Morphological evaluation of Trichodina heterodentata Duncan, 1977 (Ciliophora: Peritricha) from tadpoles and fish

[摘要] English: Mobiline ciliophorans belonging to the family Trichodinidae Claus, 1874 are amongst the most common and widely distributed symbionts of fishes. Most of the 260 trichodinid species described from fishes are exclusively associated with fish hosts. A few are also associated with salamanders, crustaceans or coelenterates such as in the case of Trichodina pediculus Ehrenberg, 1831 that are hosted by fish or hydras. Juvenile and adult anurans also play host to some trichodinid species. Endotrichodinids such as T. xenopodos Fantham, 1924 infect the bladder of adult frogs during amplexus and feed on the debris within the bladder of the host. Ectotrichodinids are hosted on the skin and / or gills of various tadpole species worldwide. Tadpole trichodinids are typically not host specific and occur on fishes in the same water medium and are thus using tadpoles as facultative hosts. Only a few studies concentrated on the collection and / or identification of tadpole trichodinids in southern Africa.The objective of the present study was to determine if trichodinids hosted by tadpoles in southern Africa are fish trichodinids that are temporarily hosted by tadpoles or a different species that are not commonly found on fishes. Cross-transmission experiments indicated that trichodinids from naturally infested tadpoles could form a viable population on naturally uninfested fishes. This indicated that the tadpole trichodinids could be found on fishes in natural conditions. Trichodinids that were collected from various fish and tadpole species in South Africa and Botswana over the past 30 years, were examined. Morphological analysis of the examined trichodinids was undertaken by means of three known methods. These methods aided in describing all examined trichodinids as belonging to T. heterodentata Duncan, 1977. Trichodina heterodentata is globally distributed and has an apparent affinity for cichlids as fish hosts, but seems to be equally widely distributed on a variety of tadpole hosts, if both these hosts are available in the same water medium.

[发布机构] University of the Free State