Article

Phylogenetic relationships amongst Chloromyxum Mingazzini, 1890 (Myxozoa: Myxosporea), and the description of six novel species from Australian elasmobranchs

School of Biological Sciences, The University of Queensland, St Lucia, Queensland 4072, Australia.
Parasitology International (Impact Factor: 1.86). 11/2011; 61(2):267-74. DOI: 10.1016/j.parint.2011.10.008
Source: PubMed

ABSTRACT

Six novel species of Chloromyxum Mingazzini, 1890 are described using a whole evidence approach combining morphometric and molecular data, together with features of their biology. Elasmobranchs were collected in Australian waters, from the Great Barrier Reef, Queensland, off Lizard and Heron Islands; from Moreton Bay, southeast Queensland; off Hobart, Tasmania; and from the Tamar River, Launceston, Tasmania. The novel species proposed here are: Chloromyxum hemiscyllii n.sp. from Hemiscyllium ocellatum; Chloromyxum kuhlii n.sp. from Neotrygon kuhlii; Chloromyxum lesteri n.sp. from Cephaloscyllium laticeps; Chloromyxum mingazzinii n.sp. from Pristiophorus nudipinnis; Chloromyxum myliobati n.sp. from Myliobatis australis; and Chloromyxum squali n.sp. from Squalus acanthias. A seventh species from Squalus acanthias is also reported but due to limited material is not formally described. Molecular phylogenetic analyses revealed that the genus Chloromyxum is polyphyletic, and species from elasmobranchs form a well-supported sister clade, with the type species Chloromyxum leydigi, to all other congeneric species clustering within the freshwater myxosporean clade. Morphological analysis showed that elasmobranch-infecting species are predominantly pyriform shaped, have clearly thickened spore apex and possess caudal filaments, compared to other Chloromyxum species which are generally spherical or subspherical, and lack caudal filaments. These morphological and phylogenetic data provide further support for the erection of new genera, but we conservatively consider the species described in this study and other elasmobranch-infecting Chloromyxum species as Chloromyxum sensu strictu, whilst the freshwater teleost infecting and amphibian infecting species we will assign as Chloromyxum sensu lato, until more comprehensive data are available.

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    • "from elasmobranchs form a basal clade in the freshwater lineage (Fiala and Bartošová, 2010) assigned as the marine Chloromyxum clade (Jirků et al., 2011) or as the Chloromyxum s.s. clade (Gleeson and Adlard, 2012). Species of the genus Ceratomyxa from elasmobranchs represent one of the basal subgroups within the Ceratomyxa clade (unpublished data). "
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    ABSTRACT: Myxosporea (Myxozoa), a group of parasitic Cnidaria, use mostly bony fishes (Teleostei) as intermediate hosts; however, they can also parasitize other vertebrates such as cartilaginous fish (Chondrichthyes). Molecular data of myxosporeans from sharks and rays (Elasmobranchii) revealed these parasites to be one of the most basal representatives in the myxosporean phylogenetic tree, suggesting their ancient evolutionary history. A new myxosporean species, Bipteria vetusta n. sp., was found in the gall bladder of rabbit fish, Chimaera monstrosa (Holocephali; Chondrichthyes), and ssrDNA-based phylogeny revealed its basal position within the marine myxosporean lineage. Molecular dating based on ssrDNA analysis suggested the origin of a stem lineage leading to the marine myxosporean lineage at the time of the origin of Chondrichthyes in the Silurian era. The two common lineages of Myxozoa, Myxosporea and Malacosporea, were estimated to have split from their common ancestor in the Cambrian era. Tracing the history of evolution of the "vertebrate host type" character in the context of molecular dating showed that cartilaginous fish represented an ancestral state for all myxosporeans. Teleosts were very likely subsequently parasitized by myxozoans four times, independently. Myxosporean radiation and diversification appear to correlate with intermediate host evolution. The first intermediate hosts of myxosporeans were cartilaginous fish. When bony fish evolved and radiated, myxosporeans switched and adapted to bony fish, and subsequently greatly diversified in this new host niche. We believe that the present study is the first attempt at molecular dating of myxozoan evolution based on an old myxosporean species - a living myxosporean fossil. Copyright © 2015. Published by Elsevier Ltd.
    Full-text · Article · Feb 2015 · International Journal for Parasitology
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    • "Other studies, such as those of Eszterbauer [36], Milanin et al. [30], Gleeson and Adlard [37], Hartigan et al. [5] and Adriano et al. [28], have investigated the phylogenetic relationships of the species within a particular genus. These studies have demonstrated that many factors influence species clustering, such as the phylogenetic proximity of the host, tissue tropism, geographic distribution and morphology characteristics. "
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    ABSTRACT: The present study consists of a detailed phylogenetic analysis of myxosporeans of the Myxobolus and Henneguya genera, including sequences from 12 Myxobolus/Henneguya species, parasites of South American pimelodids, bryconids and characids. Maximum likelihood and maximum parsimony analyses, based on 18 S rDNA gene sequences, showed that the strongest evolutionary signal is the phylogenetic affinity of the fish hosts, with clustering mainly occurring according to the order and/or family of the host. Of the 12 South American species studied here, six are newly described infecting fish from the Brazilian Pantanal wetland. Henneguya maculosus n. sp. and Myxobolus flavus n. sp. were found infecting both Pseudoplatystoma corruscans and Pseudoplatystoma reticulatum; Myxobolus aureus n. sp. and Myxobolus pantanalis n. sp. were observed parasitizing Salminus brasiliensis and Myxobolus umidus n. sp. and Myxobolus piraputangae n. sp. were detected infecting Brycon hilarii.
    Preview · Article · Sep 2013 · PLoS ONE
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    • "In our analyses it forms a moderately supported group with other species of Chloromyxum that infect the gall bladders of freshwater fishes (Figure 7). However, in other analyses that are more focused on the phylogenetic relationships amongst Chloromyxum spp., its position is unresolved and it forms a solitary branch between a clade of urinary bladder infecting species and the Myxidium lieberkuehni clade, both of which contain Chloromyxum taxa [37]. It is likely that, when more molecular data exist for myxosporean taxa from the renal systems of amphibians, they will form a clade with C. careni reinforcing the potential importance of the Chloromyxum morphotype as ancestral forms to some of the currently recognised clades in myxosporean systematics. "
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    ABSTRACT: Background Approximately 40 species of Sphaeromyxa have been described, all of which are coelozoic parasites from gall bladders of marine fish. They are unique amongst the myxosporeans as they have polar filaments that are flat and folded instead of being tubular and spirally wound. This unusual feature was used as a subordinal character to erect the suborder Sphaeromyxina, which contains one family, the Sphaeromyxidae, and a single genus Sphaeromyxa. Methods In the present study, we examine eelpout from the genus Lycodes from Iceland for the presence of myxosporean parasites in the gall bladder and perform morphological and DNA studies. Results A novel myxosporean, Sphaeromyxa lycodi n. sp., was identified in the gall bladders of five of the six species of Lycodes examined, with a prevalence ranging from 29 - 100%. The coelozoic plasmodia are large, polysporous and contain disporic pansporoblasts and mature spores which are arcuate. The pyriform polar capsules encase long and irregularly folded ribbon-like polar filaments. Each spore valve has two distinct ends and an almost 180° twist along the relatively indistinct suture line. The single sporoplasm is granular with two nuclei. Sphaeromyxa lycodi is phylogenetically related to other arcuate sphaeromyxids and is reproducibly placed with all known sphaeromyxids and forms part of a robustly supported clade of numerous myxosporean genera which infect the hepatic biliary systems of a wide range of hosts. Conclusions Sphaeromyxa lycodi is a common gall bladder myxosporean in eelpout of the genus Lycodes from Northern Iceland. It has characteristics typical of the genus and develops arcuate spores. Molecular phylogenetic analyses confirm that sphaeromyxids form a monophyletic group, subdivided into straight and arcuate spore forms, within the hepatic biliary clade that infect a wide range of freshwater associated animals. The ancestral spore form for the hepatic biliary clade was probably a Chloromyxum morphotype; however, sphaeromyxids have more recently evolved from an ancestor with a spindle-shaped Myxidium spore form. We recommend that the suborder Sphaeromyxina is suppressed; however, we retain the family Sphaeromyxidae and place it in the suborder Variisporina.
    Full-text · Article · Mar 2013 · Parasites & Vectors
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