Myxozoan genera: definition and notes on taxonomy, life-cycle terminology and pathogenic species

Abstract

Abstract.A list of myxozoan genera is presented in the current taxonomical scheme. These genera are defined; their type species and most important pathogens along with their hosts are listed. Simultaneously, definitions of actinospore stages representing sexual stages of the myxosporean life cycle are given; altogether, 17 actinospore collective groups with 180 types have been described. Life cycles of the two classes of the phylum Myxozoa, Malacosporea and Myxosporea, are briefly outlined with specification of the appropriate terms. Up to now, 4 malacosporean and 2,180 myxosporean species assigned to a total of 62 genera, have been established. The surviving classification of myxosporeans, based on spore morphology, is discussed in the context of the still fragmentary data resulting from SSU rDNA sequence analyses. The main task for the future is a rigorous, detailed morphological description combined with molecular techniques in establishment of new species and in revision of the existing ones. Establishment of a classification acceptable from morphological, biological and phylogenetical viewpoints is necessary.

Light and electron microscopic studies on turbot Psetta maxima infected with Enteromyxum scophthalmi: histopathology of turbot enteromyxosis

“…In the last few years, due to the phenomenal increase in fish aquaculture, concerns regarding myxosporean infections have increased significantly (Diamant et al 1994, Kent et al 2001, Lom & Dyková 2006, Palenzuela 2006, Feist 2008. Although enormous advances have been made in the last few decades in aspects of myxozoan phylogeny and taxonomy (Fiala 2006, Bartosová et al 2009), the whole life cycle of many species remains unknown.…”

Infection dynamics of two renal myxozoans in hatchery reared fry and juvenile Atlantic cod Gadus morhua L.

“…Myxozoans are a large phylum of metazoan parasites with approximately 2200 known species (Lom and Dyková, 2006), occurring predominantly in fish but with only a small proportion reported to be pathogenic. However, several species that sporulate in the renal tubules cause severe pathologies resulting in mortalities of up to 100 % of affected stocks e.g.…”

Morphological, histopathological and molecular characterization of Thelohanellus muscularis n. sp. (Cnidaria: Myxosporea) infecting head muscles of Labeo rohita from Ranjit sagar wetland, Punjab (India)

“…Myxospores are tear shaped or pyriform to broadly ellipsoidal. A single polar capsule is present, either pyriform or tear shaped [3]. Most of the species of Thelohanellus have been reported to be non pathogenic to their hosts, however, T. wuhanensis [4], T. hovorkai [5], T. nikolskii [6], T. kitauei [7], T. wangi [8], T. bifurcata [9], T. filli [10] have been shown to cause severe morbidity and mortality of infected fish [11][12][13][14].…”