Myxobolus miyairii Kudo, 1919 was first reported from the intestines of the Amur catfish (Silurus asotus) in Japan and then in China and Russia, but with incomplete description. During the investigation of fish myxosporean diversity in Poyang Lake, the biggest lake along the Yangtze River, China, two Amur catfish highly infected with M. miyairii in the intestine wall were sampled. So, the complete description of this species with morphological and molecular data was presented here. A large number of whitish, round or ellipsoidal pseudocysts 0.32-0.78 mm in diameter could be found in the external intestinal wall after dissecting the infected fish. Mature spores of M. miyairii were elongated and ellipsoidal in the frontal view and narrow fusiform in the lateral view, with a slightly pointed anterior end and a bluntly rounded posterior end and measured 13.3 ± 0.49 (12.5-14.7) μm × 6.6 ± 0.27 (6.2-7.4) μm × 5.0 ± 0.26 (4.4-5.7) μm in size. Spore surface was smooth and two spore valves symmetrical, with a thin and straight sutural ridge. Interestingly, two types of caudal appendage (single or bifurcated) were occasionally present on the posterior end of some spores which has not previously been reported. The two equal pyriform polar capsules measured 6.5 ± 0.30 (6.2-7.5) μm long and 1.9 ± 0.14 (1.5-2.3) μm wide and situated at the anterior end of the spore. Polar filaments coiled with eight to nine turns, perpendicularly to the longitudinal axis of the polar capsules. Histopathological analysis showed that the plasmodium developed in the circular muscle layer of intestinal wall of Amur catfish, but no obvious inflammatory responses were observed. Phylogenetic analysis based on the partial 18S small subunit ribosomal DNA sequences indicates that M. miyairii cluster within a clade of Siluriforme-infecting Henneguya species with the support of a high bootstrap value, but also evolutionarily independent from the Henneguya clade infecting the epithelium of fish of the Ictaluridae family. Additionally, Myxobolus species reported with caudal processes dispersed within the Henneguya-Myxobolus clade.
Crassulaceae is a mid‐sized family of angiosperms, most species of which are herbaceous succulents, usually with 5‐merous flowers and one or two whorls of stamens. Although previous phylogenetic studies revealed seven major “clades” in Crassulaceae and greatly improved our understanding of the evolutionary history of the family, relationships among major clades are still contentious. In addition, the biogeographic origin and evolution of important morphological characters delimiting infrafamilial taxa have not been subject to formal biogeographic and character evolution analyses based on a well‐supported phylogeny backbone. In this study, we used plastomic data of 52 species, representing all major clades revealed in previous studies to reconstruct a robust phylogeny of Crassulaceae, based on which we unraveled the spatiotemporal framework of diversification of the family. We found that the family may originate in southern Africa and then dispersed to the Mediterranean, from there to eastern Asia, Macaronesia, and North America. The crown age of Crassulaceae was dated at ca. 63.93 million years ago, shortly after the Cretaceous–Paleogene (K‐Pg) boundary. We also traced the evolution of six important morphological characters previously used to delimit infrafamilial taxa and demonstrated widespread parallel and convergent evolution of both vegetative (life form and phyllotaxis) and floral characters (number of stamen whorls, petals free or fused, and flower merism). Our results provide a robust backbone phylogeny as a foundation for further investigations, and also some important new insights into biogeography and evolution of the family Crassulaceae.
Extensive sampling to get rich data is very important to resolve the current taxonomic problem of Chloromyxum genus and elucidate the nature phylogenetic relationships among congeneric species. During the parasitological survey of cyprinid fish in Gulf of Finland off the coast of St. Petersburg, a new Chloromyxum species, named as Chloromyxum peleci sp. n., was found to infect the gall bladder of sichel, Pelecus cultratus (L.). Here, we provided the morphological, ultrastructural, and molecular features to describe it. Infection was represented by mono- or disporic plasmodia and mature free-floating spores in the gall bladder. Mature spores are typical of freshwater Chloromyxum species, spherical or subspherical in lateral view, measuring 8.8 ± 0.5 μm (7.4-9.5) in length, 7.8 ± 0.3 μm (7.0-8.8) in width, and 7.5 ± 0.4 μm (6.8-8.2) in thickness. Spores have a cog-like appearance in apical view for sutural ridge, and eight to ten widely spaced extrasutural ridges per valve protrude from the spore valve margin. The surface ridge patterns of the new species are similar with those of Chloromyxum auratum and Chloromyxum cristatum, with some branching. Four polar capsules of slightly unequal in two pairs were oval in apical view and pyriform in side view, locating at the anterior end of the spores. Polar filaments coil with four to five turns. The obtained almost full length of 18S ribosomal DNA (rDNA) of Ch. peleci sp. n. does not match any sequences available in GenBank but was most closely related to that of Chloromyxum fluviatile (97.9%). Phylogenetic analysis indicated that Ch. peleci sp. n. clustered in a Chloromyxum subclade infecting the gall bladder of freshwater teleost, with robust nodal support. However, Chloromyxum sensu lato infecting gall bladder of freshwater teleost was again proved to be polyphyletic. The possible evolutionary history of Chloromyxum morphotype of Chloromyxum sensu lato was discussed based on the rDNA-referred phylogeny. This is the second Chloromyxum species from sichel.
The traditional taxonomy of the genus Chloromyxum Mingazzini, 1890 has been intensively challenged to be paraphyletic by recent ribosomal DNA (rDNA)-based phylogenetic analysis. Undersampling to get rich sequence data to infer more scientific phylogenetic relationships makes scientists conservatively assign all non-marine elasmobranch-infecting species as Chloromyxum sensu lato. Although complex ridge pattern on the spore surface observed by scanning electron microscopy was thought to be critical for the identification of Chloromyxum species, insufficient data also prevent this ultrastructural data to be a valid taxonomic feature for this genus. It is especial for Chloromyxum species to be reported in China. Molecular and ultrastructural characteristics are yet available for all 22 Chloromyxum species recorded in China. During the investigation of the diversity of coelozoic fish myxosporeans, Chloromyxum ellipticum Li & Nie, 1973 was found to highly infect the gall bladder of Ctenopharyngodon idellus Valenciennes, 1844 in Poyang Lake watershed of Jiangxi province, Eastern China. Here, we redescribed it by the currently recommended holistic approach of combining morphological, ultrastructural, and molecular characteristics. Mature spores were found floating free in the gall bladder, but no plasmodium observed. Spores are typical freshwater teleost-infecting Chloromyxum species, spherical or subspherical in lateral view, measuring 7.7 ± 0.08 μm (6.9-9.1) in length, 6.3 ± 0.09 μm (5.6-7.6) in width, and 5.8 ± 0.20 μm (5.2-6.3) in thickness. Four pyriform polar capsules, located at the anterior end of the spores, were equal in size, 3.3 ± 0.06 μm (2.2-4.1) long and 2.1 ± 0.03 μm (1.7-2.5) wide. Polar filaments coiled with four to five turns. Two equal spore valves are symmetrical, with 10-16 surface extrasutural ridges per valve, aligned along the longitudinal axis. The obtained partial 18S rDNA of C. ellipticum did not match any sequences available in GenBank. Phylogenetic analysis showed that C. ellipticum clustered firstly with Chloromyxum legeri with robust nodal support and grouped then with urinary system of freshwater teleost-infecting Chloromyxum clade, rather than other gall bladder of freshwater teleost-infecting clade.
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