Myxobolus musseliusae (Myxozoa: Myxobolidae) from the gills of common carp Cyprinus carpio and revision of Myxobolus dispar recorded in China

Abstract

During a survey of myxozoan parasites of common carp Cyprinus carpio in Honghu Lake, Hubei Province, China, a parasite was collected that was identified as Myxobolus dispar based on an earlier description from China. However, the small subunit ribosomal DNA of this species shared only 90 % similarity with M. dispar, instead matching M. musseliusae with 100 % identity. To resolve this apparent taxonomic conflict, the validity of M. dispar reported from China was investigated. The species encountered here and in the earlier report from China both bear spores that are notably smaller than those of M. dispar in Europe. In the present study, a mucous envelope was adhered to the posterior of many fresh spores and was observed to expand and surround the spore. This structure has never been reported from fresh spores of M. dispar. Histology showed extravascular plasmodia in the gill filaments in close contact with the cartilaginous ray of the filament, which contrasts with the plasmodia of M. dispar which develop in the arteries of the gill filaments. Phylogenetically, the current species is distinct from M. dispar, instead forming a sister group with M. musseliusae. The data presented here allow us to conclude that the species isolated is M. musseliusae and that prior reports of M. dispar in China are unsubstantiated.

Supplemental description and molecular characterization of Myxobolus miyarii Kudo, 1919 (Myxosporea: Myxobolidae) infecting intestine of Amur catfish (Silurus asotus)

“…The reported species in the present work were highlighted in bold and species with spores of blunted anterior end underlined challenges the traditional taxonomy (Bahri 2008;Liu et al 2010Liu et al , 2014Zhang et al 2014) and suppression of Henneguya was also suggested (Kent et al 2001). In the present study, caudal appendages were firstly reported for some of spores of M.miyairii which is the ninth reported Myxobolus species with tailed spores after M. bizerti, M. mulleri, M. heterosporus, M. turpisrotundus, M. musseliusae, M. tsangwuensis, M. oralis, and M. khaliji (Bahri 2008;Liu et al 2010Liu et al , 2013Liu et al , 2014Zhang et al 2014). Interesting, two types of tailed spores (single tail or bifurcated tail) were firstly observed from most of plasmodia of M. miyairii which make it distinguished from the definition of Henneguya.…”

Myxobolus oralis sp. n. (Myxosporea: Bivalvulida) infecting the palate in the mouth of gibel carp Carassius auratus gibelio (Cypriniformes: Cyprinidae)

“…was not a valid feature for characterisation of the genus. Recently, some Myxobolus species have been reported with appendages similar to those of Henneguya species (ElMansy 2005, Bahri 2008, Liu et al 2010b, 2013a, which supports the opinion of Kent et al (2001). In the present study, we also observed 11% of the spores with caudal appendage.…”

Adaptive Radiation and Evolution Within the Myxozoa

“…Henneguya, Hennegoides, Unicauda, Dicauda, Tetrauronema, Thelohanellus, Neothelohanellus and Phlogospora). The Myxobolus morphotype and its variations are thus associated with over 1,100 species-some 50 % of myxosporean species described to date (Lom and Dyková 2006;Liu et al 2013). The success of the Myxobolus morphotype may relate to the lateral flattening of spores that enabled invasion of tissues from precursors that lived in organ cavities and then subsequently radiated to exploit a range of niches offered by different tissues.…”

“…The most common myxospore morphotype is that of Myxobolus, a genus which has diversified to more than 800 species histozoic in fish (Liu et al 2013). Many myxospore morphotypes associated with other tissue-dwelling genera appear to be modifications of this relatively simple morphotype, varying in only minor ways (e.g.…”