Light and electron microscopy of Myxobolus sciades n. sp. (Myxozoa), a parasite of the gills of the Brazilian fish Sciades herzbergii (Block, 1794) (Teleostei: Ariidae)

Abstract

A myxosporean parasite in the gill lamellae of the freshwater teleost fish, Sciades herzbergii (Ariidae) (Block, 1794), from the Poti River (Northeast of Brazil) was described by light and electron microscopy studies. Polysporic histozoic cyst-like plasmodia containing several life-cycle stages, including mature spores, were observed. The spores were pyriform and uninucleate, measuring 9.15 ± 0.39 μm (n = 50) long, 4.36 ± 0.23 μm (n = 25) wide and 2.61 ± 0.31 μm (n = 25) The genus Myxobolus (Bütschli, 1882) (family Myxobolidae) is one of the largest myxosporean groups and its members are important pathogens of freshwater and marine fish in several geographical areas (Eiras et al. 2005b, Lom & Dyková 2006. In a recent synopsis, 744 Myxobolus species have been identified parasitizing fish (Eiras et al. 2005b) and more recently, 792 named species of the same genus, including seven infecting amphibians, have been described (Lom & Dyková 2006). However, this number has been successively increasing over the years by the continuing description of new species in different countries, including Brazil (Casal et al. 2006, Martins & Onaka 2006, Eiras et al. 2007, Adriano et al. 2009a, b, Azevedo et al. 2009).Most of the Brazilian Myxobolus species have been described based on only light microscopy descriptions and diagrammatic drawings (Walliker 1969, Kent & Hoffman 1984, Molnár & Békési 1993, Gioia & Cordeiro 1996, Molnár et al. 1998, Cellere et al. 2002, Eiras et al. 2005a, 2007, Martins & Onaka 2006; even fewer have been described using light and ultrastructural observations (Casal et al. 1996, 2002, 2009, Tajdari et al. 2005 In this paper, we describe light and ultrastructural data for a new myxosporidian species found in the gill of the teleost fish, Sciades herzbergii, which was collected from a river Northeast of Brazil. MATERIALS AND METHODSA parasite found in the secondary gill lamellae of the freshwater teleost fish, S. herzbergii (Block, 1794) (family Ariidae) (Brazilian common name mandi), was studied. Ten specimens were collected from June-August of 2009 in the Poti River (05º05'S 42º48'W) near the city of Teresina [state of Piauí (PI)] northeast of Brazil. The fish were lightly anaesthetised with MS 222 (Sandoz Laboratories) and dissected. Cyst-like plasmodia with numerous mature spores located in the basal insertions of the gill lamellae were examined and measured in fresh mounts with a light microscope equipped with Nomarski differential interference contrast (DIC) optics. For transmission electron microscopy (TEM), small, parasitised fragments of the infected gills were fixed in 3% glutaraldehyde in 0.2 M sodium cacodylate buffer (pH = 7.2) at 4°C for 10 h, washed overnight at 4ºC with the same buffer and post-fixed in 2% OsO 4 buffered with the same solution for 3 h at 4ºC. The fragments were Myxobolus sciades n. sp. • Carlos Azevedo et al. 204 dehydrated in an ascending ethanol series with propylene oxide and embedded in Epon. Blocs were cut and semi-thin sections were stained with methylene bl...

Phylogeny, ultrastructure, histopathology and prevalence of Myxobolus oliveirai sp. nov., a parasite of Brycon hilarii (Characidae) in the Pantanal wetland, Brazil

“…oliveirai sp. nov. was compared with all Myxobolus species previously reported in fish of South America (Azevedo et al 2010, Eiras et al 2010) and other geographic regions (Eiras et al 2005). Among the South American species, M. oliveirai sp.…”

“…The Myxobolus Butschli, 1882, is the genus with the greatest number of species (approximately 790 valid spe- cies) (Eiras et al 2005, Lom & Dyková 2006) and many of these species are reported as pathogenic to fish (Kent et al 2001, Feist & Longshaw 2006. In South America, 30 Myxobolus species have been reported (Azevedo et al 2010, Eiras et al 2010), but none have been reported to infect fish from the genus Brycon.…”

Gill Disease Caused by Thelohanellus bifurcata Basu and Haldar, 1999 a Pathogenic Myxozoan Parasite in Cultured Indian Carp, Labeo rohita (Hamilton, 1822) in Punjab, India

“…The pathological symptoms caused by myxozoan parasites have been studied by many workers such as Chakravarty (1939), Mitchell (1977), Kalavati and Narasimhamurti (1985), Awal et al, (2001), Molnar (2002), Haldar (2002, 2004), Adriano et al, (2009), Chavda et al, (2010), Campos et al, (2011), Raissy and Ansari (2011) and Kaur et al, (2013). In aquaculture, all the three major carps namely, Labeo rohita Hamilton, Cirrhinus mrigala Hamilton and Catla catla Hamilton have been found to be infected with myxozoan parasites (Azevedo et al, 2010;Hemananda et al, 2009Hemananda et al, , 2012Manrique et al, 2012). Gill and dermal lesions due to myxozoan infection have been reported in many states of India (Chakravarty, 1939;Gupta and Khera, 1989;Padma Dorthy and Kalavati, 1992;Kalavati and Vaidehi, 1992;Mohan and Shanker, 1995;Kalavati and Nandi, 2007;Dar, 2013;Kaur et al, 2013).…”

Myxobolus saladensis sp. nov., a new species of gill parasite of Mugil liza (Osteichthyes, Mugilidae) from Samborombón Bay, Buenos Aires, Argentina

“…Members of Myxobolus Biitschli, 1882 are considered cosmopolitan, with many species cited in mullets. According to Zatti et al (2015) approximately 90 myxosporean species have been identifi ed in South America, of which 41 are from the this genus, mostly from Brazil Azevedo et al, 2010;2011;. Mullets live in shallow and brackish waters and are euryhaline, ranging from hypersaline lagoons to freshwater.…”