Tetractinomyxon stages genetically consistent withSphaerospora dicentrarchi(Myxozoa: Sphaerosporidae) found inCapitellasp. (Polychaeta: Capitellidae) suggest potential role of marine polychaetes in parasite's life cycle

Abstract

Known life cycles of myxosporean parasites have two hosts, but very few life cycles have been disclosed, especially in the marine environment. Sphaerospora dicentrarchi Sitjà-Bobadilla and Álvarez-Pellitero, 1992 is a systemic parasite from the European seabass, Dicentrarchus labrax (Linnaeus, 1758), a highly valuable commercial fish. It affects its health, leading to aquaculture production losses. During 2013 and 2014, an actinospore survey was conducted in a total of 5942 annelids collected from a fish farm in Algarve and from the Aveiro Estuary, in Portugal. A new tetractinomyxon actinospore was found in a capitellid polychaete, belonging to the genera Capitella collected at the fish farm. The tetractinomyxons were pyriform measuring 11·1 ± 0·7 µm in length and 7·2 ± 0·4 µm in width, and presented three rounded polar capsules measuring 2·4 ± 0·3 µm in diameter. The molecular analysis of the 18S rRNA gene sequences from the tetractinomyxons revealed a similarity of 100% with the DNA sequences deposited in the GenBank from S. dicentrarchi myxospores collected from the European seabass and the spotted seabass in the same fish farm and 99·9% similarity with the DNA sequence obtained from the myxospores found infecting the European seabass in the Aveiro Estuary. Therefore, the new tetractinomyxons are inferred to represent the actinospore phase of the S. dicentrarchi life cycle.

Involvement of sphaeractinomyxon in the life cycle of mugiliform-infecting Myxobolus (Cnidaria, Myxosporea) reveals high functionality of actinospore morphotype in promoting transmission

“…Sphaeractinomyxon types genetically more similar were the Sphaeractinomyxon type 2 reported in this study (MN037506) (96.6%) and the Sphaeractinomyxon type 1 of Rangel et al . (2016 a ) (KU569311) (95.8%).…”

“…(2019 c ) (MH017877) (97.2%), Sphaeractinomyxon type 9 of Rangel et al . (2016 a ) (KU569318) (96.5%) and a Myxobolus sp. reported from the gills, intestine and tail of M. cephalus from the Mediterranean Sea off Northern Israel (MF118765) (96.0%).…”

“…The majority of known life cycles involve freshwater species that use oligochaetes as invertebrate definitive hosts (see Eszterbauer et al ., 2015). In marine environments, polychaetes have been suggested to be the hosts of choice (Køie et al ., 2004, 2007, 2008; Rangel et al ., 2009, 2011, 2016 a ; Karlsbakk and Køie, 2012). Few exceptions are known to occur in estuarine waters: the triactinomyxon stages of Ortholinea auratae Rangel et al ., 2015 and Ortholinea labracis Rangel et al ., 2017, as well as the aurantiactinomyxon stage of Paramyxidium giardi (Cépède, 1906) Freeman and Kristmundsson, 2018, were reported to develop in marine oligochaetes (Rangel et al ., 2015, 2017; Rocha et al ., 2019 a ); while the tetractinomyxon stages of Ceratonova shasta Noble, 1950 and Parvicapsula minibicornis Kent et al ., 1997 were reported to use the freshwater polychaete Manayunkia occidentalis Atkinson et al ., 2020 as invertebrate host (Bartholomew et al ., 1997, 2006; Atkinson et al ., 2020).…”

Molecular data infers the involvement of a marine aurantiactinomyxon in the life cycle of the myxosporean parasite Paramyxidium giardi (Cnidaria, Myxozoa)

“…Styer et al ., 1991; Kent et al ., 1993; Lin et al ., 1999; Eszterbauer et al ., 2000, 2006, 2015; Kallert et al ., 2005; Marton and Eszterbauer, 2011; Székely et al ., 2014), with fewer providing information pertaining to the life cycles of myxosporean genera such as Ceratomyxa , Ceratonova , Chloromyxum , Ellipsomyxa , Gadimyxa , Hofferellus , Myxidium , Myxobilatus , Ortholinea , Paramyxidium , Parvicapsula , Sigmomyxa , Sphaerospora and Zschokkella (Grossheider and Körting, 1992; Benajiba and Marques, 1993; Yokoyama et al ., 1993; Bartholomew et al ., 1997, 2006; Holzer et al ., 2004, 2006; Køie et al ., 2004, 2007, 2008; Atkinson and Bartholomew, 2009; Rangel et al ., 2009, 2017; Karlsbakk and Køie, 2012). In marine environments, polychaetes appear to be the hosts of choice (Køie et al ., 2004, 2007, 2008; Rangel et al ., 2009, 2011, 2016 b ), with a few known exceptions occurring in estuarine waters, including Portuguese Rivers (Bartholomew et al ., 1997, 2006; Rangel et al ., 2015, 2017). Overall, few studies have aimed to investigate myxosporean biodiversity in invertebrate communities of this geographic region, with a total of 20 actinosporean types described from the raabeia (1 type), triactinomyxon (2 types), tetractinomyxon (2 types), sphaeractinomyxon (13 types), synactinomyxon (1 type) and unicapsulaticnomyxon (1 type) collective groups (Székely et al ., 2005; Rangel et al ., 2009, 2011, 2015, 2016 a , 2016 b , 2017; Rocha et al ., 2019 a , b ).…”

“…In marine environments, polychaetes appear to be the hosts of choice (Køie et al ., 2004, 2007, 2008; Rangel et al ., 2009, 2011, 2016 b ), with a few known exceptions occurring in estuarine waters, including Portuguese Rivers (Bartholomew et al ., 1997, 2006; Rangel et al ., 2015, 2017). Overall, few studies have aimed to investigate myxosporean biodiversity in invertebrate communities of this geographic region, with a total of 20 actinosporean types described from the raabeia (1 type), triactinomyxon (2 types), tetractinomyxon (2 types), sphaeractinomyxon (13 types), synactinomyxon (1 type) and unicapsulaticnomyxon (1 type) collective groups (Székely et al ., 2005; Rangel et al ., 2009, 2011, 2015, 2016 a , 2016 b , 2017; Rocha et al ., 2019 a , b ). Apart from the Raabeia type of Rocha et al (2019 a ) and the Synactinomyxon type of Székely et al .…”