Xenopus laevis as UberXL for nematodes

Abstract

The effect of invasive species on local parasite dynamics is often overlooked. The African Clawed Frog Xenopus
laevis (Daudin, 1802) (Anura: Pipidae) is a global invader, with established populations on four continents and is a domestic exotic in southern Africa. Despite a century of parasitological surveys, the current study reports seven previously unrecorded nematode species parasitising X. laevis across South Africa. These are adult Capillaria sp. and Falcaustra sp. from the intestine, third stage larvae of Contracaecum sp. encysted in the body cavity, third stage larvae of Paraquimperia sp. and Tanqua sp. from the intestine and two different species of second stage nematode larvae from the lungs and kidneys, respectively. Morphological descriptions,  photomicrographs and molecular data of the 18S and 28S rRNA and COI genes are provided to aid future investigations. We propose that these nematodes could well be using X. laevis as a definitive, paratenic and intermediate host, probably involving native fish, piscivorous birds, semi-aquatic reptiles and invertebrates in their life cycles. All recovered nematodes are recorded for the first time herein in association with X. laevis, except for the genus Contracaecum, members of which have previously been recorded from invasive X. laevis from California and Chile. The current study illustrates that X. laevis is an important parasite reservoir in its native range, with implications for its role in the invasive range. The fact that none of these nematodes could be identified to species level underscores the importance of providing morphological descriptions and molecular data when reporting on parasitological surveys, especially those of known invasive species.

Keywords: African clawed frog, Capillaria, Contracaecum, Falcaustra, Paraquimperia; parasite reservoir, Tanqua