Some additional data to the occurrence, morphology and validity of Myxobolus turpisrotundus Zhang, 2009 (Myxozoa: Myxosporea)

Abstract:Morphometric data from spores of ten myxosporean species were statistically analysed to explore myxosporean intraspecific variation in measurements when obtained from a sample from: (1) the same plasmodium, (2) different plasmodia from the same host and (3) different host individuals and localities. In some cases, significant differences in spore dimensions were found between samples from the same plasmodium, highlighting the difficulty of obtaining representative measurements of myxosporean spore. In addition, significant differences in spore dimensions were found when plasmodia from the same site of infection were compared, suggesting that measurements of spores should come from several different plasmodia of the sampling to increase the reliability of the morphology data. Moreover, significant differences in spore dimensions were observed for most spore dimensions when data were compared between localities. In all cases, there was clear overlap in ranges of dimensions even when means differed significantly. The present statistical analysis shows that intraspecific morphometric variation of myxosporean species commonly occurs, highlighting the importance of reporting ranges of measurements for a species, not just the mean dimensions, and taking into account all evidence when assigning or describing myxosporean species.Keywords: intraspe cific variation, Myxozoa, morphology, species differentiation, Myxobolidae Traditionally, myxosporean species have been identified principally on the basis of spore morphology, but DNA sequencing data have become important for resolving relationships and determining taxonomic affinities (Atkinson et al. 2015). Given that molecular data on most species are absent, comparison of spore morphology, especially detecting differences in morphometry, is crucial and necessary. However, criteria for what might represent intraspecific and interspecific morphometrics is undefined, making the species identification based on morphometric comparison somewhat subjective.Often, when a species is collected, the range and mean spore dimensions (usually including spore length, spore width and polar capsule dimensions) can be compared to known species and where overlap occurs there is a candidate species match. Host, geography and tissue infected are other characters that must be considered. When spore dimensions overlap, but other information suggesting distinct species is present, more sophisticated statistical analyses can be performed to determine if statistical differences occur between spore dimensions. For example, Easy et al. (2005) found evidence of two species of Myxobolus Bütschli, 1882 species in the musculature of Percopsis omiscomaycus (Walbaum) based on histology and molecular data. These species had overlapping but significantly different spore lengths, with the intermuscular Myxobolus procerus Kudo, 1934 Gilchrist, 1924 and Kudoa histolytica Pérard, 1928, Whipps and Kent (2006 found geographically distinct genetic lineages of the parasite and some statistical differen...

“…All these species have been identified in our former researches (Liu et al 2010, 2011, Huang 2014, Liu 2014 or other ongoing studies (Y.L. -unpublished data).…”

Section: Methodsmentioning

confidence: 79%

Intraspecific morphometric variation in myxosporeans

Zhai

Whipps

et al. 2016

“…To date, approximately 2,300 myxosporean species have been described based on spore morphology (Fiala et al 2015). However, due to incredible species diversity and uniformity of spores, which are used for species identification, distinguishing the morphologically similar species based on spore morphology alone has resulted in misidentification of several cryptic species in the past (Lom and Dyková 2006, Liu et al 2010b, 2011, Fiala et al 2015. In China, several morphologically similar myxosporean species infecting different tissues and organs of different hosts were misidentified as the same species (Chen and Ma 1998).…”

mentioning

confidence: 99%

Myxobolus pseudowulii sp. n. (Myxozoa: Myxosporea), a new skin parasite of yellow catfish Tachysurus fulvidraco (Richardson) and redescription of Myxobolus voremkhai (Akhmerov, 1960)

Zhang¹,

Zhai²,

Liu³

et al. 2017

Two species of Myxobolus Bütschli, 1882 were found in yellow catfish Tachysurus fulvidraco (Richardson). A species of Myxobolus infecting the gills was morphologically identified as Myxobolus voremkhai (Akhmerov, 1960) and it was characterised here with additional morphological and molecular data. The other species of Myxobolus infecting the host's skin did not conform to any known myxosporean species. It is characterised by the presence of round, black or milky white plasmodia with black spots. Myxospores are pyriform in frontal view and lemon-shaped in lateral view, measuring 12.9-16.2 μm (14.6 ± 0.7 μm) in length, 8.1-10.8 μm (9.4 ± 0.5 μm) in width, and 6.1-8.1 μm (7.0 ± 0.4 μm) in thickness. Two ampullaceous polar capsules are slightly unequal in size, larger polar capsule 7.2-9.5 μm (7.9 ± 0.4 μm) long by 3.0-3.9 μm (3.5 ± 0.2 μm) wide, smaller capsule 6.9-8.0 μm (7.4 ± 0.3 μm) long by 2.9-3.9 μm (3.4 ± 0.2 μm) wide. Polar filaments are coiled with seven to nine turns. Histologically, the plasmodia develop in the stratum spongiosum of skin dermis, resulting in epithelial cell shedding and immunological cell infiltration. Given the morphological and molecular differences between this species and other species of Myxobolus, we proposed the name of Myxobolus pseudowulii sp. n. for this parasite from the skin of yellow catfish. Interestingly, some spores of the new species possess Henneguya-like caudal appendages. Phylogenetically, M. pseudowulii sp. n. and M. voremkhai infecting yellow catfish group together in one clade with other parasites of Siluriformes, indicating that parasites clustering according to the fish host order may be an important factor affecting the evolution of species within the Myxobolus clade.

“…Among the myxosporean pathogens of allogynogenetic gibel carp, Myxobolus turpisrotundus Zhang, Wang, Li et Gong, 2010 is a distinctive species because it infects multi-organs of host and possesses an unusual seasonal pattern with prevalence and abundance of infections maximising in winter (Liu et al 2010, Zhang et al 2010 Nemeczek, 1911 are only of minor differences, which caused several misidentifications, especially when molecular taxonomy has not been widely used at that time (Chen and Ma 1998, Wu and Wang 2000. Later, Lu and Nie (2004) obtained the 18S rRNA gene sequence of M. turpisrotundus but followed the formerly reported identification instead of revision owing to the lack of comparative sequence data of M. rotundus from common bream Abramis brama (Linnaues).…”

mentioning

confidence: 99%

“…Later, Lu and Nie (2004) obtained the 18S rRNA gene sequence of M. turpisrotundus but followed the formerly reported identification instead of revision owing to the lack of comparative sequence data of M. rotundus from common bream Abramis brama (Linnaues). The ambiguity between M. turpisrotundus and M. rotundus has not been solved until molecular and morphological studies by Molnár et al (2009), Liu et al (2010 and Zhang et al (2010).…”

mentioning

confidence: 99%

Histopathological and ultrastructural studies of Myxobolus turpisrotundus from allogynogenetic gibel carp Carassius auratus gibelio in China

Guo

Zhai

et al. 2016

Abstract:During an ongoing systematic survey on species diversity of myxozoans parasitising allogynogenetic gibel carp Carassius auratus gibelio (Bloch) in China, plasmodia were detected in the fins, lip, jaw, gill chamber, gill arches, operculum and oral cavity of infected fish. Combining the morphological and molecular data, the present species was identified as Myxobolus turpisrotundus Zhang, Wang, Li et Gong, 2010. Histopathological examination revealed that despite infecting different organs, M. turpisrotundus always occurred in dermis, demonstrating its affinity to this tissue. Histopathological effect of M. turpisrotundus on the host is relatively mild except parasites in the gill arches producing compression of the adipose tissue and heavy adductor muscles deformation with lymphohistiocytic infiltrates. In addition, the plasmodia in different sites were with the same complex structure arrangement: cup-like cells with unknown derivation, a thin collagenous fibril layer, areolar connective tissue, basement membrane and host epithelial cell. Ultrastructural analysis showed that the parasite has monosporic pansporoblast and sporogenesis followed the usual pattern of most of the myxosporeans.