Myxidium-Immersum (Protozoa, Myxosporea) of the Cane Toad, Bufo-Marinus, in Australian Anura, With a Synopsis of the Genus in Amphibians

Abstract

Myxidium immersum (Lutz, 1889), a gall-bladder protozoan parasite from South American Anura, is described for the first time in some Australian Anura. The cane toad, Bufo marinus, one of its natural hosts in South America, was introduced into Australia in 1935, and this led to the infection of native Australian frogs including: Hylidae, 12 species of Litoria; Myobatrachidae, four species of Limnodynastes, one each of Mixophyes, Ranidella and Uperoleia. Scanning electron microscope observations on the spore are reported. A synopsis of the Myxidium species in amphibians is presented. In explaining the present distribution of M. immersum in Australia, it is suggested that the life cycle of Myxidium species in amphibians involves an intermediate host which may become infected by swallowing trophozoites and spores; the tadpole may become infected by feeding on the intermediate host.

Comparative morphology of the gallbladder and biliary tract in vertebrates: Variation in structure, homology in function and gallstones

“…Myxidium lesminteri was observed in the gallbladders of three southern African anurans (Delvinquier et al, 1992). Myxidium immersum is a gallbladder parasite of the African cane toad (Delvinquier, 1986;Delvinquier and Freeland, 1988).…”

Giant toads Bufo marinus in Australia and Venezuela have antibodies against 'ranaviruses'

“…and Rhabdias spherocephala have been identified as causing pathological changes in B. marinus or diseases in other amphibians, fish or mammals (Hird et al 1981, Speare 1990, Hau et al 1992, Subasinghe 1992, Twiddy & Reilly 1994, Prasad & Rao 1995. Infectious agents which have been identified in/with B. marinus within Australia include species of protozoa, helminths and fungi (Delvinquier 1986, Delvinquier & Freeland 1988a, b, Speare 1990, Speare et al 1994. A notable pathogen is Mucor amphibiorum .…”

Myxidium lesminteri n. sp. (Myxosporea: Myxidiidae) from the gall-bladder of three southern African Anura

“…This conclusion was disputed by McAllister & Upton (1987), who found 48.1% Ambystoma texanum from Dallas County, Texas, were infected, and stated that "there is little host specificity in amphibians for the myxosporean". Similarly, Delvinquier (1986) found M. immersum in 19 native species of Australian anurans and the introduced Bufo marinus. There was no indication of a preferred host.…”

“…It differs from all other species in amphibians by having a smooth shell. Myxidium immersum and M. serotinum both have shells with transverse striations (Lutz, 1889;Cordero, 1919;Kudo & Sprague, 1940;Clark & Shoemaker, 1973;Delvinquier, 1986), whereas M. haldari has a shell with longitudinal striations (Sarkar, 1982). Other species of Myxidium in southern Africa have been described from salt-water fishes (Fantham, 1930;Dubina & Isakov, 1976).…”

“…However, three species have been described from the gallbladders of amphibians (Delvinquier, 1986). During a survey of southern African Anura, we discovered a fourth species from amphibians.…”