A New Myxozoan From Feral Goldfish (Carassius Auratus)

Abstract

In February 2004, a mass die-off of common goldfish Carassius auratus L., presumptively caused by bacterial coldwater disease (Flavobacterium psychrophilum), occurred at Fern Ridge Reservoir, Oregon. A range of size classes was affected, but all mature fish were female and all fish were infected with a single myxozoan, Chloromyxum auratum n. sp. No histological changes were observed associated with the parasite. Infection was represented by mictosporic plasmodia and free-floating spores in the gall bladder. Parasite spores were nearly spherical, 13.6 microm long x 12.6 microm wide x 13.1 microm thick, and possessed 4 equal-sized polar capsules. Spores had a coglike appearance in apical view because of distinct ridges 2.1 microm high protruding from the valve cells. There were 6-9 extrasutural ridges per valve (15-20 ridges per spore), aligned along the longitudinal axis, with some branching, and convergence at both poles. Morphologically, spores identified most closely with Chloromyxum cristatum Léger, 1906; however, 18S rDNA sequence data indicated only 97.5% similarity over 2,076 bp with Chloromyxum cyprini, the only synonym of C. cristatum for which DNA data are available; additional sequence data may reveal the other synonyms to be distinct species. This is the first record of a species of Chloromyxum from goldfish.

Ultrastructural and phylogenetic data of Chloromyxum riorajum sp. nov. (Myxozoa), a parasite of the stingray Rioraja agassizii in Southern Brazil

“…ellipsoidal spores with 2 shell valves, 4 equal-sized polar capsules and a bundle of caudal filamentous projections, shows the characters of a parasite belonging to the genus Chloromyxum (Lom & Noble 1984, Lom & Dyková 2006. A comparison of our results with the morphology and ultrastructural organization of previously described species of this genus, shows that the morphology is similar, which consequently confirms that this parasite belongs to this genus (Lom & Noble 1984, Lom et al 1988, Baska 1990, 1993, Molnár 1992, Shul'man & Ieshko 2003, Hallett et al 2006, Lom & Dyková 1992, 2006, although few of the previously described species have attached caudal filaments. Amongst the 115 recognized species of this genus, only Chloromyxum leydigi Mingazzini, 1890 (Pinto 1928, Gioia & Cordeiro 1996, C. ovatum and C. transversocostatum (Kuznetsova 1977) have attached filaments (Lom & Dyková 2006).…”

“…C. cyprini (AY604198) and C. legeri (AY604197) were found in the gall bladder of Hypophthalmichthys molitrix and Cyprinus carpio, respectively, from the Czech Republic (Fiala & Dyková 2004). C. auratum (AY971521) and C. trijugum (AY954689) were found in the gall bladder of Carassius auratus and Pomoxis nigromaculatus, respectively, from Oregon, USA (Hallett et al 2006). C. truttae (AJ581916) was found in the gall bladder epithelium and C. schurovi (AJ581917) in kidney tubules of Salmo salar in Scotland (Holzer et al 2004).…”

“…With respect to molecular data, there is information on the 18S rDNA gene for only 7 Chloromyxum species (Fiala & Dyková 2004, Holzer et al 2004, 2006, Hallett et al 2006). An analysis of the small subunit ribosomal DNA (SSU rDNA) in phylogenetic studies shows that the majority of myxosporea can be divided into 2 main clades: marine and freshwater clades.…”

Myxozoans on the Move: Dispersal Modes, Exotic Species and Emerging Diseases

“…In the USA, this species is a widespread invasive and continues to be introduced into the wild through escape from hatcheries and ponds, release from aquaria, and disposal of bait fish (Nico et al 2014). A survey of goldfish from a national USA pet store chain, revealed that 50 % of fish were infected with up to three species of six myxozoans, representing Sphaerospora, Myxobolus, Hoferellus, and Zschokkella (see Hallett et al 2006b). Species of the first three genera were also observed in fish sampled directly from an Arkansas goldfish farm (Karandashova 2008): Sphaerospora sp., Myxobolus diversus, Myxobolus cultus, and Hoferellus carassii.…”

“…Another species, Chloromyxum auratum, was prevalent in goldfish illegally introduced into an Oregon reservoir, and was thought to have been cointroduced with its vertebrate host since none of the local native fishes was infected. An appropriate invertebrate host must already have been present to sustain infections in the goldfish population (Hallett et al 2006b). Another carp myxozoan, Myxobolus koi, was introduced with its host Cyprinus carpio from Asia to the UK and the USA, and has caused mortalities of koi in ornamental ponds (Crawshaw and Sweeting 1986;Camus and Griffin 2010).…”