valuative Commercialized Ornamental Fish from Pantanal Wetland Biome, Brazil.

Myxozoans are a diverse group of parasitic cnidarians of wide distribution. A new species, Myxobolus matogrossoensis n. sp., is herein described infecting wild specimens of tetra mato-grosso Hyphessobrycon eques, caught in the Pantanal biome, the world's largest tropical wetland area. Cysts were found in 3 of the 30 examined fishes. Mature myxospores were ovoid in shape in frontal and measured 6.6 ± 0.4 µm (6.2-7.0 µm) in length and 3.5 ± 0.2 µm (3.3-3.7 µm) in width. The two polar capsules were elongated in shape, equal in size and occupying almost half of the myxospore body. They measured 3.3 ± 0.2 µm (3.1-3.5 µm) in length and 1.8 ± 0.1 µm (1.7-1.9 µm) in width. The polar tubules presented three to four turns. Phylogenetic analysis placed the new species within a clade containing myxobolid species from South American characiforms fish and appears as a close species of Myxobolus piraputangae and Myxobolus umidus. Nevertheless, the sequences of the new species and P. umidus and P. piraputangae have a large genetic divergence of 12 and 12.2% in their 18S rDNA gene, respectively. To the best of our knowledge, this is the first report of a Myxobolus species parasitizing the tetra fish mato-grosso, thus increasing our knowledge of cnidarian myxosporean diversity from South America.

Ultrastructure, surface topography, morphology and histological observations of a new parasitic cnidarian of the marbled swamp eel from the world's largest tropical wetland area, Pantanal, Brazil.

Myxosporeans are a diverse group of microscopic cnidarians of wide distribution that evolved into a parasitic lifestyle. A new myxosporean species, Myxobolus sp., is herein described infecting the mandible of wild specimens of Synbranchus marmoratus, caught in the world's largest tropical wetland area, Pantanal, Brazil. Light, scanning, transmission electron microscopy and histological observations unveiled detailed taxonomic information of the new myxosporean cnidarian. Ultrastructural analysis revealed a detailed description of plasmodia structures which can be used for comparison with plasmodia from other species of myxobolids. Both histological and ultrastructural observations evidenced a connective tissue capsule surrounding the plasmodia of Myxobolus sp. as a histopathological host reaction to the infection of this parasitic cnidarian. Histology showed that tissue tropism of the new myxosporean occurs in a well-defined part of the mandible, with development of plasmodia occurring in the epidermis layer. Mature myxospores from the valvular view featured an ovoid shape and had a short prolongation of the spore valves in the posterior end. Myxospores measured 22.7 ± 1.2 µm (21.5-23.9 µm) in length, 12.5 ± 0.4 µm (12.1-12.9 µm) in width and 11.3 ± 0.5 (10.8-11.8 µm) in thickness. Polar capsules were pyriform equally-sized and measuring 4.6 ± 0.3 µm (3.9-4.3 µm) in length and 2.9 ± 0.1 µm in width (2.8-3.0 µm). Finally, this study substantiates the still hidden myxosporean diversity from South America.

Morphological and molecular characterization of Ameloblastella pirarara sp. n. (Monogenoidea: Dactylogyridae) parasitizing the large Amazonian catfish Phractocephalus hemioliopterus.

In this study, integrative taxonomy is applied to describe a new dactylogyrid species, Ameloblastella pirarara sp. n. from the gills of Phractocephalus hemioliopterus, a commercially and ecologically important Amazonian catfish. Ameloblastella pirarara sp. n. can be distinguished from its congeners mainly by the morphology of the male copulatory organ (MCO), accessory piece, and anchors. The new species most resembles Ameloblastella unapi, from the Peruvian Amazon, but differs from it by the number of MCO rings, morphology of the vaginal canal and sclerotized structures of the haptor. Phylogenetic analyses based on sequences of the partial 28S rDNA (D1-D2 domains) gene placed the new species in a well-supported subclade of Ameloblastella spp. parasites of Neotropical siluriform fish, as a sister taxon to Ameloblastella unapioides. Thus, the new species described herein expands our knowledge of the diversity of monogenoid parasites from Amazonian freshwater fish.

Correction to: Rules as Basic Units of Sociocultural Selection.

[This corrects the article DOI: 10.1007/s40614-019-00201-6.].

Rules as Basic Units of Sociocultural Selection.

In the context of applying behavior-analytic principles to the study of the evolution of human societies, we propose that rules constitute the basic units of sociocultural selection. Such thesis is based on a critical analysis of the ideas concerning sociocultural selection proposed by Skinner and Baum. Its point of departure is a new functional concept of rule uttering, defined as a special type of verbal behavioral pattern, whose probability of occurrence depends upon their probability of altering the frequency of certain kind of behavior in the repertoire of a given individual or group of individuals. These relatively lasting changes in the behavior of recipients include the uttering of rules appropriate to specific types of problem situations, which increase the likelihood of responses that solve the problems faced by the social group. According to the proposed model, rule-uttering behavioral patterns include rule application, rule transmission and rule creation, which are functionally distinguished by the social consequences they produce. Patterns of rule uttering are selected by operant mechanisms, in the sense that those that do not increase the probability of solving problems tend to stop occurring. It is proposed that the occurrence probability of generalized social reinforcers, associated to different functionally specialized social systems (e.g., money in the economy, sanctions in the legal system), constitutes the main consequence responsible for rule-uttering selection.

An integrative taxonomic study of Pavanelliella spp. (Monogenoidea, Dactylogyridae) with the description of a new species from the nasal cavities of an Amazon pimelodid catfish.

The present study is an integrative taxonomic analysis of Pavanelliella spp. (Monogenoidea, Dactylogyridae), and describes a new species from the nasal cavities of the Amazonian pimelodid catfish Brachyplatystoma rousseauxii (Siluriformes Pimelodidae) from the Tapajós River (Amazon Basin, Pará state, Brazil). Pavanelliella jarii sp. n. is characterized by the presence of 3-4 rings in the male copulatory organ, the absence of rings around the vaginal atrium and by its sinuous vaginal canal, which sometimes forms 0.5-1 rings in the distal portion. The sequencing of the small subunit ribosomal DNA (ssrDNA) and internal transcribed spacer 1 (ITS-1) of three species of Pavanelliella, Vancleaveus cicinnus, and an undetermined dactylogyrid allowed the phylogenetic reconstruction of these dactylogyrids. The analysis indicated that P. jarii sp. n. is closely related to Pavanelliella takemotoi and Pavanelliella pavanellii, which formed a sister clade to ancylodiscoidines parasites of siluriform fish from the Oriental and Afrotropical regions. The analysis also corroborated the non-monophyly of Ancyrocephalinae, revealing that ancylodiscoidines arose between ancyrocephalines lineages, in a sister relationship to pseudodactylogyrines+marine ancyrocephalines+ancyrocephalines parasites of afrotropical perciforms+dactylogyrines. Cladistical analysis indicates that the haptoral anchor/bar complex has been lost several times in the evolutionary history of Dactylogyridae. The analysis also indicated that Dactylogyrus is polyphyletic, as Acolpenteron ureteroecetes and Dactylogyroides longicirrus arose between the three lineages formed by Dactylogyrus spp.

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.

An analytical calculation of the peak efficiency for cylindrical sources perpendicular to the detector axis in gamma-ray spectrometry.

An analytical expression for the so-called full-energy peak efficiency epsilon(E) for cylindrical source with perpendicular axis to an HPGe detector is derived, using point-source measurements. The formula covers different measuring distances, matrix compositions, densities and gamma-ray energies; the only assumption is that the radioactivity is homogeneously distributed within the source. The term for the photon self-attenuation is included in the calculation. Measurements were made using three different sized cylindrical sources of 241Am, 57Co, 137Cs, 54Mn, and 60Co with corresponding peaks of 59.5, 122, 662, 835, 1173, and 1332 keV, respectively, and one measurement of radioactive waste drum for 662, 1173, and 1332 keV.

Peak efficiency calibration for attenuation corrected cylindrical sources in gamma ray spectrometry by the use of a point source.

A theoretical method of determining the gamma-ray peak efficiency for a cylindrical source, based on a modified expression for point sources is derived. A term for the photon self-attenuation is included in the calculation. The method is valid for any source material as long as the source activity concentration is considered to be homogeneous. Results of this expression are checked against experimental data obtained with (241)Am, (57)Co, (137)Cs, and (60)Co sources.

Determination of the activity concentration of a 238 Pu solution by the defined solid angle method utilizing a novel dual diaphragm-detector assembly.

The activity concentration of a (238)Pu solution was measured by the determined solid angle method employing a novel dual diaphragm-detector assembly, which has been previously described. Due to the special requirements of the detector, a new type of source holder was developed, which consisted of sandwiching the radioisotope between two organic films called VYNS. It was experimentally demonstrated that the VYNS films do not absorb alpha particles, but reduce their energy by an average of 22 keV.A mean activity concentration for (238)Pu of 359.10+/-0.8 kBq/g was measured.

Theoretical estimates of the solid angle subtended by a dual diaphragm-detector assembly for alpha sources.

Knowledge of the solid angle subtended by a detector is essential for the determination of the activity of a radioactive source. This work investigates the influence of diaphragm and source diameter, and source to diaphragm distance, on the solid angle subtended by a dual opposed alpha diaphragm-detector assembly. Expressions published by Segre, Ruby, and others, and the Monte Carlo method are used. The analytical expressions consistently produced higher estimates than the Monte Carlo method for the solid angle.