Abstract
BackgroundMyxozoans are metazoan parasites whose traditional spore morphology-based taxonomy conflicts DNA based phylogenies. Freshwater species of the genus Hoferellus are parasites of the excretory system, with several members infecting food and ornamental fish species, as well as amphibians. This study aims to increase our understanding of their molecular diversity and development, aspects about which little is known, and to generate a molecular diagnostic tool to discriminate between different pathogenic and non-pathogenic Hoferellus spp.MethodsSSU and ITS rDNA phylogeny, along with morphological descriptions using light and electron microscopy were used to identify and characterize Hoferellus species collected from the urinary system of fishes and frogs. A PCR-based diagnostic assay was designed to differentiate between cryptic Hoferellus spp in cyprinid fishes commonly cultured in Central Europe.ResultsOur phylogenetic results separate the species of Hoferellus into two phylogenetic sublineages which are indistinguishable on the basis of generic morphological traits: 1) The Hoferellus sensu stricto sublineage, which is composed of the type species Hoferellus cyprini, Hoferellus carassii and a cryptic species, Hoferellus sp. detected only molecularly in common carp. 2) The Hoferellus sensu lato sublineage into which the new species we described in this study, Hoferellus gnathonemi sp. n. from the kidney of the elephantnose fish and Hoferellus anurae from reed frogs, are placed together with Hoferellus gilsoni previously sequenced from European eel. Apart from phylogenetic analyses, we also provide novel ultrastructural data on the phagocytotic nature of some Hoferellus plasmodia and on the elusive intracellular stages ascribed to the presporogonic development of this genus.ConclusionsWe provide molecular evidence of the polyphyly of the genus Hoferellus and provide novel morphological details of its members. Based on the presented data, we revise and propose emendation of the genus Hoferellus.
Highlights
Myxozoans are metazoan parasites whose traditional spore morphology-based taxonomy conflicts DNA based phylogenies
Host sampling sites and collection methods Cyprinid fish were obtained from eight different localities, ponds and farms in the region of South Bohemia, Czech Republic, between February and November 2011-2013 (Table 1): Common carp C. carpio (n = 131; total length 2-50 cm, weight 1–2500 g), goldfish C. auratus (n = 114; total length 2–20 cm, weight 0.6–150 g) and Prussian carp C. gibelio (Bloch, 1782) (n = 12; total length 10.2–22.5 cm, weight 6–210 g)
Prevalence of Hoferellus spp Plasmodia of Hoferellus spp. in the lumina of the kidney tubules were observed with a prevalence of 13.2 % (15/ 114) in C. auratus from two localities and 13.8 % (18/ 131) in C. carpio from five localities, but were not observed in kidney tubules of C. gibelio (0/12)
Summary
Myxozoans are metazoan parasites whose traditional spore morphology-based taxonomy conflicts DNA based phylogenies. Freshwater species of the genus Hoferellus are parasites of the excretory system, with several members infecting food and ornamental fish species, as well as amphibians. Myxozoans are microscopic cnidarian parasites in aquatic environments and are known for the diseases they provoke in fisheries and aquaculture. They have complex life cycles alternating between intermediate vertebrate host, usually fish and other vertebrates, and a definitive. The type species, Hoferellus cyprini (Doflein, 1898) affects the renal system of common carp Cyprinus carpio L., one of the most cultured freshwater fish worldwide [14]. Most other species are known solely based on morphological description of spores, and only scarce molecular information is available for the members of this genus (2 partial SSU rDNA sequences)
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