The genus Coitocaecum Nicoll, 1915 is part of the most speciose digenean family, the Opecoelidae Ozaki, 1925, which is found globally in both freshwater and marine fishes. Fifteen opecoelid species have been reported from marine fishes in South Africa, yet only one species of Coitocaecum has been described from this region: Coitocaecum capense Bray, 1987. During an explorative study of the digeneans of the endemic, intertidal fish Clinus superciliosus (Linnaeus) from the Saldanha Bay area, Cape Town harbour, Hermanus, the Tsitsikamma section of the Garden Route National Park and Chintsa East in South Africa, a total of three distinct species of Coitocaecum were identified based on morphological and molecular (28S rDNA, ITS1-5.8S-ITS2 rDNA and COI mtDNA) data: the previously mentioned C. capense, Coitocaecum brayi sp. n. and a third, unnamed species. We provide the first molecular characterisation of species of Coitocaecum from South Africa, accompanied by detailed morphological descriptions. This study illustrates the importance of an integrated taxonomic approach, especially when studying species with similar morphology. These findings further emphasise the lack of information on the true diversity and molecular data for trematodes of marine fishes in South Africa, creating a great capacity for future explorative taxonomic studies and highlighting the use of intertidal areas for conducting such research.

Institute of Ecology Nature Research Centre Vilnius Lithuania

Water Research Group Unit for Environmental Sciences and Management Potchefstroom Campus North West University Potchefstroom South Africa

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Aken'Ova T.O., Cribb T.H. 1996: Two species of Coitocaecum Nicoll, 1915 (Digenea: Opecoelidae) from Moreton Bay, Queensland, Australia. Syst. Parasitol. 33: 217‒224. DOI

Andres M.J., Pulis E.E., Overstreet R.M. 2014: New genus of opecoelid trematode from Pristipomoides aquilonaris (Perciformes: Lutjanidae) and its phylogenetic affinity within the family Opecoelidae. Folia Parasitol. 61: 223‒230. DOI

Barnett L.J., Miller T.L., Crib T.H. 2014: A review of the currently recognized opecoelid cercariae, including the identification and emergence ecology of Cercaria capricornia XII (Digenea: Opecoelidae) from Nassarius olivaceus (Gastropoda: Nassariidae) in Central Queensland, Australia. Parasitol. Int. 63: 670‒682. PubMed DOI

Bowles J., Blair D., McManus D.P. 1995: A molecular phylogeny of the human schistosomes. Mol. Phylogenet. Evol. 4: 103‒109. PubMed DOI

Bray R.A. 1987: Some helminth parasites of marine fishes of South Africa: family Opecoelidae (Digenea). J. Nat. Hist. 21: 1049‒1075. DOI

Bray R.A., Cribb T.H., Littlewood T.J., Waeschenbach A. 2016: The molecular phylogeny of the digenean family Opecoelidae Ozaki, 1925 and the value of morphological characters, with the erection of a new subfamily. Folia Parasitol. 63: 013. DOI

Bray R.A., Cutmore S.C., Cribb T.H. 2022: A paradigm for the recognition of cryptic trematode species in tropical Indo-west Pacific fishes: the problematic genus Preptetos (Trematoda: Lepocreadiidae). Int. J. Parasitol. 52: 169‒203. PubMed DOI

Cribb T.H., Anderson G.R., Adlard R.D., Bray R.A. 1998: A DNA-based demonstration of a three-host lifecycle for the Bivesiculidae (Platyhelminthes: Digenea). Int. J. Parasitol. 28: 1791‒1795. PubMed DOI

Cribb T.H. 2005. Family Opecoelidae Ozaki, 1925. In: A. Jones, R.A. Bray and D.I. Gibson (Eds), Keys to the Trematoda, Volume 2. CAB International and The Natural History Museum, Wallingford, pp. 443‒532. DOI

Edgar R.C. 2004: MUSCLE: multiple sequence alignment with high accuracy and high throughout. Nucleic Acids Res. 32: 1792‒1797. PubMed DOI

Froese R., Pauly D. (Eds) 2023: FishBase. World Wide Web electronic publication, www.fishbase.org.

Galazzo D.E., Dayanandan S., Marcogliese D.J., McLauglin J.D. 2002: Molecular systematics of some North American species of Diplostomum (Digenea) based on rDNA-sequence data and comparisons with European congeners. Can. J. Zool. 80: 2207‒2217. DOI

Jousson O., Bartoli P., Pawlowski J. 1999: Molecular identification of developmental stages in Opecoelidae (Digenea). Int. J. Parasitol. 29: 1853‒1858. PubMed DOI

Koehler A.V., Springer Y.P., Keeney D.B., Poulin R. 2011: Intra- and inerclonal phenotypic and genetic variability of the trematode Maritrema novaezealandensis. Biol. J. Linn. Soc. 103: 106‒116. DOI

Kudlai O., Cutmore S.C., Cribb T.H. 2015: Morphological and molecular data for three species of the Microphallidae (Trematoda: Digenea) in Australia, including the first descriptions of the cercariae of Maritrema brevisacciferum Shimazu et Pearson, 1991 and Microphallus minutus Johnston, 1948. Folia Parasitol. 62: 053. DOI

Littlewood D.T.J., Curini-Galletti M., Herniou E.A. 2000: The interrelationships of Proseriata (Platyhelminthes: Seriata) tested with molecules and morphology. Mol. Phylogenet. Evol. 16: 449‒466. PubMed DOI

Manter H.W. 1954: Some digenetic trematodes from fishes of New Zealand. Trans. R. Soc. N. Z. 82: 475‒568.

Martin S.B., Cutmore S.C., Cribb T.H. 2018: Revision of Podocotyloides Yamaguti, 1934 (Digenea: Opecoelidae), resurrection of Pedunculacetabulum Yamaguti, 1934 and the naming of a cryptic opecoelid species. Syst. Parasitol. 95: 1‒31. PubMed DOI

Martin S.B., Cutmore S.C., Cribb T.H. 2020b: The Pseudoplagioporinae, a new subfamily in the Opecoelidae Ozaki, 1925 (Trematoda) for a small clade parasitizing mainly lethrinid fishes, with three new species. J. Zool. Syst. Evol. Res. 58: 79‒113. DOI

Martin S.B., Downie A.J., Cribb T.H. 2020a: A new subfamily for a clade of opecoelids (Trematoda: Digenea) exploiting marine fishes as second-intermediate hosts, with the first report of opecoelid metacercariae from an elasmobranch. Zool. J. Linn. Soc. 188: 455-472. DOI

Martin S.B., Huston D.C., Cutmore S.C., Cribb T.H. 2019: A new classification for deep-sea opecoelid trematodes based on the phylogenetic position of some unusual taxa from shallow-water, herbivorous fishes off south-west Australia. Zool. J. Linn. Soc. 186: 385‒413. DOI

Morgan J.A.T., Blair D. 1995: Nuclear rDNA ITS sequence variation in the trematode genus Echinostoma: an aid to establishing relationships within the 37-collar-spine group. Parasitology 111: 609‒615. PubMed DOI

Moszczynska A., Locke S.A., McLaughlin D., Marcogliese D.J., Crease T.J. 2009: Development of primers for the mitochondrial cytochrome c oxidase I gene in digenetic trematodes (Platyhelminthes) illustrates the challenge of barcoding parasitic helminths. Mol. Ecol. Resour. 9: 75‒82. PubMed DOI

Pleijel F., Jondelius U., Norlinder E., Nygren A., Oxelman B., Schander C., Sundberg P., Thollesson M. 2008: Phylogenies without roots? A plea for the use of vouchers in molecular phylogenetic studies. Mol. Phylogenet. Evol. 48: 369‒371. PubMed DOI

Posada D. 2008: jModelTest: Phylogenetic Model Averaging. Mol. Biol. Evol. 25: 1253‒1256. PubMed DOI

Rambaut A., Suchard M.A., Xie D., Drummond A.J. 2012: FigTree v1.4.3. Available from: http://tree.bio.ed.ac.uk/software.figtree.

Rohner C.A., Cribb T.H. 2013: Opecoelidae (Digenea) in northern Great Barrier Reef goatfishes (Perciformes: Mullidae). Syst. Parasitol. 84: 237‒253. PubMed DOI

Shedko M.B., Sokolov S.G., Atopkin D.M. 2015: The first record of Dimerosaccus oncorhynchi (Trematoda: Opecoelidae) in fishes from rivers of Primorsky Territory, Russia, with a discussion on its taxonomic position using morphological and molecular data. Parazitologiia 49: 171-189. PubMed

Snyder S.D., Tkach V.V. 2001: Phylogenetic and biogeographical relationships among some Holarctic frog lung flukes (Digenea: Haematoloechidae). J. Parasitol. 87: 1433‒1440. PubMed DOI

Sokolov S.G., Shchenkov S.V., Gordeev I.I. 2019: Records of opecoeline species Pseudopecoelus cf. vulgaris and Anomalotrema koiae Gibson, Bray, 1984 (Trematoda, Opecoelidae, Opecoelinae) from fish of the North Pacific, with notes on the phylogeny of the family Opecoelidae. J. Helminthol. 93: 475-485. PubMed DOI

Tkach V.V., Littlewood D.T.J., Olson P.D., Kinsella J.M., Swiderski Z. 2003: Molecular phylogenetic analysis of the Microphalloidea Ward, 1901 (Trematoda: Digenea). Syst. Parasitol. 56: 1‒15. PubMed DOI

Tkach V., Pawlowski J., Mariaux J. 2000: Phylogenetic analysis of the suborder Plagiorchiata (Platyhelminthes, Digenea) based on partial lsrDNA sequences. Int. J. Parasitol. 30: 83‒93. PubMed DOI

Tkach V.V., Snyder S.D., Swiderski Z. 2001: On the phylogenetic relationship of some members of Macroderoididae and Ochetosomatidae (Digenea, Plagiorchioidea). Acta Parasitol. 46: 267‒275.

Van Steenkiste N., Locke S.A., Castelin M., Marcogliese D.J., Abbott C.L. 2015: New primers for DNA barcoding of digeneans and cestodes (Platyhelminthes). Mol. Ecol. Resour. 15: 945‒952. PubMed DOI

Von der Heyden S., Bowie R.C.K., Prochazka K., Bloomers P., Crane N.L., Bernardi G. 2011: Phylogeographic patterns and cryptic speciation across oceanographic barriers in South African intertidal fishes. J. Evol. Biol. 24: 2505‒2519. PubMed DOI

Morphological description and molecular characterisation of Opegaster mezcal sp. n. (Trematoda: Opecoelidae) from the Mexican Tropical Pacific