Metchnikovella Dogieli Sp. N. (Microsporidia: Metchnikovellida), a Parasite of Archigregarines Selenidium Sp. From Polychaetes Pygospio Elegans

Abstract

SummaryCysts and free spores of a metchnikovellid microsporidium were found in several specimens of an archigregarine Selenidium sp. isolated from polychaetes Pygospio elegans. Samples were collected at the littoral area of the Kandalaksha Bay of the White Sea in the year 2016. We examined this material with high-quality light optics in stained and live preparations. The structure of cysts and the host range suggest that this species belongs to the genus Metchnikovella Caullery et Mesnil, 1897. The length of the cysts varied from 9.5 to 34 µm (av. 23.8 µm); the width of the cysts was 4.8-9.2 µm (av. 8.2 µm). The number of cyst-bound spores varied from 7 to 18. Cyst-bound spores were oval or ovoid and arranged in two or three rows. The length of the spores was 2.2-3.0 µm (av. 2.6 µm); the width was 1.4-2.9 µm (av. 1.7 µm). Free spores were similar to cyst-bound ones in shape and size. We summarized available data on the species of the genus Metchnikovella. The analysis of these data proved that the shape and size of the examined cysts and the host range of this parasite differ from those of any known species. We named the observed organism Metchnikovella dogieli n. sp.

Evidence from the resurrected family Polyrhabdinidae Kamm, 1922 (Apicomplexa: Gregarinomorpha) supports the epimerite, an attachment organelle, as a major eugregarine innovation

“…The host name and the infection caused by microsporidia Metchnikovella incurvata and M. oviformis are available evidence from this species ( Caullery & Mesnil, 1914a ; Caullery & Mesnil, 1914b ; Caullery & Mesnil, 1919 ). We believe that we collected namely eugregarines P. pygospionis in the White Sea because they parasitized P. elegans polychaetes and were found to be infected by the microsporidium M. incurvata ( Paskerova et al, 2016 ; Rotari, Paskerova & Sokolova, 2015 ; Sokolova et al, 2013 )—in these articles, this gregarine is called Polyrhabdina sp.). Our transmission electron microscopic study of this eugregarine revealed peculiarities of the pellicle structure: the presence of loops of the internal lamina under epicytic grooves, which is not typical for eugregarines, and the absence of the internal lamina links at the epicytic crest bases, which is characteristic of some aseptate and septate eugregarines, e.g.…”

“…Our observations suggest that in co-infection of P. pygospionis and S. pygospionis in Pygospio elegans ( Paskerova et al, 2018 ; this study) each parasite species is more abundant than in monoinfections. Eugregarines, blastogregarines, and archigregarines regularly harbour metchnikovellid microsporidia ( Caullery & Mesnil, 1897a ; Caullery & Mesnil, 1897b ; Caullery & Mesnil, 1919 ; Ganapati, 1946 ; Mackinnon & Ray, 1931 ; Mikhailov et al, 2021 ; Paskerova et al, 2016 ; Paskerova et al, 2018 ; Rotari, Paskerova & Sokolova, 2015 ; Sokolova et al, 2013 ; Sokolova et al, 2014 ; Table S3 ). Further studies focused on metchnikovellids that infect gregarines co-occurring in the same spionid polychaete may shed some light on the diversification of metchnikovellids and co-evolution of gregarine hosts and their hyperparasitic microsporidia.…”

Diversity, Distribution and Development of Hyperparasitic Microsporidia in Gregarines within One Super-host

“…Metchnikovella dogieli, the second parasite of S. pygospionis, has oval, sometimes slightly bent spore sacs with one polar plug (Figure 2, G). Spore sacs are significantly larger than those of M. dobrovolskiji, measuring 9.5 -34 µ m in length and 4.8 -9.2 µ m in width [31]. The number of spores per sac varies from 7 to 18 (on average 12).…”

“…Polyrhabdina pygospionis is a host for Metchnikovella spiralis (Figure 2, C) and M. incurvata (Figure 2, D, E), while Selenidium pygospionis can harbor M. dobrovolskiji (Figure 2, F, G), and M. dogieli (Figure 2, H). We have monitored this system in the White Sea for over a decade [11][12][29][30][31][32][33][34]. In recent years, screenings have also been initiated in the Barents Sea.…”

“…In archigregarines infected with M. dogieli, the body becomes strongly shortened, thickened and uneven, cortical grooves are not defined. Their motility is clearly restricted and the cell is not able to curve the body to the full extent [31]. S. pygospionis infected with M. dobrovolskiji usually tend to maintain the form and motility even if there are many spore sacs and free spores in the host cytoplasm.…”