Myxobolus species (Myxozoa), parasites of fishes in the Okavango River and Delta, Botswana, including descriptions of two new species

Abstract

Abstract. Fieldwork was conducted in 1998 and 1999 in the Okavango River and Delta and a total of 275 fishes representing 31 species were examined for the presence of myxosporean parasites. A total of seven myxosporeans of the genus Myxobolus Bütschli, 1882 were found infecting the fishes. Two new species namely Myxobolus etsatsaensis sp. n. from Barbus thamalakanensis Fowler, 1935 and M. paludinosus sp. n. from Barbus paludinosus Peters, 1852 are described. Myxobolus africanus Fomena, Bouix et Birgi, 1985, M. camerounensis Fomena, Marqués et Bouix, 1993, M. hydrocyni Kostoïngue et Toguebaye, 1994, M. nyongana (Fomena, Bouix et Birgi, 1985 and M. tilapiae Abolarin, 1974 are recorded for the first time in Botswana and descriptions of these species are provided.Myxosporean research in Africa dates back to the late 19 th century with Gurley (1893) being one of the earliest authors referring to the continent. The African continent boasts over a 100 myxosporean species from freshwater, brackish and marine fishes of which 84 infect primarily freshwater fishes (Fomena and Bouix 1997) and this number is continuously growing. When comparing the known African myxosporeans to the more than 1,300 species described worldwide, it is evident that for a huge continent with such high fish diversity, a large gap exists in the knowledge on the occurrence and distribution of these parasites.In southern Africa little research has been conducted on myxosporean parasites of fish, with only a few publications appearing largely on marine myxosporeans from South Africa such as Fantham (1919Fantham ( , 1930, Gilchrist (1924), Paperna et al. (1987) and Ali (2000). The only record ever of a freshwater myxosporean from Botswana is that of Peters (1971), commenting on Boulenger (1911) who published a brief note on an anabantid showing a mouth-brooding habit from the Okavango River. According to Peters (1971), Boulenger commented the following: "On examining a female, about 5 ins. long, I found seven or eight eggs about one line in diameter, closely packed on each side in a cavity behind the gills, entirely covered by operculum". While conducting comparative studies on the ethology of African Anabantidae, Peters (1971) examined the rounded bodies, which did look like eggs, and discovered that they were in fact mature plasmodia from a myxosporean infection. Now, 30 years later, the results of the first investigation into myxosporean parasites infecting fishes in the Okavango River and Delta are presented. Over a period of two years (1998 and 1999) a total of 275 fishes from the Okavango Delta, representing 31 species and 9 families were examined for the presence of myxosporean parasites. This paper reports on the occurrence of seven myxosporeans of the genus Myxobolus Bütschli, 1882 found infecting eight different host fish species in the Okavango River and Delta, Botswana. MATERIALS AND METHODSFieldwork was conducted in the Okavango River and Delta in Botswana during June and July in both 1998 and 1999. Fishes were collected using hand nets,...

Fish trypanosomes from the Okavango Delta, Botswana

“…Fish were collected in the panhandle region of the Okavango Delta using hand, seine, cast, and gills nets, or by rod and line (see Reed et al 2002) in June and July of 2001, and during August of 2002. In a mobile field laboratory, fish were measured, identified (Skelton 2000), and kept in aerated aquaria containing fresh river water.…”

“…During 2001 and2002, blood smears from 37 of 120 fishes belonging to 10 species captured in the Okavango Delta region of Botswana, were found to harbour trypanosomes. These trypanosomes displayed differing staining properties, were morphometrically variable, and ranged in total length from 29.5 to 80.8 µm.…”

Trichodinid ectoparasites (Ciliophora: Peritrichia) of freshwater fishes of the family Anabantidae from the Okavango River and Delta (Botswana)

“…Four papers dealing with other parasites have so far been published from the work done in the Okavango Delta; these are those by Van As and Van As (1999), Smit et al (2000), Moravec andVan As (2001), andReed et al (2002). The present paper deals with trichodinids from the fish family Anabantidae and is the first of a series on the trichodinids from fishes of the Okavango Delta.…”

A brief history of freshwater fish parasitology in southern Africa

“…She is now concentrating on marine fishes but did produce three papers on myxosporeans from Okavango fish. Reed et al (2002) described seven species of the genus Myxobolus, including two new species from a variety of fish hosts. Reed et al (2003) found two species of Henneguya, of which one was new, and a species of Myxobolus, as well as large plasmodia of Henneguya in catfish, C. gariepinus.…”