‘Who's who’ in renal sphaerosporids (Bivalvulida: Myxozoa) from common carp, Prussian carp and goldfish – molecular identification of cryptic species, blood stages and new members of Sphaerospora sensu stricto

Abstract

Myxozoans are a group of diverse, spore-forming metazoan microparasites bound to aquatic environments. Sphaerospora dykovae (previously S. renicola) causes renal sphaerosporosis and acute swim bladder inflammation (SBI) in juvenile Cyprinus carpio carpio, in central Europe. A morphologically similar species with comparably low pathogenicity, S. angulata has been described from C. c. carpio, Carassius auratus auratus and Carassius gibelio. To clarify uncertainties and ambiguities in taxon identification in these hosts we decided to re-investigate differences in spore morphology using a statistical approach, in combination with SSU and LSU rDNA sequence analyses. We found that developing spores of S. angulata and S. dykovae cannot be distinguished morphologically and designed a duplex PCR assay for the cryptic species that demonstrated S. dykovae is specific to C. c. carpio, whereas S. angulata infects C. a. auratus and C. gibelio. The molecular identification of myxozoan blood stages in common carp and goldfish, which had previously been ascribed to Sphaerospora spp. showed that approximately 75% of blood stages were from non-sphaerosporid coelozoic species infecting these cyprinids and more than 10% were from an alien species, Myxobilatus gasterostei, developing in sticklebacks. We hereby report non-selective myxozoan host invasion and multi-species infections, whose role in SBI still requires clarification.

Adaptive Radiation and Evolution Within the Myxozoa

“…This has led to erroneous results for PCR of samples with mixed myxozoan infections, which, in turn, led to misinterpretations of sphaerosporid evolutionary history. Corrected and additional molecular data have revealed Sphaerospora as separate myxosporean evolutionary lineage Eszterbauer et al 2013;Holzer et al 2013). However, there still appear to be a few cases of convergent evolution of myxosporeans with Sphaerospora myxospore morphotypes.…”

Molecular fingerprinting of the myxozoan community in common carp suffering Swim Bladder Inflammation (SBI) identifies multiple etiological agents

“…Using molecular methods, we recently demonstrated that myxozoan blood stages in asymptomatic common carp may belong to at least 7 different myxozoan species [15]. To clarify which myxozoans are present in the swim bladder of carp during clinical SBI and which are responsible for pathological changes we used PCR, DNA sequencing and in situ hybridisation (ISH) to determine parasite identity, number per species and exact location in the swim bladder and in other organs, thus identifying the etiological agents of SBI in common carp based on molecular diagnostics.…”

Ultrastructure and localisation of late-sporogonic developmental stages of Sphaerospora ranae (Myxosporea: Sphaerosporidae)

“…The round polar filament is a rare trait among myxozoans in general. In sphaerosporids it is documented in S. angulata, S. dykovae, S. galinae, S. molnari, S. ojiroveci, S. tincae Plehn, 1925and apparently S. ictaluri Hedrick, McDowell et groff, 1990(see Hamilton 1980, Lom et al 1982, Desser et al 1983, Lom et al 1985, Hedrick et al 1990, Kaup et al 1995, Dyková and Lom 1997, all of which parasitise freshwater fish and thus most probably belong to the Lineage B, as confirmed for S. angulata, S. molnari and S. dykovae (all three B1) , Eszterbauer et al 2013, Holzer et al 2013a. The H/S-shaped polar filament is known in both marine/ brackish and freshwater species, namely in S. epinepheli, S. sparidarum (both A), S. elegans, S. truttae (both B2), polysporoplasmid sphaerosporids S. sparis (B3) and S. mugilis (most probably B3) and S. ranae (B4) (Feist et al 1991, Supamattaya et al 1993, Mcgeorge et al 1994, Sitjà-Bobadilla and Alvarez-Pellitero 1995.…”

“…To avoid confusion, we would like to stress that species identinfications in these two papers changed in light of the demise of the genus Leptotheca Thélohan, 1895 (see gunter and Adlard 2010) and recent findings of Holzer et al (2013a) and Eszterbauer et al (2013). In fact, a new name S. dykovae was introduced for S. renicola Dyková et Lom, 1982 as a consequence of the transfer of mackerel parasite Sphaerospora renicola from the suppressed genus Leptotheca to Sphaerospora.…”