Revision and ecology of selected freshwater limpets (Burnupia spp.) in South Africa

Abstract

Freshwater limpets form part of the Burnupiidae family and there are 14 species belonging to the genus Burnupia in South Africa. Freshwater limpets has received little attention in modern molecular aquatic research. There are only three or four studies on the taxonomy of freshwater limpets, this shows how little information is known about these species. Molluscs and parasites interact in a variety of ways. Nematodes of molluscs are less researched than mollusc-trematode connections. Some parasites use molluscs as intermediate hosts, whereas other species conclude their life cycles in molluscs. The purpose of this study was to revise the taxonomy of South Africa's freshwater limpets and to investigate the presence and distribution of parasites in freshwater limpets, Burnupia spp. Burnupia specimens were collected from the Free State, North - West, Mpumalanga, Gauteng, and Limpopo. In total, two parasite species were collected from 77 Burnupia spp. A stereomicroscope was used to obtain photos of each of the Burnupia specimens that were collected. The photos were used to look for morphological characteristics that can be used to identify the species that were collected. A shedding method was used to induce the shedding of parasites from the Burnupia spp. The nematodes were fixed in 70% ethanol and studied with a light microscope. Photomicrographs of each nematode were taken to observe morphological characteristics that can be used to identify these parasites. For molecular analysis cytochrome c oxidase subunit 1 (cox1) and 18S were targeted. Phylogenetic analysis was done to determine the relationships between the limpet taxa. The sequences obtained in this study were analysed and compared to existing sequences on GenBank and BOLD. There were three Burnupia spp. obtained from this study, and they were identified and described. The nematodes that were collected were all female and were identified as Daubaylia burnupiae. The trematodes that were collected were identified and discovered through molecular analysis and this trematode was part of the Hypoderaeum genus. Future studies are needed to obtain more knowledge on the characteristics used to identify limpets because giving names to the species obtained in this study was problematic due to limited morphological features together with the limited number of available published sequences. Further studies are needed to provide more information on the taxonomy of the nematodes, the survival rate of the host, the transmission mode and if pollution has an effect of the reproduction behavior of parasites.