A new species of Cichlidogyrus Paperna, 1960 (Platyhelminthes: Monogenea: Dactylogyridae) infecting tilapias in Lake Kariba (Zimbabwe), with a discussion on its phylogenetic position

Abstract

Monogeneans dominate the external parasite fauna of bony fish. During recent years, examination of more populations and species of Cichlidogyrus Paperna, 1960 has led to the (re)description of several species. Cichlidogyrus halli (Price & Kirk, 1967) Price, 1968, for example, has been redescribed several times in the past and has been proposed to encompass many (pseudo)cryptic species. In Lake Kariba (Zimbabwe), specimens of a species of Cichlidogyrus were found that morphologically resemble C. halli. These specimens were found on the gills of native Oreochromis cf. mortimeri and Coptodon rendalli (Boulenger, 1897), and introduced Nile tilapia Oreochromis niloticus (Linnaeus, 1758). A detailed study of the morphology of these specimens, including morphometrics, and a thorough comparison with specimens of C. halli is presented. Part of the COI gene and 18S-ITS1 fragment were sequenced and analysed to provide insight into the phylogenetic placement of these specimens within the Cichlidogyrus–Scutogyrus monophylum. We found that C. halli and the new specimens sp. nov. are sister clades within the same monophyletic clade, and that clear morphological and morphometric differences are present in the dorsal bar of the haptor (auricles almost twice as long as in C. halli) and the male copulatory organ (wider penis stylet, longer accessory piece with a more elongated and less pronounced terminal triangular cap, narrower heel, as compared with C. halli). Based on these results, the new specimens are described as a new species: C. chloeae sp. nov. The role of introduced Nile tilapia as a potential reservoir for native parasites raises concern for potential spillbacks and stresses the need for further monitoring of monogeneans on native and introduced tilapias.

http://zoobank.org/urn:lsid:zoobank.org:pub:DAF7DD13-6A31-4271-970B-A03DEEDD3938

Key words:

• Cichlidogyrus
• Dactylogyridae
• Lake Kariba
• Monogenea
• Oreochromis
• tilapia
• Zimbabwe

Acknowledgements

We appreciate the help of the people involved in the fieldwork and sampling procedure, especially Maxwell Barson (University of Zimbabwe/University of Botswana) and Shandré van der Merwe (Royal Museum for Central Africa/KU Leuven, Belgium). Furthermore, we would like to thank Christopher Laumer (EMBL-European Bioinformatics Institute, UK) and Gontran Sonet (Royal Belgian Institute of Natural Sciences, Belgium) for providing us with the extraction protocol and R scripts, respectively. Finally, we would like to thank Ria Vanderspikken (Hasselt University, Belgium) and Natascha Steffanie (Hasselt University, Belgium) for their technical support in the laboratory, and Timo Pajunen (Finnish Museum of Natural History, University of Helsinki, Finland) and Christophe Allard (Royal Museum for Central Africa, Belgium) for curatorial services.

Competing interests

The authors report there are no competing interests to declare.

Supplementary material

Supplementary material for this article can be accessed here: https://doi.org/10.1080/14772000.2022.2143594.

Associate Editor: Dr Peter D. Olson

Notes

1 The term ‘tilapia’ will be used in the present study to refer to a paraphyletic group of cichlids consisting of several haplotilapiine tribes, including commercially important genera, such as Oreochromis Günther, 1889, Tilapia Smith, 1840, Coptodon Gervais, 1853, and Sarotherodon Rüppell, 1852 (Dunz & Schliewen, 2013; Trewavas, 1982).

Additional information

Funding

This work was supported by the Special Research Fund of Hasselt University (Grants BOF17NI02 and BOF20TT06); the Research Foundation—Flanders (FWO-Vlaanderen; Grant N 1513419). The research leading to results presented in this publication was carried out with infrastructure funded by EMBRC Belgium–FWO project GOH3817N.